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1
Wang, Ping. "Diffusion of small organic molecules in fluoroelastomers /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1995.
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Thesis (Ph.D.)--Tufts University, 1995.Adviser: Nak-Ho Sung. Submitted to the Dept. of Chemical Engineering. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Velardo, Amalia. "Small organic molecules for next generation electronics." Doctoral thesis, Universita degli studi di Salerno, 2016. http://hdl.handle.net/10556/2215.
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2014 - 2015In this PhD thesis attention has been focused on the theoretical design of organic small molecules for next generation electronics. The task of this thesis has concerned with the theoretical analysis of the operational performances of small dyes in photovoltaic solar cells, both in bulkheterojunction and dye sensitized solar cells; with particular emphasis on the theoretical analysis of the rates of the elementary electron transfer processes. A full quantum mechanics procedure for computing the rates of elementary electron transfer processes has been developed. The procedure starts from the Fermi Golden Rule (FGR) expression of the rate of electronic transitions and makes use of a rigorous evaluation of the Franck-Condon weighted density of states, performed by Kubo’s generating function approach. The analysis of electron transfer rates has revealed to be a very powerful tool for investigating structure-property relationships for the employment of small organic molecules in photovoltaic solar cells. The methodology has been applied to a class of small organic molecules, which show different power energy conversion efficiencies. The different efficiencies of the dyes have been attributed to very different rates of photoinduced electron transfer, the first step of energy conversion process in any type of photovoltaic solar cell. The last part of this thesis has been devoted to a very important task for next generation electronics: the rational design of new N-rich fused-ring heteroaromatics small organic molecules for n-type charge transport in thin layers. The substitution of CH units with nitrogen atoms is particularly appealing because, it offers the possibility of tuning the electron donor/acceptor character of the molecule. [edited by author]
XIV n.s.
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Kindness, A. "Infrared intensities of some small molecules." Thesis, University of Aberdeen, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277293.
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The work described in this thesis had two main aims: (1) to develop a method for the determination of 13C/12C ratios by measuring the areas of individual rotational lines in gas phase spectra; (2) to measure the absolute infrared intensities of the CH stretching bands in the gas phase of various small molecules, especially partially deuterated species containing only one CH bond. Both projects involved the use of a Fourier Transform Infrared spectrometer, (FT-IR). In part one, infrared spectra of CO, HCN, CH4 and CO2 were investigated to identify the species most suitable for isotopic abundance determination. Of these, carbon dioxide exhibits the largest shift (ca. 60 cm-1) and is the easiest to prepare and handle in a vacuum system. Procedures for handling organic and carbonate samples have been developed. The precision, on about 2 mg carbon, was satisfactory with a rsd = 1.2 % at the natural abundance level and a limit of detection of 0.026 atom % 13C above the natural abundance level of 1.136 atom % 13C. Results obtained by this method were found to be in good agreement with those obtained by Mass spectrometry. In part two, the absolute intensities of the CH stretching bands in the spectra of C2H6, C2D5G, C3H8, CD3CD2CD2H, (CD3)2CDH, (CH3)3CH, (CD3)3CH, (CH3)3CD, C6D11H and CHD2X (where X = C1, I, NH2, OH and O-CHD2) were measured using the pressure broadening technique. Where data was obtained for both deuterated and partially deuterated species, the extent of validity of the additivity of intensity per CH bond was explored. Individual CH band intensitites in the various compounds are compared with results from previous studies, where available. Chemical variations are discussed in terms of the electro-optical parameters approach of Gussoni et al.
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Neri, Tommaso. "Novel organic semiconducting small molecules for X-ray detection." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14809/.
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L’elettronica organica ha trovato negli anni recenti diverse applicazioni, anche in dispositivi di uso quotidiano, come ad esempio gli schermi OLED (Organic Light Emitting Diode). I semiconduttori organici possono essere depositati con tecniche a basso costo, anche su scala industriale, e su grandi aree, fattore, quest’ultimo, che li rende particolarmente adatti alla fabbricazione di sensori di radiazioni ionizzanti. Il lavoro presentato riguarda la realizzazione di transistor organici a film sottile e la loro caratterizzazione, come transistor e come sensori di raggi X. In particolare, l’obiettivo di questo progetto sperimentale è il confronto delle sensibilità di due tipi di dispositivi fabbricati da soluzioni delle molecole diF-TES-ADT (5,11-bis(triethylsilylethynyl)anthradithiophene) e diF-TEG-ADT (5,11-bis(triethylgermylethynyl)anthradithiophene), appartenenti alla classe degli eteroaceni sostituiti. Nella prima molecola sono presenti due gruppi funzionali identici in cui è contenuto un atomo di silicio, mentre nell'altra essi contengono un atomo di germanio, caratterizzato da un numero atomico più alto. In questo lavoro viene dimostrato che il numero atomico più alto, grazie al maggiore coefficiente di assorbimento per la radiazione X, comporta una sensibilità più alta per il sensore di razioni ionizzanti, come confermato dai risultati ottenuti.
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Ferguson, A. M. "Spectroscopic and theoretical studies of small molecules." Thesis, Robert Gordon University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374240.
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Raspanti, Fabio. "Organic small molecules semiconductors as direct X-ray detectors." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15451/.
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Organic small molecules semiconductors are promising in the field of direct ionizing radiation detection.
Unlike their inorganic counterpart, these molecules are easy to work with, since they are flexible, soluble and can be deposited on electronic devices with very simple processes, such as drop-casting and spin-casting. Moreover, these materials have good detection properties and very low working voltage.
To this day, organic semiconductors have mainly been used in indirect radiation detection, employed both in scintillator and as photodetectors. However, direct detection of ionizing radiation is a far more effective method, since it is performed within a single material and a single conversion, directly from photons to electrical signal; furthermore, it provides a higher signal-to-noise ratio and a faster response time.
In this experimental work, I fabricated four direct detectors based on transistors; two different organic solutions were drop-casted onto the transistors, creating a conduction channel between source and drain electrodes.
Both these solutions had chlorobenzene as a solvent, with DiF-TES-ADT and DiF-TEG-ADT as solutes, respectively, in a 0.5% concentration.
The purpose of this thesis is dual. Firstly, I want to study how the detectors’ sensitivity is influenced by semiconductor molecules with different Z-number; secondly, I want to test a new drop-casting method (SAC method) and compare it to results previously obtained with traditional deposition methods.
The results are very promising, with very high values of sensitivity obtained with low voltages.
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Sultana, Mahmooda. "Microfluidic systems for continuous crystallization of small organic molecules." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59879.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
This thesis presents one of the first demonstrations of continuous crystallization in microfluidic devices, and illustrates their use for various applications related to crystallization of small organic molecules. Crystallization is an important process in a number of industries, including specialty chemicals, food, cosmetics, nutraceuticals and, most importantly, pharmaceuticals. Most small molecule pharmaceuticals are isolated in crystalline form, and more than ninety percent of all pharmaceutical products are formulated in particulate, mainly crystalline form. However, crystallization is not a completely understood process. The sensitivity of the process to synthesis conditions gives rise to serious reproducibility issues. The traditional batch crystallizers suffer from non-uniform process conditions across the reactor, and chaotic, poorly controlled mixing of the reagents, often resulting in polydisperse crystal size distribution and impure polymorphs. This makes it difficult to obtain reliable information on the process kinetics that can be used for scale-up, as well as to study the fundamentals of the process. Microfluidic systems offer a unique toolset for crystallization because of well-defined laminar flow profiles, enhanced heat and mass transfer, better control over the contact mode of the reagents, and optical access for in situ characterization. The better control over the synthesis conditions gives rise to the potential for controlling the crystal size, as well as the polymorphic form. In addition, low consumption of reagents makes it an attractive research tool for expensive pharmaceutical compounds. Some of the advantages of microfluidics have been demonstrated for crystallization in micro-batches, but so far not in continuous devices. Continuous crystallization is difficult to achieve in microchannels as uncontrolled nucleation, crystal growth, agglomeration and sedimentation of crystals easily clog the small channels. The interaction of crystals with channel walls may also contribute to channel plugging in these devices. This thesis has developed microfluidic devices for continuous crystallization of small organic molecules for the first time. We have decoupled nucleation and growth, the two key steps of crystallization, using reaction engineering principles, and have developed two separate continuous devices, one for each of these two processes. We have used seeded crystallization and reactor design to achieve controlled growth, as well as to suppress secondary nucleation, agglomeration and sedimentation of crystals. In addition, we have eliminated any significant interaction of crystals with channel walls by controlling the properties of channel surfaces. We have also integrated microscopy and spectroscopy tools with the device for in-situ characterization of crystal size and polymorphic form. We have illustrated the use of these devices to extract growth kinetics data for crystals of various shapes, including high aspect ratio systems such as that with acicular or plate-like habits. The reproducibility and control in our devices have allowed us to elucidate the growth mechanism and fundamentals of the growth process for difficult crystal systems. In addition, we have demonstrated that continuous microfluidic devices offer a unique advantage over the current state-of-the art technology to measure the size, size distribution and growth kinetics of high aspect ratio crystal systems more accurately. Moreover, we have demonstrated the use of microfluidic devices for understanding crystal habit modification in the presence of impurities. We take advantage of the high spatiotemporal resolution of microfluidic devices to study the evolution of crystal habit over time, and to obtain information on the kinetics of habit modification in the presence of different impurities. We have developed an understanding of the habit modification mechanism for alpha glycine in the presence of alpha amino acids. Such information may not only provide insights into impurity-crystal interactions, but also serve as a powerful tool for the design of impurities that can be deliberately added to improve the crystallization process. Furthermore, we have designed and developed a second microfluidic device for continuous supercritical crystallization for the first time. Using supercritical fluid as an antisolvent, we have demonstrated continuous spontaneous nucleation of acetaminophen. We have shown the ability to produce micron-sized crystals, which may be useful for increasing the bioavailability of drugs with lower solubility, as well as for inhalable and highly potent drugs with stringent size requirements. The developed platform can also be used as a high-throughput device for safely screening crystallization conditions in the supercritical domain. We have demonstrated such use by screening the effects of pressure and various solvents on the habit, size and polymorphic form of acetaminophen crystals.
by Mahmooda Sultana.
Ph.D.
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Zhao, Qingjun. "The electrocatalytic oxidation of small organic molecules on platinum." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057092834.
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Bye, Jordan. "Interaction between macromolecules, inorganic salts and small organic molecules." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7731/.
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Solutes are present within aqueous systems in almost every area of research. The term solute can include salts, small organic molecules, proteins and any other chemical that can be dissolved. Understanding how solutes influence the properties of each other and medium they are dissolved in is of paramount importance if a system is to be fully understood, but the extent to which solutes perturb their medium is often overlooked. The aim of this research project was to use analytical techniques such as differential scanning calorimetry, pressure perturbation calorimetry and terahertz spectroscopy to better understand the mechanism by which water and solutes influence protein stability. Experimental results suggest that Hofmeister ions influence protein stability at higher salt concentrations by modulating the free energy required to hydrate the newly exposed core of the protein. Destabilising ions reduce the free energy required to hydrate the protein core and stabilising ions increase the free energy. At low salt concentrations salts influence protein stability to a small degree by interacting electrostatically with proteins. Pressure perturbation calorimetry studies suggested that Hofmeister ions are able to influence water dynamics at elevated temperatures through their electric field. These findings support the hypothesis that ions are able to stabilise proteins by competing for water with the unfolding protein through an electrostatic interaction. Coherent synchrotron radiation in the terahertz region of the electromagnetic spectrum was able to detect an extended hydration layer around bovine serum albumin. These findings supported other terahertz spectroscopy experiments that also detected extended hydration layers around proteins and suggests that water around protein molecules is more complex than a single layer of water molecules.
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Boschi, Francesca <1980>. "New routes to enantioenriched substances through small organic molecules." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1458/1/Boschi_Francesca_tesi.pdf.
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In this thesis we will disclose the results obtained from the diastereoisomeric salt formation (n salt, p salt and p1,n1 salt) between non-racemic trans-chrysanthemic acid (trans-ChA) and pure enantiomers of threo-2-dimethylamino-1-phenyl-1,3-propanediol (DMPP). The occurrence of p1,n1 salt formation can have profound effects on enantiomer separation of scalemic (non-racemic) mixtures. This phenomenon when accompanied by substrate self-association impedes the complete recovery of the major enantiomer through formation of an inescapable racemate cage.
