Дисертації: "Photophysical Studies - Organic Molecules"

1

Chin, Khin Kein. "Photophysical studies of fullerene derivatives and organic molecular nanocrystals ; and Singlet oxygen in microheterogeneous media: direct characterization in zeolites, proteins, and immunoglobulins." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1779690191&sid=7&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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2

Rubio, Pons Oscar. "Photophysical Properties of Organic and Organometallic molecules." Licentiate thesis, KTH, Biotechnology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1739.

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Highly correlated quantum chemical methods have been appliedto study the photophysical properties of substituted benzenes.With the inclusion of spin-orbit coupling, the phosphorescencesof these molecules have been calculated usingMulti-CongurationalSelf- Consistent Field (MCSCF) quadraticresponse theory. The Herzberg-Teller approximation has beenadopted to evaluate the vibronic contributions tophosphorescence.

The performance of hybrid density functional theory (DFT) atthe B3LYP level is examined in comparison to the MP2, CCSD andCCSD(T) methods for the geometry and permanent dipole moment ofp-aminobenzoic acid. The time-dependent DFT/B3LYP method isapplied to calculate the two-photon absorption of a series ofZinc-porphyrin derivatives in combination with a two-statemodel. The transitions between excited singlet and tripletstates of Zinc and Platinum based organometallic compounds havebeen computed using DFT quadratic response theory. The resultsare used to simulate the non-linear propagation of laser pulsesthrough these materials utilizing a dynamical wave propagationmethod.

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3

Jones, Derek R. "Design, Synthesis, and Photophysical Properties of Corannulene-based Organic Molecules." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1323350004.

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4

Law, Ga-lai. "Synthesis and photophysical studies of organic lanthanide complexes." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38308216.

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5

Law, Ga-lai, and 羅嘉麗. "Synthesis and photophysical studies of organic lanthanide complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38308216.

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6

Rogge, Carsten. "Photophysical studies of organic dyes in polymer matrices." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266485.

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7

Wong, Ka-Leung. "Synthesis, characterization, and photophysical studies of organic-lanthanide complexes." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36875351.

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8

Wong, Ka-Leung, and 黃嘉良. "Synthesis, characterization, and photophysical studies of organic-lanthanide complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36875351.

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9

Chretien, Michelle N. "Photochemical, photophysical, and photobiological studies of zeolite guest-host complexes." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/29205.

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This thesis focuses on the photochemistry and photophysics of a variety of zeolite complexes, from catalysts to sunscreens. The first chapter describes the preparation and photophysical and photochemical characterization of two new photocatalytic materials. The catalysts are based on a multi-component zeolite, host-guest complex and the interaction between components was probed using time-resolved spectroscopic techniques. The catalytic efficiency, in terms of the ability to photodegrade biological contaminants, was also investigated. These studies were performed with the aim of developing efficient catalysts for wastewater remediation which can be used with solar (visible) radiation. In subsequent chapters, zeolite materials have been used as matrices for the stabilization of various transient or reactive species. In the case of ZSM-5-type zeolite, the dibenzotropylium cation was rendered indefinitely persistent allowing the examination of its excited-state behaviour. The geometric restriction within the cavities also permits the observation of electron transfer chemistry in the absence of a nucleophilic addition reaction with the electron donor. In a second example, ketoprofen (a non-steroidal anti-inflammatory drug) was found to undergo intrazeolite photodecarboxylation to generate a benzylic carbanion. The lifetime of the zeolite-encapsulated carbanion was found to be fifty times longer than in solution. The enhanced lifetime allows intermolecular nucleophilic addition chemistry to compete with protonation, effectively, a photo-initiated Grignard-type reaction is observed. In Chapter 6, fluorescence is used as tool to probe both intra- and interzeolite interactions. In the first part, a zeolite-entrapped radical probe was prepared by ship-in-a-bottle synthesis for the investigation of radical percolation in the zeolite matrix. The probe is a molecular dyad containing a persistent free-radical and a quenched fluorophore. When the probe radical couples with a carbon-centered radical, the probe fluorescence is restored and in this way free-radical species in heterogeneous systems can be conveniently examined. In the second section, zeolite particles were irreversibly labeled with a biologically-compatible fluorophore (also by ship-in-a-bottle synthesis). The last part of this thesis deals with a project relating to supramolecular sunscreens. (Abstract shortened by UMI.)