A synthetic sequence for the asymmetric synthesis of bicyclo[3.2.0]heptanones and bicyclo[3.2.0]hept-3-en-6-ones through a cycloaddition strategy is reported. The fundamental step is a [2+2]-cycloaddition of an enantiopure amide derived from the reaction between a set of acids and an oxazolidinone as the chiral auxiliary. The inter- and intramolecular cycloaddition of in situ-generated keteniminium salts gives bicycles with a good enantioselection.
A key intermediate of Iloprost, a chemically stable and biologically active mimic of prostacyclin PGI2 is synthesized following a ‘green approach’. An example of simple optical resolution of this racemic intermediate involving the diastereoisomeric salt formation is described.
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Boschi, Francesca <1980>. "New routes to enantioenriched substances through small organic molecules." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1458/.
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In this thesis we will disclose the results obtained from the diastereoisomeric salt formation (n salt, p salt and p1,n1 salt) between non-racemic trans-chrysanthemic acid (trans-ChA) and pure enantiomers of threo-2-dimethylamino-1-phenyl-1,3-propanediol (DMPP). The occurrence of p1,n1 salt formation can have profound effects on enantiomer separation of scalemic (non-racemic) mixtures. This phenomenon when accompanied by substrate self-association impedes the complete recovery of the major enantiomer through formation of an inescapable racemate cage.
A synthetic sequence for the asymmetric synthesis of bicyclo[3.2.0]heptanones and bicyclo[3.2.0]hept-3-en-6-ones through a cycloaddition strategy is reported. The fundamental step is a [2+2]-cycloaddition of an enantiopure amide derived from the reaction between a set of acids and an oxazolidinone as the chiral auxiliary. The inter- and intramolecular cycloaddition of in situ-generated keteniminium salts gives bicycles with a good enantioselection.
A key intermediate of Iloprost, a chemically stable and biologically active mimic of prostacyclin PGI2 is synthesized following a ‘green approach’. An example of simple optical resolution of this racemic intermediate involving the diastereoisomeric salt formation is described.
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Stückenschneider, Kai [Verfasser]. "Molecular Modeling of Adsorptive Interactions between Small Organic Molecules and Zeolites / Kai Stückenschneider." München : Verlag Dr. Hut, 2014. http://d-nb.info/1055863079/34.
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Lozano-Casal, Patricia. "Structural and computational studies of small organic and biological molecules." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/1954.
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Over the last three decades high-pressure X-ray diffraction techniques have been widely utilised to perform structural studies in many areas of research. For example, physicists make use of these experimental techniques to investigate metals, conductor and semi-conductor compounds among others, whereas geochemists apply them to study the conditions deep within the Earth’s interior. Furthermore, pressure studies have reached an important status in chemistry, biology and planetary science, and have proved to be a new notable tool to study the structure of a variety of small molecule compounds, from inorganic (e.g. rock salt) to organic (e.g. urea) and biological molecules (e.g. amino acids). The main reason for this is the necessity to obtain a better understanding of different processes which take place at extreme conditions of pressure, such as the existence of life in the deep ocean (e.g. extremophiles) or the finding of amino acids, such as cysteine, in space. Small molecules, such as glycine and glutathione, may play important roles in these biological processes and therefore a good knowledge of their structural features could be essential to explain how they happen. The work described here focuses on one of the principal features of intermolecular bonding in small organic and biological molecules, namely the hydrogen bond. Although the hydrogen bond has been studied for almost a century, this important directional intermolecular interaction is still one of the most highly investigated topics in chemistry and biology due to the many aspects of its nature which are still unknown or not well understood. The hydrogen bond is directly involved with the crucial biochemical processes of amino acids, peptides, proteins and even DNA and RNA and therefore, in short, it is essential for life. Its importance goes beyond biomolecules and organic molecules, since the hydrogen bond is also present in inorganic compounds, such as clusters containing different types of ligands and metals, e.g. manganese and iron, and consequently it is implicated in many catalytic pathways. In this work, we have combined experimental and computational techniques to investigate the effect of pressure on the crystal structures of amino acids and small organic molecules, and in particular on the crystal packing of cyclopropylamine, α-glycine, L-α-aspartic acid and L-α-glutamine. The experimental study of these structures was aimed to determine the principal structural changes as a function of pressure. The computational study was carried out to investigate the energetics of the crystal structures: i.e., the sublimation, lattice and proton transfer energies, as well as the energies of the individual hydrogen bonds, in order to relate the structural changes observed by experiment. A new computational method was initially tested on the simplest naturally occurring amino acid, α-glycine, which had been previously studied experimentally at high pressure by our research group. Experimental results support the existence of a new polymorph of cyclopropylamine (Phase II), which was found at 1.2 GPa. This new molecular structure crystallises in the orthorhombic space group Pbca, with 8 molecules in the unit cell and one in the asymmetric unit. The molecular packing is formed by zig-zag chains of molecules linked via a short N-H…N hydrogen bond, with unusually only one of the hydrogen atoms of the NH2 group of the cyclopropylamine molecule involved in the hydrogen bonding network. A computational study was applied to the two polymorphs of cyclopropylamine (Phase I and Phase II), in order to investigate the energetics of these systems. It was found that the energies of the hydrogen bonds present in the Phase I and Phase II crystal structures of cyclopropylamine have very similar energies, falling in the range of 1 to 4 kcal mol-1 (6 to 16 kJ mol-1). Experimental results on amino acids showed that the effect of pressure (from 0 to approximately 6 GPa) did not cause significant changes in the crystal structures of L-α-aspartic acid and L-α-glutamine, other than a decrease in the lengths of the various hydrogen bonds and intermolecular contacts. Additionally, ab initio calculations carried out on α-glycine, L-α-aspartic acid and L-α-glutamine indicated that the hydrogen bonds present in the crystal structure of amino acids exhibit very different energies, falling over a much wider range of 1 to 30 kcal mol-1 (∼4 to 120 kJ mol-1), compared to that found for small organic molecules. This finding does not agree with what was expected according to previous hydrogen bonding classifications, and we attribute this to the zwitterionic nature of the amino acid molecules which is present in the solid state. Finally, it was found that the energies of the hydrogen bonds found in the amino acids investigated correlates with the experimental compressibility studies, so that the hydrogen bond exhibiting the lowest energy is also the weakest, and most easily compressed.
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Gantenbein, Markus [Verfasser]. "Small Organic Molecules: Building Blocks of Functional Materials / Markus Gantenbein." München : Verlag Dr. Hut, 2015. http://d-nb.info/1074063554/34.
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Rattana, Acharawan. "The interfacial chemistry of small organic molecules on aluminium substrates." Thesis, University of Surrey, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288839.
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Prasetya, Nor Basid Adiwibawa. "Synthesis of polymers and small molecules with organic photovoltaic applications." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8458/.
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This thesis describes the synthesis and characterisation of polymers and small molecules with organic photovoltaic applications. The first chapter of this thesis provides an introduction to organic semiconductors and the working principle of organic photovoltaics. An overview of active materials used in BHJ, as well as examples of some of their performance, is also provided. The second chapter describes the synthesis and characterisation of subphthalocyanine (SubPc) derivatives as active materials for OPV applications. Modifications on the periphery and axial substituents of the SubPcs have been carried out to tailor their physical, optical and electrochemical properties. Among the synthesised SubPcs derivatives, three molecules have been employed as acceptor materials for solution processed BHJ solar cells. The highest performance was achieved when using PTB7 as donor material with a PCE of 3.51%. The third chapter describes the synthesis and characterisation of push-pull small-molecule materials based on the thiophene motif with the objective to explore their application as p-type semiconductors in BHJ devices. The electrochemical studies indicate that the extension of the donor conjugation can reduce the fundamental gap by rising the IP energy level, while the strong electron-accepting moiety can reduce the fundamental gap by lowering the EA energy level. Five molecules have been tested as donor materials for solution processed BHJ solar cells, reporting a PCE of 1.66% as the highest performing donor when blended with PC61BM as the acceptor. The fourth chapter describes the synthesis and characterisation of two naphthalimide-based small molecules bridged with different donor moieties (fluorene and phenothiazine derivatives). Acetylene units were introduced as the bridge between the donor and the acceptor moieties to extend the conjugation and ensure the planarity of the synthesised molecules. Based on their energy levels, the two molecules can be employed as potential donor and acceptor materials for solution processed BHJ devices and will be tested in the future. Finally, the fifth chapter describes the syntheses of polythiophenes and benzothiadiazole-based copolymers with the objective to explore their application as donor materials in BHJ devices. Two polythiophene polymers were successfully synthesised and characterised. One of the polythiophene polymers was comprised of a glycol side chain, namely P3(TEG)T, showing good solubility, offering a wide range selection of solvents for BHJ devices fabrication. Another polythiophene was synthesised via Huisgen cycloaddition reaction between ethynyl end-capped P3HT polymer and a naphthalene glycol derivative containing an azide end group. The polymer was successfully isolated with a narrow dispersity (Ð). The studies indicate that additional naphthalene glycol moiety does not change the thermal, optical and electrochemical properties of the polymer. Two polymers containing BT moiety were also synthesised and characterised. All the polymers have a low energy gap with IP and EA values above those of fullerene derivatives. As a result, the polymers could potentially act as an efficient p-type semiconductor in BHJ solar cells. In this work, the polymer P3(TEG)T has been tested its performance in BHJ solar cell devices, displaying very poor performance. The low efficiency was associated with low charge-mobility indicated from low JSC value.
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Wright, Helen. "Fused ring conjugated polymers and small molecules for organic-semiconductors." Thesis, University of Manchester, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542784.
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Fused ring structures such as cyclopentadithiophenes (CPDT), fluorenes and dithienopyrroles have been shown to have low band gaps and extended conjugation lengths. Both of these properties make them interesting materials for organic semiconductor applications. It has been shown that increasing the planarity of building blocks, and in turn the polymer or molecule they are contained within, can improve charge transport by increasing π-π stacking. While the homo-polymers of dithienopyrrole, and alkene bridged CPDT and fluorene have low band gaps, it is possible to further reduce them by forming co-polymers, either by combination with an acceptor unit or by increasing the planarity of the polymer. Three families of small molecules and corresponding co-polymers were therefore synthesised using three main building blocks - alkene bridged CPDT, alkylidene fluorene and dithienopyrrole - combined with a series of co-monomers. In the cases of CPDT and dithienopyrrole two different alkyl chains were used with the aim of influencing solubility and solid-state packing. The optical and electrochemical properties were studied and trends determined. In addition physical and thermal properties were studied and for several of the small molecules, crystal structures and theoretical structures were also evaluated to probe intermolecular interactions in the solid state.During the synthesis of one alkylidene fluorene small molecule an unexpected impurity was isolated in which the bridging alkene of the fluorene had rearranged. Possible reasons for the formation were investigated and the properties of the compound studied.Several small molecules and one co-polymer were incorporated into preliminary OFET devices, although performance was limited by poor film formation. Film forming studies were also undertaken on the co-polymer.
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Schünemann, Christoph. "Organic Small Molecules: Correlation between Molecular Structure, Thin Film Growth, and Solar Cell Performance." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-105169.
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Das wesentliche Ziel dieser Doktorarbeit ist es, die Zusammenhänge zwischen der Struktur von kleinen organischen Molekülen, deren Anordnung in der Dünnschicht und der Effizienz organischer Solarzellen zu beleuchten. Die Kombination der komplementären Methoden spektroskopischer Ellipsometrie (VASE) und Röntgenstreuung, vor allem der unter streifendem Einfall (GIXRD), hat sich als sehr effiient für die Strukturuntersuchungen organischer Dünnschichten erwiesen. Zusammen geben sie einen detailreichen Einblick in die intermolekulare Anordnung, die Kristallinität, die molekulare Orientierung, die optischen Konstanten n und k und die Phasenseparation von organischen Schichten. Zusätzlich wird die Topografie der organischen Dünnschicht mit Rasterkraftmikroskopie untersucht. Der erste Fokus liegt auf der Analyse des Dünnschichtwachstums von Zink-Phthalocyanin (ZnPc) Einzelschichten. Für alle untersuchten Schichtdicken (5, 10, 25, 50 nm) und Substrattemperaturen (Tsub=30°C, 60°C, 90°C) zeigt ZnPc ein kristallines Schichtwachstum mit aufrecht stehenden ZnPc Molekülen. Um effiziente organische Solarzellen herzustellen, werden Donor- und Akzeptormoleküle üblicherweise koverdampft. Bei der Mischung von Donor- und Akzeptormolekülen bildet sich eine gewisse Phasenseparation aus, deren Form wesentlich für die Ladungsträgerextraktion entlang der Perkolationpfade ist. Der Ursprung dieser Phasenseparation wird innerhalb dieser Arbeit experimentell für ZnPc:C60 Absorber-Mischschichten untersucht. Um die Ausprägung der Phasenseparation zu variieren, werden verschiedene Tsub (30°C, 100°C, 140°C) und Mischverhältnisse (6:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:6) bei der Koverdampfung von ZnPc und C60 angewendet. GIXRD Messungen zeigen, dass hier der bevorzugte Kristallisationsprozess von C60 Molekülen die treibende Kraft für eine effiziente Phasenseparation ist. Solarzellen, die ZnPc:C60 Mischschichten mit verbesserter Phasenseparation enthalten (Tsub=140°C, 1:1), zeigen eine verbesserte Ladungsträgerextraktion und somit eine höhere Effizienz von 3,0% im Vergleich zu 2,5% für die entsprechende Referenzsolarzelle (Tsub=30°C, 1:1). Im zweiten Teil der Arbeit wird der Einfluss der Molekülorientierung auf die Dünnschichtabsorption beispielhaft an ZnPc und Diindenoperylen (DIP) untersucht. DIP und ZnPc Moleküle, die auf schwach wechselwirkenden Substraten wie Glas, SiO2, amorphen organischen Transportschichten oder C60 aufgedampft sind, zeigen eine eher stehende Orientierung innerhalb der Dünnschicht in Bezug zur Substratoberfläche. Im Gegensatz dazu führt die Abscheidung auf stark wechselwirkenden Substraten, wie z.B. einer Gold- oder Silberschicht oder 0.5 nm bis 2 nm dünnen PTCDA (3,4,9,10-Perylentetracarbonsäuredianhydrid) Templatschichten laut GIXRD und VASE Messungen dazu, dass sich die ZnPc und DIP Moleküle eher flach liegend orientieren. Dies führt zu einer wesentlich besseren Dünnschichtabsorption da das molekulare Übergangsdipolmoment jeweils innerhalb der Ebene des ZnPc und des DIP Moleküls liegt. Ein Einbetten von Gold- oder Silberzwischenschichten in organischen Solarzellen führt leider zu keinen klaren Abhängigkeiten, da die verbesserte Absorption durch die flach liegenden Moleküle von Mikrokavitäts- und plasmonischen Effekten überlagert wird. Ebenso wenig führte das Einfügen einer PTCDA-Zwischenschicht in organischen Solarzellen zum Erfolg, da hier Transportbarrieren den Effekt der verbesserten Absorption überlagern. Das letzte Kapitel konzentriert sich auf den Einfluss der Molekülstruktur auf das Dünnschichtwachstum am Beispiel von DIP und dessen Derivaten Ph4-DIP und P4-Ph4-DIP, Isoviolanthron und Bis-nFl-NTCDI (N,N-Bis(fluorene-2-yl)-naphthalenetetra-carboxylic Diimid) Derivaten. GIXRD Messungen belegen deutlich, dass die sterischen Behinderungen, hervorgerufen durch die Phenylringe (für Ph4-DIP und P4-Ph4-DIP) und Seitenketten (für Bis-nFl-NTCDI), ein amorphes Schichtwachstum induzieren. Im Vergleich sind die Dünnschichten von DIP und Bis-HFl-NTCDI kristallin. Bezüglich der Molekülorientierung und folglich der Absorption von DIP und dessen Derivaten kann ein starker Einfluss des Schichtwachstums beobachtet werden. In Solarzellen verhindert die Präsenz der Phenylringe eine effiziente Phasenseparation der Mischschichten aus (P4-)Ph4-DIP:C60, was zu einer verschlechterten Ladungsträgerextraktion und damit zu einem reduzierten Füllfaktor (FF) von 52% im Vergleich zu dem entsprechender DIP:C60 Solarzellen mit FF=62% führt Die Untersuchungen an der Bis-nFl-NTICDI Serie zeigen ein ähnliches Ergebnis: Auch hier zeichnen sich die amorphen Schichten aus Bis-nFl-NTCDI Molekülen mit Seitenketten durch schlechtere Transporteigenschaften aus als nanokristalline Bis-HFl-NTCDI SchichtenThe aim of this thesis is to demonstrate correlations between the molecular structure of small organic molecules, their arrangement in thin films, and the solar cell performance. For structure analysis of the organic thin films, the combination of variable angle spectroscopic ellipsometry (VASE) and grazing incidence X-ray diffraction (GIXRD) as complementary methods turned out to be a powerful combination. Using both methods, it is possible to obtain information about the crystallinity, crystallite size, intermolecular arrangement, mean molecular orientation, optical constants n and k, and phase separation within thin films. In addition, the topography of thin films is analyzed by atomic force microscopy. First, the thin film morphology of pristine zinc-phthalocyanine (ZnPc) films deposited at different substrate temperatures (Tsub=30°C, 60°C, 90°C) and for varying film thicknesses (5, 10, 25, 50 nm) is investigated. The ZnPc films grow highly crystalline with an upright standing molecular orientation with respect to the substrate surface for all investigated Tsub and all film thicknesses. In effcient organic solar cells, donor and acceptor molecules are commonly co-deposited to form a blend absorber film. This is usually accompanied by a certain phase separation between donor and acceptor molecules leads to a formation of percolation paths necessary to extract electrons and holes towards the electrodes. For ZnPc:C60 blends the origin of this phase separation process is analyzed by investigating different degrees of phase separation induced by film deposition at different Tsub (30°C, 100°C, 140°C) and for different blend ratios (6:1, ... , 1:6 (vol%)). GIXRD measurements indicate that the preferred crystallization of C60 is the driving force for good phase separation. Solar cells with improved phase separation of ZnPc:C60 blends (Tsub=140°C, 1:1) reveal a better charge carrier extraction and thus enhanced effciencies of 3.0% in comparison to 2.5% for the reference device (Tsub=30°C, 1:1). In the second part, the impact of molecular orientation within the absorber thin films on light harvesting is examined for pristine ZnPc and diindenoperylene (DIP) films. For film deposition on weakly interacting substrates like glass, SiO2, amorphous organic transport films, or C60, the orientation of DIP and ZnPc molecules is found to be upright standing. In contrast, GIXRD and VASE measurements show that films deposited onto strongly interacting substrates like Au and Ag, as well as on thin PTCDA templating layers lead to nearly flat-lying ZnPc and DIP molecules. Since the molecular transition dipole moment is oriented in the plane of the DIP and ZnPc molecules, the light absorption in films with flat-lying molecules is strongly improved. Unfortunately, an implementation of Au or Ag sublayers in organic solar cells does not result in reliable dependencies since the enhanced absorption by an improved molecular orientation is superimposed by different effects like microcavity and plasmonic effects. The implementation of PTCDA interlayers leads to transport barriers making the solar cell data interpretation difficult. In the last part, the influence of molecular structure on thin film growth is studied for DIP and its derivatives Ph4-DIP and P4-Ph4-DIP, isoviolanthrone, and Bis-nFl-NTCDI derivatives. GIXRD measurements reveal that steric hindrance is induced by the addition of side chains (for Bis-nFl-NTCDI) and phenyl rings (for Ph4-DIP and P4-Ph4-DIP) (N,N-Bis(fluorene-2-yl)-naphthalenetetra-carboxylic diimide) leading to an amorphous thin film growth. In contrast, DIP films and Bis-HFl-NTCDI films are found to be crystalline. The mean molecular orientation and hence the absorption is strongly affected by the different growth modes of DIP and its derivatives. In OSC, the presence of the phenyl rings prevents an effcient phase separation for (P4-)Ph4-DIP:C60 blends which causes diminished charge extraction in comparison to the crystalline DIP:C60 blends. For the Bis-nFl-NTCDI series, the transport properties are significantly worse in the amorphous films composed of Bis-nFl-NTCDI derivatives with alkyl chains in comparison to the nanocrystalline films made of the bare Bis-HFl-NTCDI
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Higgins, Jessica Anne. "Organouranium complexes for the insertion and reduction of small molecules." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/53503/.
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This thesis explores the behaviour of U(III) and U(IV) organometallic complexes towards small molecules, with respect to both their reductive activity and insertion chemistry. A range of mixed-sandwich U(IV) organyl complexes of the form U(η-C8H6{1,4-SiiPr3}2)(η-C5Me5)(R) (= U(COTTIPS2Cp*(R), where R = CH3, CH2Ph, CH2TMS, CH{TMS}2) have been synthesised and the products of their reactions with CO2, CO, and H2 (κ2-carboxylates, η2-acyls, and a monomeric terminal hydride) have been characterised – all of which are formed under mild conditions (< 1 atm of gas, sub-ambient temperature). The hydride also inserts CO2 to yield a formate, U(COTTIPS2)Cp*(κ2-O2CH), which is the first example of its kind, and inserts CO to form cis-enediolate, {U(COTTIPS2)Cp*}2(μ-κ1:κ1-OCH=CHO). A rare primary amido, U(COTTIPS2)Cp*(NH2), and its CO2 insertion product, U(COTTIPS2)Cp*(κ2-O2CNH2), have also been characterised. The latter is the first crystallographically characterised U(IV) primary carbamate. Deprotonation of the parent amido yield an anionic U(IV) terminal primary imido, [U(COTTIPS2)Cp*(NH)][K(18-crown-6)]. U(III) and U(IV) complexes containing a dianionic diamidoamine ligand, [N{SiMe3}(CH2CH2N{SiMe3})2]2- (= N'N'2) have been synthesised. It has been found that the migration of a SiMe3 group along the ligand backbone occurs spontaneously when bound to uranium. Reduction of the U(IV) compound U(N'N'2)Cp*Cl with KC8 yields either the U(III) product, U(N'N'2)Cp*, or bridging arene products, {U(N'N'2)}2(μ-η6:η6-C6H5R) (where R = H, Me), depending on the reaction stoichiometry. Further reactivity of these diamidoamine complexes with small molecules is also discussed.
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Hu, Jin. "The binding and activation of small molecules by rhenium thiolato-complexes." Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306071.
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Charmant, Jonathan Paul Henry. "Reactivity of the #mu#3-benzyne ligand towards small organic molecules." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238905.
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Singh, Harjit. "The synthesis and evaluation of small organic molecules as cholecystokinin antagonists." Thesis, Aston University, 2002. http://publications.aston.ac.uk/11007/.
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Cholecystokinin (CCK) is a peptide hormone, present in the alimentary and the CNS. It is the most abundant peptide in the brain. CCK has been implicated in a number of disorders. The link between CCK and anxiety was the basis for this research. A comprehensive discussion on the many types of CCK receptor antagonists is included. For the drug discovery process, a number of synthetic approaches have been investigated and alternative chemical approaches developed. 1,4-Benzodiazepine analogues were prepared, with substitutents In the 1,2 & 3- position of the benzodiazepine scaffold varied, and substituted 3-anilino benzodiazepines exhibited the greatest in vitro activity towards the CCKA receptor subtype. Through extensive screening, pyrazolinone-ureido derivatives were identified, optimised, SAR studied and re-screened. A comprehensive in vivo study on the most active analogue is included, which has a number of common structural features with L-36S, 260 including activity. Pyrazolinone-amide derivatives, bearing the tryptophan moiety were equally active. A number of existing and novel furan- 2(SH)-one building blocks were prepared, from which a selected mini-library of 4- amino-substituted furan-2(SH)-ones were prepared and evaluated. All synthesised compounds were evaluated in a CCK radiolabelled binding assay (CCKA & CCKB), with compounds demonstrating receptor selectivity and lead structures being discovered. The work in this thesis has identified a number of highly active prime structures, from which further investigations are essential in providing more in vitro & in vivo data and the need to prepare more analogues.
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Xiang, Yuanhui. "SILYL KETENES AS BUILDING BLOCKS FOR SMALL MOLECULES AND POLYMERS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1561113802285453.
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Liu, Xinli. "Molecular design of new small molecules and polymers: synthesis, characterization and application in organic solar cells." HKBU Institutional Repository, 2013. https://repository.hkbu.edu.hk/etd_oa/16.