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10

Phillips, Tim. "DNA Binding and Photophysical Studies on Organic Derivatives of Dipyridophenazine." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489744.

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11

Dawson, Alice. "High pressure structural studies of organic molecules." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/12179.

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Procedures for collecting data on a diffractometer equipped with an area detector from samples held within the diamond anvil cell have been developed. The cell construction limits access to reciprocal space and leads to contamination of the diffraction patterns, leading to problems in indexing, data processing and refinement; these effects have been investigated and some strategies for overcoming these are described. Compression studies of the amino acid glycine show the formation of a new polymorph below 8 kbar via a single crystal – single crystal phase transition from the known β-phase of glycine. The formation of this new polymorph can be rationalised on topological grounds by changes in the packing of the molecules to a more favourable body centred cubic based arrangement. γ-glycine was found to undergo a phase transition, characterised using powder diffraction at high pressure. The behaviour is consistent with the formation of δ-glycine. The crystal structure of the amino acid l-alanine is stable to the effects of pressure to at least 70 kbar. The hydrogen-bonding network undergoes significant distortion; this distortion can be explained by the structure adopting a more body centred cubic packing arrangement with increasing pressure. Crystal growth at high pressure from liquid resulted in the formation of new polymorphs of formamide and pyridine. Growth of crystals of the N-methylated analogues of formamide, N-methyl formamide and N,N-dimethyl formamide, did not. The structure of the high pressure polymorph of formamide formed at 4.4 kbar is closely related to the previously known phase. At 10.8 kbar pyridine crystallises in a much simpler structure than that observed at low temperature, matching the structure observed for the perdeuterated molecule. A novel hemi-hydrate of piperidine is observed when grown from liquid at 3.1 kbar.

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12

Guarracino, Paola. "Photophysical processes and molecular ordering in organic materials for third generation photovoltaics studied by EPR spectroscopy." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3424935.

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The world energy consumption is increasing at an average rate of 2.1 % per year, spurred by the economic growth in most of Asian countries, Europe and Canada. The consequent depletion of fossil fuels reservoirs and the reinforced need of environmental sustainability are making the challenge of clean and renewable energy sources one of the most urgent challenges for humankind. Solar power is among the best candidates for the leading role in the energy revolution, being clean, infinite and well distributed over the planet. For this reason, photovoltaic technologies for electricity production are gaining increasing popularity. Although inorganic silicon solar cells dominate the market of photovoltaics, organic and hybrid materials attract considerable interest since their properties like flexibility, light-weight, transparency and low-cost could make the difference in the raising of solar electricity. So far, these materials could not yet outperform conventional silicon, stimulating intensive scientific research on both the development of new materials and the understanding of the photophysical mechanisms governing the photovoltaic behavior of organic/hybrid semiconductors. In this thesis, a series of new organic and hybrid photoactive materials is studied using Electron Paramagnetic Resonance spectroscopy (EPR). This technique, combined with photoexcitation, allows to unambiguously characterize the photoinduced processes involving the formation of paramagnetic states like radicals and triplet states. As shown in the thesis, EPR can also give useful information about molecular ordering in the materials, which is known to be intimately connected with charge transport properties. Conjugated polymers are known for their semiconducting properties and their blends with strong electron accepting fullerene derivatives are among the best performing organic photovoltaic systems. Donor-acceptor alternating copolymers have been introduced to enhance the light-harvesting properties of the blends. Compared to homopolymers, they usually display a lower crystallinity of the deposited films. Thus, XRD techniques are often not suitable to investigate their molecular ordering features. We apply EPR to the analysis of molecular orientational order in the films of two polymers representative of this class, showing that a consistent degree of preferential orientation occurs with two common deposition methods. Fullerene-free materials for polymer solar cells have been recently introduced and overcome some of the drawbacks of fullerene acceptors like the limited absorption and the poor bandgap tunability. In this framework, we study two blends of electron-donor and acceptor polymers to probe their properties with respect to the common fullerene/donor combination, showing that they avoid charge recombination to triplet states which is an active loss mechanism in fullerene-containing blends. Furthermore, the all-polymer films provide a high degree of orientational order and efficient interaction between the donor and acceptor phases that make them promising alternatives to polymer-fullerene blends. A reduced graphene oxide-triphenylamine covalently-linked nanohybrid is studied as potential photosensitizer for TiO2 in dye-sensitized solar cells, able to improve the conductivity and the stability of the system. EPR shows that efficient photoinduced electron transfer from the sensitizer to the semiconductor occurs, paving the way to this new class of photosensitizers. Finally, we investigate the photoactivity of a supramolecular soft-material, forming a gel, composed of small self-assembling donor and acceptor molecules. In this case, EPR allows to verify the efficiency of charge transport across the supramolecular structures, suggesting appealing semiconducting properties of the material. The results of this thesis show the relevance of EPR for unraveling functional and morphological properties of photovoltaic materials and provide a useful characterization of the photophysics of new systems that may be further explored to bring substantial progresses to the field of organic photovoltaics.
Il consumo mondiale di energia ha un tasso medio di crescita del 2.1 % all’anno, trainato dalla crescita economica di molti Paesi asiatici, dell’Europa e del Canada. Il conseguente depauperamento delle risorse di combustibili fossili e il più stringente bisogno di proteggere l’ambiente stanno facendo della sfida delle energie rinnovabili una delle più urgenti sfide che l’umanità deve affrontare. L’energia solare è tra i migliori candidati a svolgere il ruolo di punta nella rivoluzione energetica, essendo una fonte di energia pulita, infinita e ben distribuita nel pianeta. Per questo motivo le tecnologie fotovoltaiche per la produzione di energia elettrica stanno acquistando crescente popolarità. Sebbene le celle solari a base di Silicio dominino il mercato del fotovoltaico, materiali organici e ibridi sono fonte di crescente interesse grazie alle loro peculiari proprietà, come la flessibilità, la leggerezza e la trasparenza, il basso costo, che ci si aspetta possano fare la differenza nell’affermazione del fotovoltaico. Fino ad ora questi materiali non hanno superato il rendimento dei materiali convenzionali a base di Silicio, stimolando la ricerca scientifica verso lo sviluppo di nuovi materiali e lo studio dei meccanismi fotofisici che governano il comportamento fotovoltaico dei semiconduttori organici e ibridi. In questa tesi, una serie di nuovi materiali fotoattivi, organici e ibridi, è stata studiata utilizzando la spettroscopia di Risonanza Paramagnetica Elettronica (EPR). Tale tecnica, combinata con la fotoeccitazione, permette di caratterizzare i processi fotoindotti che portano alla formazione di stati paramagnetici come radicali e stati di tripletto. Come mostrato nella tesi, la tecnica EPR può essere anche utilizzata per ottenere informazioni circa l’ordine molecolare nei materiali, che è noto essere strettamente collegato alle loro proprietà di trasporto di carica. I polimeri coniugati sono noti per le loro proprietà di semiconduttori e le loro miscele con derivati fullereneci - forti electron-accettori - sono tra i sistemi fotovoltaici organici più efficienti. Copolimeri alternanti composti da unità elettron-accettrici e donatrici sono stati introdotti per aumentare l’efficienza di assorbimento dello spettro solare. Rispetto ai classici omopolimeri, questi mostrano solitamente una minore cristallinità dei film depositati. Pertanto, tecniche diffrattometriche si rivelano spesso inadeguate per caratterizzarne l’ordine molecolare. In questa tesi l’EPR viene utilizzato per analizzare l’ordine orientazionale in due polimeri rappresentativi di questa classe, mostrando che un grado consistente di orientazione preferenziale è presente nei film ottenuti con due diverse tecniche di deposizione. Materiali fullerene-free per le celle solari polimeriche sono stati recentemente introdotti per superare alcuni degli svantaggi degli accettori fullerenici, come il limitato assorbimento della luce solare e la difficoltà nel regolare il bandgap e le proprietà elettroniche. In questo conteso, abbiamo studiato due blend costituiti da polimeri elettron-accettori e donatori al fine di investigarne le proprietà e di compararle a quelle dei convenzionali blend di polimeri donatori con derivati fullerenici, dimostrando che essi eliminano la ricombinazione di cariche a formare stati di tripletto, meccanismo noto come fonte di perdita di efficienza nei materiali contenti fullereni. Inoltre, i film polimerici mostrano un elevato grado di ordine orientazionale e un’efficiente interazione tra le fasi di donatore e di accettore che li rendono promettenti alternative ai blend di polimero e fullerene. Un nanoibrido composto da grafene ossido ridotto e molecole di trifenilammina legati covalentemente, è stato studiato come potenziale colorante per la titania in celle solari sensibilizzate a colorante, capace di migliorare la conducibilità e la stabilità del sistema. L’EPR ha mostrato che un efficiente trasferimento elettronico fotoindotto avviene tra l’ibrido e il semiconduttore, aprendo la strada all’applicazione di una nuova classe di coloranti. Infine, la fotoattività di un materiale supramolecolare, un gel composto da piccole molecole di donatore e accettore che autoassemblano, è stata studiata. In questo caso l’EPR ha permesso di verificare un efficiente trasporto di carica attraverso le strutture supramolecolari, suggerendo interessanti proprietà semiconduttive del materiale. I risultati di questa tesi dimostrano la rilevanza dell’EPR per l’indagine su aspetti funzionali e morfologici di materiali fotovoltaici e forniscono una caratterizzazione della fotofisica di nuovi sistemi che potrebbero essere ulteriormente esplorati per apportare progressi sostanziali nel campo del fotovoltaico organico e ibrido.