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The molecular design, synthesis, spectroscopic and photophysical characterization of a new series of organic small molecules and transition metal-containing polymers incorporating different n-conjugated chromophores are discussed. The applications of some of these compounds in bulk heterojunction (BHJ) organic solar cells are also outlined. Chapter 1 contains a brief overview on the background of organic solar cells, their structures and performance in solution-processed organic BHJ devices. Chapter 2 presents the synthetic methodology and characterization of a series of new dipyrrin-based materials and their application in organic solar cells. In this section, four metal-based metallopolymers for organic solar cells have been designed, synthesized and two of them have been fabricated for BHJ organic solar cells. Through the alternation of different metal ions and boron element in the same dipyrrin framework, a series of dipyrrin-based metal complexes and BODIPY-containing compounds have been synthesized. Electrochemical analysis and DFT calculations proved that M4 with BODIPY-based structure is more efficient in optimizing the HOMO-LUMO energy level which further increases the Voc value. A full account of the preparation, characterization, photophysical and thermal properties of a new series of benzo[1,2-b:4,5-b']dithiophene (BDT), cyclopenta[2,1-6:3,4-6']dithiophene (CPT) and triphenylamine (TPA) centered small molecules are presented in chapters 3, 4 and 5, respectively. Different acceptor-donor-acceptor (A-D-A) based materials were prepared and employed in organic solar cells in order enhance the power conversion efficiency (PCE) of the devices. Some of the materials have been found to show higher PCEs of up to 3.91%. Given the excellent solution-processability as well as performance advantage, this work provides us a feasible strategy to develop low-cost and high PCE materials in solar cell applications, which would help small molecular organic solar cells to reach a level of practical applications. In chapter 6, four low-bandgap Pt-containing polymers were synthesized and characterized by a variety of techniques. Among them, the largest λonset of 699 nm in solution and λonset of 736 nm in the thin film of P6 were observed and the corresponding energy gap Eg was estimated to be 1.77 eV and 1.68 eV, respectively. After evaluating these oxidation and reduction potentials, P6 also showed the smallest band gap of 1.65 eV with the corresponding HOMO and LUMO energy levels of -5.17 eV and -3.52 eV, respectively. Also, the molecular weights of these polymers were examined by the GPC method. The highest Mn of 24.0 kDa and Mw of 50.4 kDa with the PDI of 2.10 were observed in P8. Chapter 7 and 8 present the concluding remarks and the experimental details of the work described in Chapters 2-6.
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Cabau, Parra Lydia. "Design and Synthesis of Small Molecules for Organic and Grätzel Solar Cells." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/320183.
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El creixement de la població i dels nous països emergents fa que el consum energètic es dispari. Tota la població depèn d’aquest consum i com a conseqüència es depèn de les reserves de combustibles fòssils disponibles.
Una de les fonts d’energia no esgotable i que proveu a la terra d’una gran quantitat d’energia es el Sol. Aquesta Energia ja està sent explotada amb la utilització de panells solars basades en silici. No obstant degut al seu alt cost de fabricació no poden competir amb les fonts d’energia ja existents. Per tant, noves investigacions en alternatives han estat àmpliament estudiades.
Unes de les alternatives que han estat àmpliament estudiades durant aquests anys han estat les cel·les sensitivitzades amb colorant (DSSC) i les cel·les orgàniques (OPV). Les bases i el funcionament d’aquests dos tipus de dispositius es mostren en el capítol 1.
El principal estudi d’aquesta tesis es centra en el disseny i la síntesis de nous colorants per aquest tipus de dispositius. Aquests colorants tenen un paper molt important en aquests dispositius i moltes vegades la seva eficiència deriva de l’estructura d’aquests colorants degut a les reaccions que es produeixen en els dispositius.
En el Capítol 3 i 4 es presenta el disseny de dos tipus de colorants pel que fa a les cel·les sensitivitzades amb colorant (DSSC). En el capítol 3 es tracta de noves molècules orgàniques amb estructura D-π-A àmpliament estudiades com a alternativa als complexes de ruteni. En el capítol 4 les molècules sintetitzades també per DSSC són una família de porfirines, les quals són les que actualment estan mostrant més eficiència.
Per una altra banda en el capítol 5 s’ha sintetitzat també una porfirina però en aquest cas per estudiar la seva aplicabilitat en les cel·les solars orgàniques (OPV).El Crecimiento de la población I de nuevos países emergentes hace que el consume energético se dispare. Toda la población depende de este consume I como consecuencia se depende de las reservas de combustibles fósiles disponibles. Una de las Fuentes de energía no agotable y que suministra a la tierra de una gran cantidad de energía es el Sol. Esta energía ya está siendo explotada con la utilización de paneles solares basados en Silicio. Sin embargo, debido a su elevado coste de fabricación no pueden competir con fuentes de energía ya existentes. Por lo tanto, nuevas investigaciones en alternativas han estado estudiadas. Una de las alternativas que han sido más estudiadas son las Celdas sensitibizadas con colorante (DSSC) i las Celdas Orgánicas (OPV). Las bases y su funcionamiento se muestran en el capítulo 1. El principal estudio de esta tesis se centra en el diseño y la síntesis de nuevos colorantes para estos tipos de dispositivos. Estos colorantes tienen un papel muy importante en estos dispositivos y muchas veces su eficiencia deriva de la estructura del colorante debido a reacciones que se producen en el dispositivo. En el Capítulo 3 y 4 se presenta el diseño de dos tipos de colorantes para las celdas sensitibizadas con colorante. En el Capítulo 3 se muestran moléculas orgánicas con estructura D--A que han sido ampliamente estudiadas como alternativa a los complejos de rutenio. En el capítulo 4 una familia de porfirinas ha sido sintetizada debido a los prometedores resultados mostrados siendo en la actualidad las moléculas que dan más eficiencia. En el Capítulo 5 en cambio se ha sintetizado una porfirina, pero en este caso para estudiar su aplicabilidad en las celdas orgánicas (OPV)
The population is growing and the consumption of energy is dramatically increasing. All the population depends on this energy and are using fossil fuels available. One of this renewable source that gives to the earth a huge amount of energy is the sun. This source is exploited nowadays with photovoltaic devices based in silicon. However due to their high cost of production is not an alternative comparing with the existent sources. For this reason scientists of the entire world are working hard in the development of alternative devices in order to reduce the cost, decrease the contamination and increase the efficiencies among others. Some of alternatives that have been widely studied during the last years have been the Dye Sensitized Solar Cells (DSSC) and Organic Solar Cells (OPV). Basic principles of these devices are showed in Chapter 1. Principally the study of this thesis was focused in the design and synthesis of new sensitizers for these devices. These sensitizers play an important role in these devices and many times their structure depends on the efficiency of the device. In Chapter 3 and 4 the design and synthesis of two kinds of sensitizers and their applicability in DSSC is showed. In chapter 3 the sensitizers are organic dyes with a structure of D-π-A widely studied as alternative to the ruthenium complexes. In chapter 4 another family of sensitizers have been synthesized and also their applicability in DSSC has been studied. In this chapter the molecules are a family of porphyrins that are the molecules that nowadays are showing the most efficiency. On the other hand in Chapter 5 a new porphyrin has been synthesized but in this case to study their applicability in Organic solar Cells (OPV)
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Lee, Jaeyoung. "Electro-oxidation of small organic molecules kinetic instabilities and spatiotemporal pattern formation /." [S.l.] : [s.n.], 2001. http://www.diss.fu-berlin.de/2001/210/index.html.
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Guérin, Frédéric. "Pyridine diamide complexes of early transition metals, activation of small organic molecules." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ27151.pdf.
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Hulme, Ashley Thomas. "Combined experimental and computational studies of the polymorphism of small organic molecules." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1446010/.
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Polymorphism is the ability of a molecule to adopt more than one crystalline form and the control of polymorphism is of importance to the fine chemical industry. Complimentary computational crystal structure prediction and experimental crystallisation techniques have been used to investigate the polymorphism of four organic molecules, none of which were previously known to be polymorphic. For each molecule computational crystal structure prediction produced possible crystal structures, which could correspond to new polymorphs. Manual crystallisation techniques were employed in three instances, and an automated crystallisation platform was used in the fourth, to discover new polymorphs. The crystal structures of all new polymorphs and solvates were fully determined, where possible, by single crystal X-ray diffraction for comparison to the predicted structures. The 5-fluorouracil crystallisation screen produced one new polymorph which corresponded to a low energy predicted structure. For 5-fluorocytosine, where no anhydrous forms had previously been determined, two new polymorphs were discovered, one of which was predicted by the computational results. The study on 3-azabicyclo 3.3.1 nonane-2,4-dione aimed to find a new hydrogen bond dimer-based polymorph inspired by the results of earlier prediction studies. The crystallisation screen produced one new polymorph which was structurally related to the previously reported chain-based structure, along with a high temperature plastic phase. Four polymorphs of 4-hydroxycoumarin were discovered, of which two were fully characterised by single crystal X-ray diffraction and two were identified by powder X-ray diffraction. Many of the newly discovered solvates of these molecules had their hydrogen bonding rationalised in terms of the hydrogen bonded motifs found in the predicted structures of the parent molecule. The viability of computationally predicting monohydrate structures was investigated, using 5-azauracil monohydrate as a test system. This proved a success, with the known crystal structure found by the computational method to be energetically competitive with the other hypothetical structures.
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Hutchison, Ian Blackwood. "High pressure as a tool for polymorph screening in small organic molecules." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28491.
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Application of high pressure is a well-known tool used to induce. Presented in this thesis are the studies of three small organic molecules under high pressure,investigating the importance of particle size, the choice of pressure-transmitting medium (PTM) and the solvent from which the material is recrystallised on the high-pressure behaviour of the material. Chapters 3 describes the characterisation of a metastable polymorph of glycolide,formed at high pressure and recovered to ambient conditions. Chapter 4 describes a neutron diffraction study of glycolide under high pressure, characterising the behaviour of each of the two known forms as well as seeking to characterise a third polymorph which had been observed during earlier work. Chapter 5 presents a neutron diffraction study of acrylamide under high pressure inthree different pressure-transmitting media – a 1:1 (v/v) mixture of pentane and isopentane,a 4:1 (v/v) mixture of methanol and ethanol, and iso-propyl alcohol (IPA).A different high pressure phase was identified in each of the three media, with the crystal structures of those in the pentanes and methanol/ethanol environments being fully solved. Chapter 6 describes a study of caprolactam under high pressure, through a combination of single crystal X-ray diffraction and powder neutron diffraction. In this study, it was observed that a caprolactam sample recrystallised from ethylacetate underwent a polymorph transition to one high pressure phase, while a sample recrystallised from alcohol (either ethanol or 1-butanol) underwent a polymorph transition to a different high pressure form despite the fact that both samples were in the same polymorphic form at the beginning of the experiment. The high pressure form observed from the sample recrystallised from ethanol (or 1-butanol) was fully structurally solved. Recent progress made by the group beyond the scope of this PhD have permitted unit cell parameters to be fitted to the neutron diffraction data, although associated discussion of this form is limited due to time constraints.
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Geng, Ting. "Excited-state dynamics of small organic molecules studied by time-resolved photoelectron spectroscopy." Doctoral thesis, Stockholms universitet, Fysikum, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-140482.
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Ultra-violet and visible light induced processes in small organic molecules play very important roles in many fields, e.g., environmental sciences, biology, material development, chemistry, astrophysics and many others. Thus it is of great importance to better understand the mechanisms behind these processes. To achieve this, a bottom-up approach is most effective, where the photo-induced dynamics occurring in the simplest organic molecule (ethylene) are used as a starting point. Simple substituents and functional groups are added in a controlled manner to ethylene, and changes in the dynamics are investigated as a function of these modifications. In this manner, the dynamics occurring in more complex systems can be explored from a known base. In this thesis, the excited state dynamics of small organic molecules are studied by a combination of time-resolved photoelectron spectroscopy and various computational methods in order to determine the basic rules necessary to help understand and predict the dynamics of photo-induced processes. The dynamics occurring in ethylene involve a double bond torsion on the ππ* excited state, followed by the decay to the ground state coupled with pyramidalization and hydrogen migration. Several different routes of chemical modification are used as the basis to probe these dynamics as the molecular complexity is increased. (i) When ethylene is modified by the addition of an alkoxyl group (-OCnH2n+1), a new bond cleavage reaction is observed on the πσ* state. When modified by a cyano (-CN) group, a significant change in the carbon atom involved in pyramidalization is observed. (ii) When ethylene used to build up small cyclic polyenes, it is observed that the motifs of the ethylene dynamics persist, expressed as ring puckering and ring opening. (iii) In small heteroaromatic systems, i.e., an aromatic ring containing an ethylene-like sub-structure and one or two non-carbon atoms, the type of heteroatom (N: pyrrole, pyrazole O: furan) gives rise to different bond cleavage and ring puckering channels. Furthermore, adding an aldehyde group (-C=O) onto furan, as a way to lengthen the delocalised ring electron system, opens up additional reaction channels via a nπ* state. The results presented here are used to build up a more complete picture of the dynamics that occur in small molecular systems after they are excited by a visible or UV photon, and are used as a basis to motivate further investigations.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.