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13

Demshemino, Innocent Sunday. "Synthesis and Photophysical Studies of Self-Assembled Chromophores." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590713830617676.

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14

Wojtyk, James Taras Ché. "Studies of organic photochromic and photoconductive dye molecules." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0005/NQ42989.pdf.

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15

Graham, D. A. "Microwave spectral studies on selected cyclic molecules." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375454.

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16

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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17

Farshbaf, Sepideh. "Photophysical Studies of Luminescent Supra-Molecules and Their Application in Sensing of Anionic Analytes." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1626352646326308.

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18

Kawai, Nancy T. "Vibrational spectroscopic studies of orientationally-disordered organic cage molecules." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74657.

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The phase behaviour of six orientationally-disordered organic cage molecules, norbornane, norbornylene, norbornadiene, quadricyclane, bicyclooctene, and fluoroadamantane, has been characterized by differential scanning calorimetry, and variable-temperature and -pressure infrared and Raman spectroscopy. All of these compounds undergo one or more solid-solid phase transitions on cooling from disordered phases to ordered, crystalline structures, except for fluoroadamantane, which forms a glass. The phases of all these solids under high pressure have been shown to be the same as those formed at low temperatures.
A method of using pressure dependences of vibrational modes to aid in making spectral assignments is proposed, which proved to be very useful in classifying C-H stretching vibrations and modes which have large contributions from skeletal stretching motions. A semiquantitative analysis of the effect of pressure on different types of stretching vibrations is described.

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19

Ovramenko, Tamara. "STM studies of single organic molecules on silicon carbide." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112315.

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L’interaction de molécules organiques avec les surfaces semiconductrices permet de contrôler les propriétés physiques de ces dernières et ce, soit à travers une modification locale en utilisant des molécules individuelles, soit par la passivation de la surface par une mono-couche complète. Aussi, le contrôle de l’interaction moléculaire nous permet de modifier les propriétés intrinsèques des molécules à travers un découplage électronique partiel ou complet entre les orbitales moléculaires et la surface. Pour atteindre ces objectifs, cette thèse présente l’étude expérimentale de l’adsorption de molécules sur la surface semiconductrice à large gap de 6H-SiC(0001)-3x3. Les expériences ont été réalisées à l’aide d’un microscope à effet tunnel opérant dans les conditions d’Ultra-Haut Vide et de température ambiante (UHV RT-STM). Les résultats ont été comparés à des études théoriques employant des calculs selon la théorie de la fonctionnelle de la densité (DFT). Trois molécules on été étudié durant ce travail de thèse : C60, Caltrope et Trima. Les études STM et DFT montre que les molécules individuelles de C60 sont chimisorbé à la surface de carbure de silicium SiC(0001)-3x3 à travers la formation d’une seule liaison Si-C avec un seul adatome de silicium, contrairement aux autres surfaces semiconductrices où la molécule se chimisorbe en formant plusieurs liaisons. Trois sites d’adsorption par rapport à l’adatome de Si de la maille de surface ont été observés. Pour expliquer les observations STM, les forces de Van der Waals entre la molécule de C60 et les atomes de la surface voisins ont du être pris en compte dans les calculs DFT. Il a été observé aussi que les molécules de C60 forment de petits clusters même à de faibles taux de couverture ce qui indique la présence d’un état précurseur de la molécule et des interactions intermoléculaires non négligeable. La molécule de Caltrope, nouvellement synthétisée, a été étudié aussi bien sur la surface de Silicium que celle de SiC. Le dépôt de cette molécule complexe ne peut être réalisé selon la méthode d’évaporation classique sans induire sa dissociation et a donc nécessité l'emploi de techniques d’évaporation spécifiques. Nos résultats expérimentaux montrent un comportement remarquable: le dépôt de molécule individuelle est induit sur la surface de manière efficace par la pointe du STM démontrant ainsi l’idée d’imprimerie moléculaire. Suite à son adsorption sur la surface de silicium à travers une seule liaison, la molécule de Caltrope se comporte comme un moteur moléculaire activé thermiquement. La troisième molécule a être étudié est la molécule de Trima. Elle a été sélectionnée à cause de sa taille comparable à la distance des ad-atomes de silicium de la surface de SiC. La structure chimique de la molécule qui se termine par un groupement cétone rend possible la fonctionnalisation de la surface. Ceci est révélé par les calculs DFT de la densité de charge. La distribution de charge montre qu’il n’y a pas de partage entre les atomes d’oxygènes de la molécule et les ad-atomes de la surface et donc nous avons un évidence claire pour la formation d’une liaison dative
The interaction of organic molecules with a semiconductor surface enables the physical properties of the surface to be controlled, from a local modification using individual isolated molecules to passivation using a complete monolayer. Controlling the molecular interaction also allows us to modify the intrinsic properties of the molecules by partial or complete electronic decoupling between the molecular orbitals and the surface. To this end, this thesis presents experimental studies of the adsorption of molecules on the wide band gap 6H-SiC(0001)-3×3 substrate. The experiments were performed using Ultra-High Vacuum Room Temperature Scanning Tunneling Microscopy (UHV RT STM) and the results were compared with comprehensive theoretical Density Functional Theory (DFT) calculations. Three different molecules were studied in this thesis: C60, Caltrop and Trima. The STM and DFT studies show that individual C60 fullerene molecules are chemisorbed on the silicon carbide SiC(0001)-3×3 surface through the formation of a single Si-C bond to one silicon adatom, in contrast to multiple bond formation on other semiconducting surfaces. We observed three stable adsorption sites with respect to the Si adatoms of the surface unit cell. To explain the STM observations, Van der Waals forces between the C60 molecule and the neighboring surface atoms had to be included in the DFT calculations. The C60 molecules are also observed to form small clusters even at low coverage indicating the presence of a mobile molecular precursor state and non negligible intermolecular interactions. The second newly designed Caltrop molecule was studied on both the Si and SiC surfaces. Intact adsorption of this complex organic molecule cannot be realized using classical adsorption methods and requires the use of specific evaporation techniques. Our experimental results show remarkable behavior: The STM tip efficiently deposits single molecules one at a time, demonstrating the concept of single molecule printing. After adsorption on the Si surface through one bond, the Caltrop operates as a thermally activated molecular rotor. The third molecule to be studied is the Trima molecule. This molecule was chosen because it is commensurable in size with the surface Si adatom distance. The chemical termination of the molecule with a ketone group enables the successful functionalization of the SiC surface. The Trima molecule provides a rare and clear-cut example of the formation of two dative bonds between the oxygen atoms of the carbonyl groups and the Si adatoms of the SiC surface. This is revealed by the DFT calculations of the charge density. The charge distribution shows that there is no sharing of electrons between the oxygen atoms of the molecule and the surface which is clear evidence for the formation of a dative bond