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Beaumont, Nicola L. "Investigating new materials and understanding the ambipolar qualities of organic small molecules for use in organic photovoltaics." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58475/.
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Organic photovoltaics (OPVs) have huge potential for competing with current inorganic photovoltaics in the search for a reliable, renewable source of energy. It is thought that only ~10 % efficiency is necessary for commercialisation and also allows avenues towards flexible, compact, lightweight optoelectronics, with current certified efficiencies already at 12%! Although the current efficiencies have surpassed expectations in order to continue the high progress new materials need to be investigated. Through understanding current materials and utilising new donor and acceptor materials the hopes of achieving higher efficiencies are realistic. Halogenation as a method to modify current organic semiconductors materials has successfully been demonstrated with minimal change to the optical properties. Successful modification of copper phthalocyanines (CuPc) to the fluorinated F16 CuPc derivative resulted in a large change in ionisation potential allowing for its use as an acceptor. This thesis will discuss the modification of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPSEpent) via chlorination in the hopes of achieving a more efficient donor material in single heterojunction devices. Through addition of electron withdrawing groups, the molecular frontier orbitals can be tuned to allow for improved stability towards C60 in solution, larger ionisation potentials which allow for larger interface gaps when used in devices, resulting in improvements in open circuit voltage (Voc), short circuit current (Jsc) and power conversion efficiency. The second part of the thesis will concentrate on the ambipolar qualities of (sub)phthalocyanines and their use as acceptors in conjunction with both the underused acene, tetracene (Chapter 5) and the more widely studied pentacene (Chapter 6). To obtain a strong understanding of using boron subphthalocyanine chloride (SubPc), Cl6-SubPc and ClAlPc as acceptors, UV –Vis absorption, atomic force microscopy (AFM), photoluminescence (PL), photoelectron spectroscopy (PES), space charge limited current (SCLC) theory to gain charge mobilities and devices were explored.
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Mitlin, Sergey. "Studies of Interaction of Small Molecules with Water Condensed Media." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/1273.
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STUDIES OF INTERACTION OF SMALL MOLECULES WITH WATER CONDENSED MEDIAThe present work reports experimental and theoretical studies of the intermolecular interactions in condensed water media. The chemical objects comprise pristine ice and polar organic substances: acetone, acetaldehyde, methanol and chloroform and bi-component water-organic deposits. The experimental part of the studies includes the Fourier Transform Infrared Reflection Absorption spectral (FTIR RAS) examination of the processes of film growth by vapor deposition on cold metal substrate and subsequent annealing. The theoretical studies include ab initio (MP2) and semi-empirical (B3LYP) calculations on the small water and water-organic clusters and classical molecular dynamics simulations of the adsorption of inert guests (Xe/Rn) on the ice surface. The FTIR RA spectral studies reveal that depending on the deposition conditions condensed water media exist in two principal structural forms: noncrystalline and polycrystalline. The former is characterized by porous structure while the latter exists as a non-porous medium with smooth external interface. On annealing, characteristic spectral changes indicate on a rapid crystallization occurring at a certain temperature range. The initial adsorption of organic molecules is accompanied by the hydrogen-bonded coordination between the functional group of organic species and non-coordinated hydroxyl group of the ice surface, the topology of which depends on the electronic properties of the functional group. The computational studies of small water-organic clusters reveal, in particular, two major coordination minima for carbonyl group: a single hydrogen-bonded in-plane complex and a double hydrogen-bonded in-plane complex. The classical molecular dynamics of Xe/Rn species on the ice interface is consistent with two distinctly different surface adsorption sites: one that delocalized over the entire surface and one that confined to small opening in the top ice layer, disrupted by the thermal molecular motion. The penetration barrier is associated with van der Walls repulsion of guest species from the ordered water hexagonal arrangement. A thermo-disruption of latter leads to a rapid diffusion of guest species inside ice medium.
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Hudon, Jonathan. "Methodologies in organic chemistry and their applications to the synthesis of bio-active small molecules." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86674.
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This thesis is separated into two parts. In part A, a novel 5-alkyl-2-silyloxy cyclopentadiene is presented. Racemic and enantioselective syntheses of the new cyclopentadiene have been developed. This new cyclopentadiene is significantly more stable towards 1,5-H shifts than most cyclopentadienes. Through the use of computational modeling, it was determined that the added stability comes from the electron donation of the 2-silyloxy group into the LUMO of the diene. The novel diene was used for Diels-Alder cycloadditions at room temperature with a variety of dienophiles. An europium Lewis acid was found to be compatible with the diene while activating dienophiles for cycloaddition. It was also determined that an enantioenriched diene will generate a cycloaddition product with no erosion in enantiomeric excess. Stabilization by a silyloxy group was also used to generate a stable 1-alkyl-3-silyloxy cyclopentadiene that underwent smooth Diels-Alder reaction. The 5-alkyl-2-silyloxy cyclopentadiene was used as a cycloaddition partner in the synthesis of part of the natural product palau'amine. Through a Diels-Alder/oxidative cleavage sequence, the E-ring stereoarray of the originally proposed structure of Palau'amine was obtained.In part B, the synthesis and purification of a novel multi-action drug, triciferol, are presented. Triciferol was designed to combine a vitamin D3 framework and a metal binding group with histone deacetylase inhibition properties. The secosteroidal core of triciferol is obtained from degradation of vitamin D2. The vitamin D A-ring is obtained from (-)-quinic acid and is appended to the core by a Horner reaction. The unsaturated side chain is built by sequential Wittig reactions and terminated by a metal-binding hydroxamic acid. This conjugated hydroxamic acid group was found to be susceptible to exposition to trace metals. The final purification of triciferol could only be accomplished using reverse phase silica chromatography. Triciferol was found to be an effective bifunctional agent, acting both as an agonist of the vitamin D receptor and an inhibitor of histone deacetylase. Moreover, it proved to be a potent anti-cancer drug in vitro.
Cette thèse comprend deux parties. Dans la partie A, un nouveau 5-alkyl-2-silyloxy cyclopentadiène est présenté. Deux synthèses de ce nouveau cyclopentadiène ont été développées : l'une racémique et l'autre énantiosélective. Le nouveau cyclopentadiène est significativement plus stable vis-à-vis de la migration 1,5 d'hydrogène que la plupart des cyclopentadiènes connus. À l'aide de la modélisation par ordinateur, la stabilité du nouveau cyclopentadiène a été attribuée à une donation électronique du groupe 2-silyloxy au LUMO du diène. Le nouveau cyclopentadiène a été utilisé lors de cycloadditions Diels-Alder à température ambiante avec une sélection de diénophiles. Un acide de Lewis à base d'europium, permettant d'activer les diénophiles sans décomposer le diène, a été trouvé. Il fut aussi déterminé qu'une version énantioenrichie du cyclopentadiène génère un produit de cycloaddition sans aucune détérioration de l'excès énantiomérique initial. La stabilisation par un groupe silyloxy a aussi été appliquée avec succès à un cyclopentadiène 1-alkyle-3-silyloxy, lui permettant d'encourir un Diels-Alder sans problème. Le 5-alkyle-2-silyloxy cyclopentadiene a été utilisé lors d'une cycloaddition menant à la synthèse d'une partie de la palau'amine, un produit naturel. La stéréochimie de l'anneau E de la structure originale de la palau'amine a été atteinte grâce à une séquence de Diels-Alder / clivage oxydatif.
Dans la partie B, la synthèse et la purification d'un nouveau médicament bi-fonctionnel, le triciferol, sont présentées. Le triciferol a été conçu afin de combiner la structure de la vitamine D3 à un groupe chélateur de métaux, ayant la capacité d'inhiber les HDAC. Le centre sécostéroïde du triciferol est obtenu par dégradation de la vitamine D2. L'anneau A est synthétisé à partir d'acide quinique et est attaché au centre sécostéroïde grâce à une réaction de Horner. La chaine insaturée est construite par réactions de Wittig et est terminée par un acide hydroxamique chélateur. Cet acide hydroxamique insaturé se décompose facilement en présence de métaux ; la purification finale du triciférol doit être effectuée par une chromatographie en phase inverse. Le triciférol a les capacité d'un médicament bi-fonctionnel : c'est un agoniste du récepteur de la vitamine D et un inhibiteur des enzymes HDAC. fr
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Galindo, Lorente Sergi. "Studies on organic solar cells based on small-molecules : tetraphenyldibenzoperiflanthene and fullerene C70." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/325421.
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This work deals with the research on organic solar cells based on small-molecules semiconductors. In particular, organic solar cells of this thesis have been used tetraphenyldibenzoperiflanthene as donor material and fullerene C70 as acceptor material.
In the first part of this thesis, we focus on the influence of the density of states of the donor layer on the characteristic parameters of solar cells. Further, organic solar cells with p-i-n structure are presented, where the intrinsic layer is obtained by coevaporation of donor and acceptor. The influence of the thickness of the intrinsic layer on the p-i-n solar cell characteristic is analysed.
In the second part, an equivalent circuit for organic solar cells is presented. A new term is added to the standard model representing recombination losses in the active layer of the device. The analysis of the characteristics of current - voltage measured at different illumination intensities allows the estimation of the term recombination. The model clearly separates technological issues (series and parallel resistance) from effects related to the physics of the device (recombination losses). It also allows obtaining an effective mobility-lifetime product in the active layer of the device to be determined, characterising its state of degradation.En aquesta tesi s’investiguen cèl·lules solars orgàniques basades en semiconductors de petita molècula. En particular, les cèl·lules solars orgàniques d’aquesta tesi han emprat tetraphenyldibenzoperiflanthene com material donador i ful·lerè C70 com material acceptador. En la primera part d'aquesta tesi, ens centrem en la influència de la densitat d'estats de la capa donadora en els paràmetres característics de les cèl·lules solars. Més endavant, es presenten cèl·lules solars orgàniques amb una estructura p-i-n, on la capa intrínseca s'obté per l'evaporació conjunta del donador i l’acceptador. S'analitza la influència del gruix de la capa intrínseca de la cèl·lula solar p-i-n en la característica de la cèl·lula solar. En la segona part, es presenta un circuit equivalent per a les cèl·lules solars orgàniques. S'afegeix un nou terme en el model estàndard que representa les pèrdues de recombinació a la capa activa del dispositiu. L’anàlisi de les característiques de corrent-tensió mesurades a diferents intensitats de llum permeten l'estimació del terme de recombinació. El model separa clarament les qüestions tecnològiques (resistències en sèrie i en paral·lel) dels efectes relacionats amb la física del dispositiu (pèrdues de recombinació). També permet l’obtenció d’un producte de la mobilitat - temps de vida efectiu a la capa activa del dispositiu a ser determinat, la caracterització del seu estat de degradació.
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Cameron, Joseph. "Small molecules based on novel electron-deficient acceptor units for organic electronic applications." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26932.