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20

Chen, Xing. "Theoretical Studies on Magnetic and Photochemical Properties of Organic Molecules." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-52818.

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The present thesis is concerned with the theoretical studies on magnetic and photochemical properties of organic molecules. The ab initio and first principles theories were employed to investigate the vibrational effects on the isotropic hyperfine coupling constant (HFCC) known as the critical parameter in electron paramagnetic resonance spectrum, the theoretical simulations of the vibronically resolved molecular spectra, the photo-induced reaction mechanism of α-santonin and the spin-forbidden reaction of triplet-state dioxygen with cofactor-free enzyme. The theoretical predictions shed light on the interpretation of experimental observations, the understanding of reaction mechanism, and importantly the guideline and perspective in respect of the popularized applications. We focused on the vibrational corrections to the isotropic HFCCs of hydrogen and carbon atoms in organic radicals. The calculations indicate that the vibrational contributions induce or enhance the effect of spin polarization. A set of rules were stated to guide experimentalist and theoretician in identification of the contributions from the molecular vibrations to HFCCs. And the coupling of spin density with vibrational modes in the backbone is significant and provides the insight into the spin density transfer mechanism in organic π radicals. The spectral characters of the intermediates in solid-state photoarrangement of α-santonin were investigated in order to well understand the underlying experimental spectra. The molecular spectra simulated with Franck-Condon principle show that the positions of the absorption and emission bands of photosantonic acid well match with the experimental observations and the absorption spectrum has a vibrationally resolved character. α-Santonin is the first found organic molecule that has the photoreaction activities. The photorearrangement mechanism is theoretically predicted that the low-lying excited state 1(nπ*) undergoing an intersystem crossing process decays to 3(ππ*) state in the Franck-Condon region. A pathway which is favored in the solid-state reaction requires less space and dynamic advantage on the excited-state potential energy surface (PES). And the other pathway is predominant in the weak polar solvent due to the thermodynamical and dynamical preferences. Lumisantonin is a critical intermediate derived from α-santonin photoreaction. The 3(ππ*) state plays a key role in lumisantonin photolysis. The photolytic pathway is in advantage of dynamics and thermodynamics on the triplet-state PES. In contrast, the other reaction pathway is facile for pyrolysis ascribed to a stable intermediate formed on the ground-state PES. The mechanism of the oxidation reaction involving cofactor-free enzyme and triplet-state dioxygen were studied. The theoretical calculations show that the charge-transfer mechanism is not a sole way to make a spin-forbidden oxidation allowed. It is more likely to take place in the reactant consisting of a non-conjugated substrate. The other mechanism involving the surface hopping between the triplet- and singlet-state PESs via a minimum energy crossing point (MECP) without a significant charge migration. The electronic state of MECP exhibits a mixed characteristic of the singlet and triplet states. The enhanced conjugation of the substrate slows down the spin-flip rate, and this step can in fact control the rate of the reaction that a dioxygen attaches to a substrate.
QC 20111220

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21

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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22

Efstathiou, Vasilios Savva. "Infrared spectroscopic studies of organic molecules adsorbed on copper surfaces." Thesis, University of Warwick, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412899.

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23

Maddipatla, Venkata Srirama Narasimha Murthy. "Influence of Confined Media on Photophysical and Photochemical Transformations of Organic Guest Molecules: Water Soluble Supramolecules as Confined Media." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/192.