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Demand for photovoltaic cells is ever-increasing due to the diminishing supply of oil-based fuels and the associated harmful environmental effects. Organic photovoltaic devices offer a light and flexible alternative to Si-based PVs. In addition to this, they can be processed using fabrication methods such as spin-coating and inkjet printing hence, such devices have potential to be produced cheaply on a large scale. Although they have been applied as donor materials with success, polymers often show end-group variation and are polydisperse so there can be batch-to-batch variation with respect to OPV performance. A solution to these problems is the use of small donor molecules which are monodisperse and have well-defined structures. However, the shorter conjugation of small molecules with respect to polymers requires measures to shorten the HOMO-LUMO gap. A common approach is the incorporation of electron-deficient acceptor units into the donor molecule, lowering the LUMO level and therefore the HOMO-LUMO gap. Chapter 1 reviews band theory, the development of organic semiconductors, including a summary of oligothiophene based materials and common electron-deficient acceptor units used, the principles behind OPV and OFET devices and how organic semiconductors can be optimised in order to produce the best working devices. The synthesis, physical properties and OPV performance of materials based on naphthyridine-2,6-dione acceptor unit are presented in chapter 2, focussing on the difference between compounds with Donor-Acceptor-Donor and Acceptor-Donor-Acceptor structures. Chapter 3 shows the novel naphthyridin-2-one moiety and the synthesis of materials containing the unit and how they have been used for different applications including ambipolar OFETs and both donor and acceptor materials for bulk heterojunction OPV devices. A study in improving the mobility of OFET devices is presented in chapter 4. Different inorganic nanoparticles were added to organic semiconductor solutions for and the effect of this simple process on the performance of the OFET devices is discussed. Chapter 5 introduces the thieno[3,2-b]thiophene-2,5-dione and novel furo[3,2-b]furan-2,5-dione acceptor units. The synthesis, optical and electrochemical properties, and OFET and OPV device optimisation of materials based on these moieties are presented and discussed. A summary of the work discussed is presented in chapter 6 whilst chapter 7 presents the experimental methods for electrochemistry, device work, and synthetic procedures for each compound presented in Chapters 2, 3, 4 and 5.
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Yang, Kun. "CONJUGATED POLYMERS AND SMALL MOLECULES WITH LATENT HYDROGEN-BONDING FOR ORGANIC ELECTRONIC APPLICATIONS." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron149083508357808.
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Zhou, Xuan. "Structural engineering of porphyrin small molecules for bulk heterojunction organic solar cell applications." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/563.
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Organic donor and acceptor have promised the better future energy technologies to alleviate global energy demand and environmental issues. And nowadays they begin to come true in bulk heterojunction organic solar cells (BHJ OSCs) with advantages of low-cost, light-weight, large-area, flexibility, and with high efficiencies (PCEs) of over 14% for converting solar energy to electricity. Porphyrins are unique potential for artificial photocatalysis but their application in BHJ OSCs are still limited by the PCEs less than 10%. This complicacy comes from their inadequate spectral absorptions and the imperfect morphologies. In this thesis, we devote to chemical modification of acceptor-π-porphyrin-π-acceptor (A-π-Por-π-A) structural molecules to enhance their spectral absorptions and phase-separation functions with fullerene acceptor. Firstly, chemically driving J-aggregates have been studied on the new A-π-Por-π-A porphyrin molecule, which could improve the phase-separation of its blend film with PC71BM and and enhance its performance in BHJ OSCs with PCE up to 8.04%. Secondly, two new benzodithiophene (BDT) π-bridged A-π-Por-π-A molecules have been prepared with complementary absorption between the Soret and Q bands. The devices based on the blend fims of the porphyrin donor and PC71BM acceptor exhibit full spectral photocurrent generation and impressive PCEs up to 7.92%. Thirdly, we further extended the π-conjugation of the above BDT π-brigded A-π-Por-π-A molecules by inserting alkyl chain substituted thiophene derivatives into their backbones, resulting in new porphyrin molecules with UV-visible-near-infraed absorption spectra. Using those porphyrin molecules as donor and PCBM as acceptor, the devices show full spectra photocurrent generatoion and appropriate film morphology, resulting in high PCE up to 8.59%. Besides, photocatalysis is also a new promising technology to generate renewable energy. We herein develop new low-cost and noble-metal-free photocatalysts based on Co(OH)2 modified CdS nanowires and applied them for visible light driven hydrogen production from water-splitting. The optimum H2 production rate reaches 14.43 mmol·h−1·g−1 under (λ ≥ 420 nm) upon visible light irradiation, which is 206 and 3 times larger than that of the pristine CdS NWs and 1 wt% Pt-CdS NWs, respectively. The results indicate the promising application of earth-abundant Co(OH)2 as alternative cocatalysts of noble metals.
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Lu, Yuhua. "POLYMERIC REAGENTS IN SOLID-PHASE SYNTHESES OF SMALL MOLECULES AND DENDRIMERS." Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1091730351.
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Chapman, James Vincent III. "Design and Synthesis of Organic Small Molecules for Industrial and Biomedical Technology Nanomaterial Augmentation." Thesis, University of Colorado at Denver, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10272651.
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Organic chemistry used to augment nanoparticles and nanotubes, as well as more traditional materials, is a subject of great interest across multiple fields of applied chemistry. Herein we present an example of both nanoparticle and nanotube augmentation with organic small molecules to achieve an enhanced or otherwise infeasible application. The first chapter discusses the modification of two different types of Microbial Fuel Cell (MFC) anode brush bristle fibers with positive surface charge increasing moieties to increase quantitative bacterial adhesion to these bristle fibers, and therefore overall MFC electrogenicity. Type-1 brush bristles, comprised of polyacrylonitrile, were modified via the electrostatic attachment of 1-pyrenemethylamine hydrochloride. Type-2 brush bristles, comprised of nylon, were modified via the covalent attachment of ethylenediamine. Both modified brush types were immersed in an E. Coli broth for 1 hour, stained with SYTO® 9 Green Fluorescent Nucleic Acid Stain from ThermoFisher Scientific (SYTO-9), and examined under a Biotek Citation 3 fluorescent microscope to visually assess differences in bacterial adherence. In both trials, a clear increase in amount of bacterial adhesion to the modified bristles was observed over that of the control. The second chapter demonstrates a potential biomedical technology application wherein a polymerizable carbocyanine-type dye was synthesized and bound to a chitosan backbone to produce a water-soluble photothermal nanoparticle. Laser stimulation of both free and NP-conjugated aqueous solutions of the carbocyanine dye with Near-Infrared (NIR) Spectrum Radiation showed an increase in temperature directly correlated with the concentration of the dye which was more pronounced in the free particle solutions.
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Onaran, Mehmet B. "Design and synthesis of bioactive small molecules and high-throughput identification of enantiomeric excess." View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319114.
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Scott, Benjamin M. T. "From small molecules to nano-scale architectures - a supramolecular approach." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/612.
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Müller, Toni. "Infrared Absorber Materials in Organic Small Molecule Solar Cells." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-178375.
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Broadening the spectrum available to solar cells towards infrared wavelengths is one way to increase efficiency of organic solar devices. This thesis explores the possibilities of these organic heterojunction devices and two different material classes in thin films and organic solar devices: tin phthalocyanines (SnPcs) and aza-bodipys. To estimate the efficiency reachable under sunlight, model calculations are done for single and tandem cells. These calculations include a distinction between the optical gap and the electrical gap and the splitting of the quasi-Fermi levels. With a number of assumptions, e.g. a fill factor (FF) and an external quantum efficiency (EQE) within the absorption range of 65%, the resulting efficiencies are 15% in a single cell and of 21% in a tandem cell. Halogenation is known to lower the energy levels of molecules without chang-ing the optical band gap. Three different fluorinated and chlorinated SnPcs are investigated and compared to the neat SnPc. While chlorination of SnPc worsens the transport properties of the active layer leading to a lowered FF, the fluorina-tion of SnPc results in the intended increase in VOC and, consequently, efficiency for planar heterojunctions. In bulk heterojunction, however, fluorination does not change the efficiency probably due to the unstably bound fluorine. One method to modify the ionization potential (IP) and the absorption of the second material class, the aza-bodipys, is the annulation of the benzene ring. The energy levels determined by CV and UPS measurement and DFT-calculation show very good agreement and can be linked to a decrease in VOC: The Ph4-bodipy (not benzannulated) device has an efficiency of 1.2% with an EQE reaching up to 800nm and a VOC of almost 1V. The Ph2-benz-bodipy device shows a Voc of 0.65V and an efficiency of 1.1%, the EQE reaching up to 860nm. The variation of the molecule’s end groups to vary their IP is successfully employed for three different benz-bodipys: The variation results in a decrease of the optical gap from 1.5eV for the phenyl group, to 1.4eV for the MeO group, and 1.3eV for the thiophene group with the effective gap and the VOC following this trend. Efficiencies of 1.1% and 0.6% in combination with C60 can be reached in mip-type devices. Ph2-benz-bodipy is then optimized into a single cell with an efficiency of 2.9%. In a tandem cell with DCV6T-Bu4:C60, a Voc of 1.7V, a FF of 57% and an efficiency of 5% is reachedDie Erweiterung des verfügbaren Spektrums in den Infrarotbereich ist eine Möglichkeit, die Effizienz organischer Solarzellen zu erhöhen. Diese Arbeit erkundet das Potential dieser Heteroübergänge und zwei Materialklassen in dünnen Schichten und Bauelementen: Zinnphthalozyanine (SnPc) und aza-Bodipys. Um die potentielle Effizienz abzuschäötzen, werden Modellberechnungen für Einzel- und Tandemzellen durchgeführt, unter Berücksichtigung des Unterschieds von optischer und elektrischer Bandlücke und der Quasiferminiveauaufspaltung. Mithilfe einiger Annahmen (z.B. Füllfaktor (FF) und externe Quanteneffizienz (EQE) gleich 65%) lässt sich die Einzelzelleffizienz auf 15%, die Tandemzelleffizienz auf 21% abschätzen. Halogenierung kann die Energieniveaus organischer Moleküle herabsetzen, ohne die optische Bandlücke zu verändern. Drei verschiedene chlorierte und fluorierte SnPcs werden mit dem reinen SnPc verglichen. Während die Chlorierung die Transporteigenschaften der aktiven Schicht und den FF verschlechtern, erhöht die Fluorierung wie erwartet Leerlaufspannung (VOC) und Effizienz im flachen Übergang, nicht jedoch in der Mischschicht, vermutlich aufgrund des nicht stabil gebundenen Fluors. Ein Weg, Ionisationspotential (IP) und Absorption der aza-Bodipy zu verändern, ist die Anelierung des Benzenrings. Die durch CV und UPS ermittelten und mittels DFT errechneten Energieniveaus stimmen gut überein und führen zu einer Verringerung der VOC: Die Zelle mit nichtaniliertem Ph4-bodipy zeigt eine Effizienz von 1.2%; das EQE reicht bis 800nm, die VOC beträgt fast 1V. Die Ph2-benz-bodipy-Zelle zeigt eine VOC von 0.65V und eine Effizienz von 1.1%, das EQE reicht bis 860nm. Der Austausch der Endgruppen zur Vergrößerung des IP, erfolgreich angewandt auf drei Benz-Bodipy-Verbindungen, führt zu einer Verringerung der optischen Bandlücke: von 1.5eV (Phenyl) über 1.4eV (MeO) zu 1.3eV (Thiophen); effektive Bandlücke und Voc folgen diesem Trend. Effizienzen von 1.1% und 0.6% in Kombination mit C60 werden in mip-Zellen erreicht. Ph2-benz-bodipy zeigt in einer optimierten nip-Zelle sogar eine Effizienz von 2.9%. Eine Tandemzelle mit DCV6T-Bu4:C60 zeigt eine Voc von 1.7V, einen FF von 57% und eine Effizienz von 5%
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BARRETO, ARTHUR RODRIGUES JARDIM. "DEVELOPMENT AND CHARACTERIZATION OF ORGANIC LIGHT-EMITTING TRANSISTORS (OLETS) BASED ON CONJUGATED SMALL MOLECULES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35241@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho teve como objetivo fabricar e caracterizar Transistores Orgânicos Emissores de Luz (OLETs, Organic light-Emitting Transistors). Os OLETs combinam em um único dispositivo a funcionalidade elétrica de um transistor de efeito de campo orgânico e a capacidade de geração de luz, representando uma nova classe de dispositivos orgânicos com alto potencial de inovação em aplicações, como sistemas ópticos de comunicação, tecnologia de displays avançada, lasers orgânicos, fontes de luz em nanoescala e optoeletrônica orgânica integrada. Portanto, esta tese possui um caráter pioneiro, tanto para grupo de pesquisa quanto para o país, uma vez que ocorre a junção dos conhecimentos e domínio adquiridos sobre OFETs e OLEDs. Efetivamente, este trabalho de doutorado consistiu na fabricação e caracterização sistemática de diversos dispositivos OLET utilizando variadas arquiteturas e diversos materiais, comerciais e não comerciais, como o NT4N, o P13 e uma bicamada de C8-BTBT com TcTa:Ir(ppy)3. Os dispositivos foram caracterizados através de medidas elétricas e óticas, obtendo-se as curvas características. Também foram determinados seus parâmetros e propriedades de funcionamento, com destaque para as mobilidades de carga e para as eficiências obtidas. Houve também o entendimento e a implementação de um tratamento térmico na camada dielétrica, sendo parte fundamental da fabricação dos dispositivos. Os dispositivos fabricados apresentaram diferentes graus de desempenho, com destaque para a arquitetura bicamada, por apresentar a maior potência luminosa (4 microwatt) e a maior eficiência (0,5 por cento), sendo suficientes para inserir os dispositivos fabricados na categoria de dispositivos orgânicos altamente eficientes. Tal fato demonstra que o domínio da fabricação e da caracterização desta nova classe de dispositivos foi alcançado.
The aim of this work was to achieve the knowledge of the fabrication and the characterization of Organic Light Emitting Transistors, OLETs, considered as one of the innovative technologies nowadays. The OLETs combine in a single device the electrical functionality of an organic field-effect transistor (OFET) and the light-generating capability. They represent a promising new class of organic devices with high potential for innovation in applications such as communication systems, advanced display technology, organic lasers, nanoscale light sources and integrated organic optoelectronics. In some way, this thesis has a pioneer character, both for our research group and for the country, since it combines different knowledge and skills about OFETs and OLEDs to achieve a new device. Actually, this work involved the systematic manufacture and characterization of several OLETs using different architectures employing commercial and noncommercial materials, such NT4N, P13 and a bilayer of C8-BTBT with TcTa:Ir(ppy)3. The devices were then characterized by electrical and optical measurements. The working parameters and properties were determined as well, highlighting the charge carrier mobilities and efficiencies obtained. The understanding and the implementation of a specific heat treatment in the dielectric layer was a fundamental part of this work for the manufacture of the devices which have different degrees of performance. With emphasis on the bilayer architecture, that presented the highest luminous power (4 microwatt) and efficiency (0,5 percent), inserting the devices manufactured in the category of highly efficient organic devices. Such fact shows that the fabrication and characterization of this new class of devices has been achieved.
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Fontanive, Giampaolo. "Libraries of short receptors peptides and antibodies for the recognition of small organic molecules." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3612.
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2008/2009La presente tesi di Dottorato riporta i risultati di ricerche svolte nell’ambito di alcune collaborazioni tra Università ed industria nel campo della progettazione e sviluppo di librerie di trasduttori primari per biosensori. In particolare l’attenzione si è rivolta da un lato a piccoli peptidi come recettori di xanthine (caffeina e teofillina), dall’altro ad una molecola di grandi dimensioni, la palitossina, verso la quale al momento sono stati preparati anticorpi con tecniche più convenzionali. Il contributo di un chimico in questo tipo di progetti è analogo, e consiste in un’attività di sintesi di derivati modificati delle molecole di interesse, nella loro bioconiugazione a proteine ed enzimi, nella sintesi di peptidi, nello studio dell’interazione ligando-recettore attraverso misure di attività, analisi conformazionale e strutturale, modellizzazione. L’attività svolta è brevemente descritta nei punti seguenti. 1) I coiled-coil sono motivi strutturali presenti in natura dati dall’unione di due o più -eliche avvolte su loro stesse al fine di generare un’unica super-elica. L’analisi di tali strutture rivela spesso la presenza di sequenze ripetute di 7 amminoacidi ripetuti (g-a-b-c-d-e-f) con precise caratteristiche: la posizioni a e d per esempio sono occupate sempre da amminoacidi con caratteristiche idrofobiche, atti a generare una interfaccia idrofobica interna alla super-elica molto stabile e non esposta al solvente esterno. Parallelamente, le posizioni e e g sono invece occupate da amminoacidi polari carichi che si trovano sulla superficie esterna della super-elica e possono iteragire tra di loro rinforzando l’interazione e provocando effetti di orientamento. La nostra attenzione si è focalizzata sul coiled-coil denominato EK, sviluppato agli inizi degli anni ’90 da Hodges e colleghi. In questa struttura due catene peptidiche denominate appunto E e K si avvolgono su loro stesse al fine di generare una super-elica anfipatica di notevole stabilità.Partendo da tale struttura e sfruttando la tecnica biomolecolare del phage display che permette l’esposizione di strutture a carattere proteico sulla superficie di un batteriofago, sono state create librerie di EK mutati con l’obiettivo di generare all’interno della super-elica siti recettoriali eventualmente utilizzabili all’interno di biosensori come trasduttori primari per caffeina e teofillina, due piccole molecole organiche altamente correlate e ampiamente presenti nella vita quotidiana. E’ stata prodotta una prima libreria fagica di dimensioni notevoli (108 elementi), all’interno della quale sono stai isolati due cloni specifici per le xanthine; i due cloni sono stati denominati E1 ed E8. La caratterizzazione del binding è avvenuta sia con tecniche biomolecolari che prevedono l’immobilizzazione dell’analita su superficie solida (test ELISA e dot-blot), sia con teniche chimiche con analiti liberi e privi di modificazioni strutturali. Al fine di ridurre il più possibile le dimensioni dello scaffold di partenza è stata sviluppata una seconda libreria fagica in cui è stata randomizzata soltanto la catena K dell’originario EK proposto da Hodges. La libreria finale presenta una dimensione di 108 elementi, tra i quali è stato isolato e caratterizzato attraverso test ELISA il clone denominato KE1. Le ridotte dimensioni di tale peptide (35 amminoacidi) hanno permesso la sua sintesi chimica su una buona scala (40 mg), una cartterizzazione strutturale attraverso spettroscopia di dicroismo circolare, un’analisi dell’interazione in soluzione con la teofillina sfruttando sempre la tecnica CD e quella calorimetrica ed infine un’analisi cristallografica attraverso luce di sincrotrone. 2) Una seconda parte del lavoro è stata finalizzata, invece, allo sviluppo di pool anticorpali mono- e policlonali quali trasduttori primari in biosensori per l’individuazione della palitossina. Tale tossina algale con elevato indice di pericolosità (LD50=0.45 g/kg) negli ultimi anni ha causato notevoli disagi in campo ambientale, inquinando flora e fauna acquatica di diverse zone marittime, compreso il Mediterraneo e l’alto Adriatico. Per lo sviluppo di anticorpi specifici contro tale tossina, sono state condotte immunizzazioni su coniglio e su topo con palitossina coniugata a due tipi di proteine carrier (BSA e KLH) al fine di ridurre la sua tossicità e indurre una risposta immunitaria nell’animale. Il pool anticorpi policolnali di siero di coniglio è stato isolato e caratterizzato attraverso sandwich ELISA contro palitossina libera e palitossina chimicamente modificata allo scopo di ottimizzare tale tipo di test e utilizzarlo come possibile dosatore nei confronti dell’analita presente in campioni di acqua oppure in sistemi più complessi quali mitili o ulteriore fauna marina.
This PhD thesis reports the results of research activities carried out at the Dept. of Chemistry of the University of Trieste, in collaboration with several industries, in the field of design and development of libraries of primary transducers for biosensors. We have focused our attention on one side on short peptides as xanthine (caffeine and theophylline) receptors, and on the other side on a very large molecule, palytoxin, which has been considered to raise antibodies by more conventionals techniques. The chemist’s contribution to such projects is similar, consisting in the synthesis of modified target molecules, in their bioconjugation to protein and enzymes, in peptide synthesis, in studying the receptors-ligand interactions by affinity measurements, conformational and structural analysis, modelling. The activity is briefly described in the following points. 1) Coiled-coil are natural motifs made by bundles of two or more -helix that generate a super-helix. Structural analysis of these motifs reveals often the presence of a repeated sequence 7 aminoacids along the helix (g-a-b-c-d-e-f). a and d are hydrophobic aminoacids able to generate an internal hydrophobic core most important for the overall stabilization of the bundle, e and g are polar or charged aminoacids that can contribute to the final stability of the coil via electrostatic interchains interactions. Starting from the EK coiled-coil developed by Hodges et al., made by two different peptide chains (E:EVSALEK; K:KVSALKE) and exploiting phage display techniques, two different phage libraries of E and K mutants were generated, in order to obtain receptors molecules suitable as primary transducer in biosensors for caffeine and theophylline. In the first library, both E and K were randomized, obtaining 108 differents peptide clones; two specific clones was isolated against immobilized caffeine and theophylline, their characterization was carried out both by biomolecular experiments (ELISA test; dot-blot) and by chemical techniques. In a second library, we have further reduced the scaffold size, using only a single K chain. A new library of 108 elements was obtained and characterized. The isolation of KE1 clone as the best xanthine binder, allowed chemical synthesis on a good scale (40 mg); structural characterization and binding analysis of its interaction with theophylline in water was performed by circular dichroism and calorimtrey; the X-ray structure of the peptide was obtained exploiting sincrothrone light. 2) In a second part of this work, the development of mono- and polyclonal antibodies towards palytoxin was stated. Palytoxin is one of the most dangerous algal toxin in nature (LD50=0.4 g/kg in mice) and its presence in the last years in Mediterranean sea, both in the water sea and in fish or mussels, constitues a real problem for tourism economy and for the fish market. In order to obtain specific antibodies as bioreceptors towards palytoxin, a series of immunizations on rabbits were carried out with palytoxin-BSA and palytoxin.KLH conjuagtes in order to generate immune response in the animals; the pool of high reactivity bleeds of rabbits, were isolated and usedto set up ELISA sandwich system towards palytoxin.
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Le, Borgne Mylène. "Solution-processable oligomeric and small molecule semiconductors for organic solar cells." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0048/document.
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Les cellules solaires organiques sont une technologie très prometteuse grâce à leur faible-coût de fabrication, leur flexibilité et leur légèreté. Actuellement, elles ne sont qu’au stade du prototype à cause de leurs faibles rendements et leur courte durée de vie. L’une des voies les plus étudiées pour améliorer le rendement est la conception de nouveaux matériaux photo-actifs. Lors de cette thèse, deux séries de semi-conducteurs donneurs d’électrons. La première série comprend trois oligomères, chacun composé de trois unités de diketopyrrolopyrrole (DPP) qui est un chromophore très étudié dans la littérature. Ces oligomères ont la particularité d’absorber dans le proche infra-rouge. En intercalant différents groupements donneurs d’électrons entre les DPPs, différentes torsions sont obtenues le long de leur squelette. Ceci a permis d’établir qu’un oligomère plan a une plus grande cristallinité et par conséquent transporte mieux les charges, atteignant une mobilité de trou de 10-3 cm². V-1.s-1. Cependant, cette forte cristallinité entraîne une hétérojonction volumique défavorable et un faible rendement photovoltaïque (<1%). La deuxième série est composée de quatre petites molécules combinant une unité 3,3’-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI) avec différents groupements donneurs d’électrons: thiophène (EBI-T), benzofurane (EBI-BF) and bithiophène (EBI-2T)). Les dérivés EBI ont été testés dans les transistors à effet de champ et dans les cellules solaires en tant que semi-conducteurs donneurs. La meilleure mobilité de trou de 0,021 cm².V-1.s-1 a été mesurée avec EBI-BF grâce à sa conformation plane alors que le PCE maximal de 1.92% est obtenu avec EBI-2T grâce à son large spectre d’absorption et une morphologie adéquateOrganic solar cells appear as a promising technology within photovoltaic field owing to their low-cost fabrication and their great flexibility enabling a widespread distribution. For now, they are still at the prototype stage due to their limited efficiency and lifetimes. Many efforts were realized in designing new materials as they are involved in every steps of the photovoltaic process and thus they dictate the cell efficiency. Along this thesis, two series of electron-donating semi-conductors were designed and synthesized. The first series consist in three oligomers containing three diketopyrrolopyrrole units, a well-studied chromophore. Those oligomers absorb up to the near infra-red region, a very interesting feature for light harvesting. Through the engineering of electron-rich spacers, various twists were generated in the oligomers backbone. The oligomer showing a coplanar conformation appears to be the most crystalline and thus exhibits the best charge transport properties with a hole mobility of 10-3 cm².V-1.s-1.iiiHowever, bulk heterojunction organic solar cells, this high crystallinity results in an unfavorable morphology and a PCE inferior to 1%. As for the second series, the four small molecules combined 3,3’-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI), an electron deficient unit, and various electron-rich units such as thiophene (EBI-T), benzofuran (EBI-BF) and bithiophene (EBI-2T). Among EBI derivatives, EBI-BF demonstrated the highest hole mobility of 0.021 cm².V-1.s-1 in field effect transistors due to its coplanar conformation. Meanwhile, in bulk heterojunction solar cells, the highest PCE of 1.92% was obtained with EBI-2T:PC61BM blend owing to a more appropriate morphology and the broadest absorption spectrum of EBI-2T
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Singsumphan, Kittiyaporn. "Correlation between morphology and optical properties of blends of small organic molecules and thermoplastic polymers." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580346.
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Organic small molecules, especially oligoacene derivatives, have been used for electronic devices, such as field-effect transistors (FET), because of their high solubility in organic solvents and chemical stability. Blends of acene derivatives within a polymer matrix have generated interest as a means to combine the carrier mobility of small molecules with the attractive properties of polymers. This blend system provides high performance with ease of processing and mechanical robustness. Whereas most previous work has considered acenes for transistors, this current research investigates the properties of acene/polymer blends as candidate materials for lasers. Specifically, we correlate the photoluminescence (PL) of blends of acene and glassy polymers with microstructure, as it is influenced by the selection of solvent and processing conditions. 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) and polystyrene were blended in an organic solvent, tetralin with one of two different grades: anhydrous and reagent-grade. It was discovered that the grade of the solvent and the age of the solution prior to film deposition have a pronounced impact on the degree of TIPS-pentacene crystallinity. Film deposition from solutions in the anhydrous solvent resulted in large, needle-like TIPS-pentacene crystals. On the other hand, the use of the reagent grade-solvent leads to a loss in crystallinity. The size and amount of crystals decrease as the reagent-grade solution ages over time. Specifically, the PL intensity from films cast from reagent-grade solutions (aged for 22 hours) was significantly stronger (by a factor of 100) than a solution of the same age cast from anhydrous solvent. 9, 10-bis(triethylsilylethynyl) anthracene (TES-anthracene) and TES-anthracene/polystyrene blends were investigated for the first time in this research. It was discovered that the preparation method and the processing conditions have a significant influenced on the quantum efficiency (QE) of the blend films. The polymer dynamics adjusted by the PS Mw do not have much effect on QE. Solvent-cast films present dendritic crystals that exhibit a QE of ea. 10-15%. In contrast, after a newly-developed melt-processing method, films exhibit more dense crystals with a lack of order in TES-anthracene crystal arrangement. Interestingly, films made with low Mw polystyrene by melt- processing (160 QC with 5 min. hold time) show a disordered arrangement of crystals and exhibit the strongest QE of 20%. These results provide a means to adjust the microstructure of small molecule/polymer blends and thereby to adjust their performance in lasing applications.
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Belcher, David Eric. "A study of gas-phase solvation of small organic molecules using high-resolution laser spectroscopy." Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399624.
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Sahotra, Nikhil. "Design and synthesis of organic small molecules with high triplet energy for blue light emission." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8096/.
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For the past two decades, organic light emitting diodes (OLEDs) have been the subject of intense research in the realm of display and lighting applications. Recently, thermally activated delayed fluorescence (TADF) has shown great potential in further advancing OLED technology. In order to achieve TADF, synthesis of acceptor and donor compounds has been undertaken to achieve exciplex formation. Little is currently known about exciplex formation and emission, so systematic structural variations have been performed on MCP and DPBI in order to gain fundamental knowledge. Compound analyses were performed in both the solid and solution state. In the case of MCP derivatives, demonstration of their ability to act as an acceptor is possible, alongside an appropriate choice of donor molecule. Reducing the extent ofconjugation in derivatives of DPBI, did not result in an increase in triplet energy. Consequently, to eliminate possible conformers, steric blocking was introduced in an attempt to increase the triplet energy. In the case of the ME-DPBI derivative it was shown possible to formulate a device showing 2.5% external quantum efficiency while emitting at ~450 nm which is a true blue colour.
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Gemeinhardt, Chelsea Nicole. "DFT STUDIES OF SMALL ORGANIC MOLECULES FOR APPLICATIONS IN MALDI MASS SPECTROMETRY AND SOLAR CELLS." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1752.
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The focus of the work presented herein is to understand the underlying photoexcitationprocesses of small organic molecules for applications in MALDI mass spectrometry and solarcell applications through computational methods. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) calculations were performed to provide insightinto the effect of heavy atom substitution on the charge transfer properties of MALDI matrixmolecules as well as understand the underlying photophysical properties of rationally designedorganic molecules for use in Dye Sensitized Solar Cells (DSSCs) and Organic Solar Cells(OSCs).Fifth and sixth carbon ring substituted isomers of fluorinated, chlorinated, andbrominated isomers of 2,4-dihydroxybenzoic acid and their thermodynamic and photophysicalproperties were examined to understand the effect of halogenation of MALDI matrix molecules.Thermodynamics studies included the calculation of Proton Affinity (PA), Gas Phase Acidity(GPA), and Gas Phase Basicity (GPB). PA values suggested that nearly all halogenated matricesat the ground electronic state became less acidic than its unsubstituted counterpart. Additionally,the GPA values of the unsubstituted isomer revealed that the order of acidity of protons is thecarboxylic acid proton, followed closely by the two phenolic protons. Following fifth ringsubstitution, the carboxylic acid clearly became to most acidic, followed by the second phenolicproton, and lastly the fourth phenolic proton while for the sixth ring substitution, the carboxyliciiacid and second phenolic group yield similar thermodynamic values, but the fourth phenolic group has the most basic GPA value.Comparison of the UV-Vis absorbance spectra generally showed increased absorbance at λmax compared to the unsubstituted isomer, and most importantly, absorbance at MALDI laser excitation wavelength of 337nm increases after halogenation in almost all cases of halogen substitution. An increase in overlap between the absorbance and emission spectra (Stokes shift) occurred after fifth carbon ring halogenation, but not for sixth ring suggesting that the addition of a halogen on the fifth carbon of the aromatic ring results in stokes shiftan overall more rigid molecular structure, while sixth carbon substitution does not.The bond distances, angles, and Mulliken charges for the ground and excited states were tabulated and compared to understand the structural impact of halogenation at two different ring positions, which showed that not only does the exact location of the halogen affect the structure in unique ways, but also the specific identity of the attached halogen.The HOMO-LUMO contours, energies, and gaps were also obtained in the ground, first excited singlet, and triplet states for both sets of isomers. Contours were examined to quantify the role of the halogen as an electron withdrawing group, where the location of the halogen atom, and its identity, leads to different configurations of electron density. The energies of these orbitals are raised or lowered depending on the location of the halogen on the fifth or sixth carbon and whether the molecule is in the ground or excited state.IR spectra were compared for the ground, the first excited singlet, and triplet states to further elucidate the effect of halogenation on the stretching modes of the protons of interest in charge transfer during MALDI. In both fifth and sixth carbon ring substitutions in the groundiiistate, the carboxylic acid proton stretch is not affected while the phenolic protons were to varying degrees.Most interestingly is that, in the singlet state, the second phenolic stretching mode is largely weakened following nearly all halogenation at the fifth and sixth carbon ring position, which may play a role in stabilizing the carboxylate anion left after charge transfer occurs via an intramolecular hydrogen bond. Conversely, in the triplet state, halogenation on the sixth carbon ring position results in a decreased frequency intensity as well as bond strengthening for chlorine and bromine and weakening for fluorine. This in contrast to 5-X-2,4-DHB substitution, where all halogenation weakens the second phenolic group.Short-lived charged states in simple organic donor−acceptor (D−A) systems were also studied as huge improvements are needed to produce efficient photovoltaic devices. One strategy implemented in this work was to prevent back-electron transfer by forming a cascade of energy levels through the use of a donor−acceptor 1−acceptor 2 (D−A1−A2) architecture , where three systems YD-TRC, YD-TRC-AEAQ, and MHTPP-TRC-AEAQ were characterized in depth via computational and experimental methods.The DFT results indicated that YD-TRC could form a D–A1 system, YD-TRC-AEAQ, a D–A1–A2 system, and MHTPP, a D-L-A system. Computational predictions were confirmed via electrochemical measurements included in the Appendix of this work. Ambipolar systems were synthesized, as the HOMO energy of YD and MHTPP were both higher than the HOMO of AEAQ. Furthermore, the red shift exhibited in UV-vis absorption after YD was connected its first acceptor to form YD-TRC was confirmed by computational analysis as an intramolecular charge transfer.ivWhile these studies showed that the addition of a second acceptor extended the lifetime compared to its dyad counterpart, large amounts of energy are still lost during each sequential electron transfer process, as well as the difficulty of synthesizing these molecules in the laboratory. To remedy both concerns, another viable strategy involves designing simple, small Donor-Acceptor (D-A) systems with long charge separation and slow charge recombination.The effect of donor molecules on the compound’s photophysical properties was explored, by selecting multiple donor modules and keeping the accepter the same as used in previous studies. TPA and PCB donors were proposed, and the following compounds were obtained: TPA-TRC and PCB-TRC, respectively. Additionally, dimethoxy groups and dioctyloxy groups were introduced to TPA-TRC, forming the derivatives MeTPA-TRC and OeTPA-TRC, respectively, to be added to this work.In addition to confirming that these compounds are truly arranged in the typical D-A structure based on their orbital energies, we also showed that the HOMO and LUMO are located at the donor module and TRC module, respectively. Most interestingly, the LUMO and LUMO+1 energy levels of these studied systems remained essentially unchanged, while the HOMO energies were impacted, where donor modules with stronger electron donating abilities have stronger effect on the HOMO levels.This work serves to highlight the importance of utilizing computational chemistry throughout the design, screening, and application of small organic dyads and triads toward solar cell applications. As demonstrated, calculations provide insight into the optically active molecular orbitals responsible for electronic transitions, such as those within the UV-Vis range for solar cell applications while the corresponding energies of these same orbitals can be used to accurately screen a potential system for true D-A or D-A1-A2 character.
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Ndoye, Chérif A. A. "Electronic spectroscopy of small organic and organometallic molecules : electronic correlation, vibronic and spin-orbit couplings." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/NDOYE_Cherif_AA_2008.pdf.
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La prédiction de propriétés spectroscopiques moléculaires et l’interprétation de spectres expérimentaux nécessitent de faire appel à la théorie. Une première étape consiste à se limiter à la spectroscopie électronique dans l’approximation de Born-Oppenheimer ce qui consiste à considérer les noyaux de la molécule comme étant fixes et les états électroniques indépendants les uns des autres. L’objectif de cette thèse est d’étudier la structure électronique de petites molécules organiques et organométalliques dans l’approximation de Born-Oppenheimer dans un premier temps avant d’aller au delà en prenant en compte des effets tels que le couplage vibronique ou le couplage spin-orbite entre les états électroniques. Le premier chapitre est consacré aux méthodes ab initio utilisées pour obtenir les résultats présentés dans les chapitres ultérieurs. Une première partie est consacrée aux méthodes de structure électronique dans l’approximation de Born-Oppenheimer, elle est suivie d’une partie qui traite des effets de couplage vibronique et spin-orbite. Le second chapitre présente une étude de la structure électronique et des courbes d’énergie potentielle des carbènes de métaux de transition MCH+2 (M=Fe, Co, Ni). Le troisième chapitre rapporte les spectres vibroniques des fluoroéthylènes obtenus par simulation et comparés aux spectres expérimentaux afin d’identifier l’origine de différentes contributions spectroscopiques. Enfin le dernier chapitre traite des effets spin-orbite dans l’eau et ses homologues lourds (H2X avec X=O, Te, Po)Theory is sometime necessary to predict molecular spectroscopic properties and interpret experimental spectra. A first step study can be limited to the electronic spectroscopy in Born-Oppenheimer approximation which consists in considering nuclei fixed and electronic states independent from each other. The scope of this thesis is to first study the electronic structure of small organic and orgnometallic molecules in the Born-Oppenheimer approximation and ultimatly go beyond by taking into account effects such as vibronic or spin-orbit couplings between electronic states. The first chapter is dedicated to the ab initio methods used to obtain the results presented in the following chapters. Electronic structure methods in the Born-Oppenheimer approximation are first presented followed by the methods that treat vibronic and spin-orbit couplings. The second chapter is a study of the electronic structure and potential energy curves of MCH+2 (M=Fe, Co, Ni) transition metal carbenes. Chapter three reports simulated vibronic spectra of fluoroethylenes, they are compared to experimental spectra to indentify the origin of the different spectroscopic contributions. A last chapter deals with the spin-orbit effects in water and its heavy homologous (H2X with X=O, Te, Po)