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For more than 150 years, since the synthesis of urea by Friedrich Wöhler in 1828, molecular chemistry has developed a vast array of highly sophisticated and powerful methods for the construction of more complex molecular structures. Beyond the molecular chemistry based on the covalent bond, there lies the field of supramolecular chemistry, aims to gain control over the intermolecular bond. Supramolecular species are characterized both by the spatial arrangement of their components and by the nature of the intermolecular bonds that hold these components together. They possess well-defined structural, conformational, thermodynamic and kinetic properties. Research has been focused on utilization of such confined spaces to manipulate reaction dynamics, properties of the encapsulated guest molecules. This research presented in this thesis is a consolidated account of photophysical and photochemical reactions carried in water-soluble macrocycles, cavitands and dynamic host systems such as dendrimers and micelles. With the aid of NMR (1D and 2D) spectroscopic techniques, the host-guest complex characterization is executed.

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24

Ball, S. C. "Studies on new mono- and di-lithiated complexes of organic molecules." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596320.

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This thesis describes the syntheses and characterisations of new mono- and di-lithiated complexes of organic molecules of the general formula [(R^x-).xLi⁺].yL. The anion R^x- is either derived from a primary amine or is from a multifunctional organic molecule, containing one or more heteroatoms (usually N or S). The complexes have been prepared either by direct reaction of a simple amine with a metal source (solutions of ⁿBuLi, ^tBuLi, LDA), or via a multi-stage reaction following an established synthetic organic protocol, attempt to isolate the lithiated intermediates at each stage. A variety of solvents, both hydrocarbon (toluene, hexane) and polar solvents (diethylether, THF), were used and all of the metallated complexes contain stoichiometric quantities of Lewis base donors, L (TMEDA, PMDETA, THF, Et₂O). One mono-sodiated complex is also described. The work presented concentrates on the preparation and characterisation of new dilithiated complexes both in the solid state and in solution. The lithiated intermediates in many organic reactions provide a source of such dilithiated molecules. In general deprotonation of an organic acid, followed by insertion of a functional group (CS₂, RCN) into the E-M bond (E=C, N; M=Li, Na) and in some cases further metallation, forms the basis of the reactions described. Chapter 1 provides a general introduction to the area of lithiated organics, with a brief review of X-ray structure analyses and solution studies on such complexes. In Chapter 2 the general experimental methods used to synthesise and characterise these complexes are described. Chapter 3 reports an investigation into an established synthetic protocol for the conversion of β-substituted N-containing heterocycles to their pyrrolo derivatives via metallation and nitrile insertion. Details of complexes 3-C₅H₄NCH=C(Ph)NHC(Ph)=NLi.PMDETA and 2,3-C₅H₄NCH=C(R)NX.xTHF ("problem") are provided where R=Ph or ^tBu and X=Li (L=THF) or X=H. The preparation and characterisation of the mono- and di-lithiated complexes of the related α-substituted pyridine derivatives are also described.

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25

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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26

Matveev, Sergey M. "Photophysics and photochemistry of diiodomethane and hexabromoiridate - paradigm molecules for organic and inorganic chemistry - studied with sub-50-fs broadband pump-probe spectroscopy." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1467909513.

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27

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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28

Hathway, Timothy Lee. "Titanium dioxide photocatalysis studies of the degradation of organic molecules and characterization of photocatalysts using mechanistic organic chemistry /." [Ames, Iowa : Iowa State University], 2009. 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:3369929.

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29

Aratikatla, E. K. "Design and synthesis of artemisinin-dipeptidyl vinyl phosphonate hybrid molecules as novel antimalarial agents: synthesis of biologically active molecules and studies directed towards bioactives from vernonia arborea." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2018. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4592.

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30

Luschtinetz, Regina. "Theoretical studies towards a ferroelectric organic field-effect transistor based on functional thiophene molecules." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-102735.

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Thin-film organic field effect transistors (OFETs) have attracted growing interest in recent years due to their promising electrical, optical and mechanical properties. Especially, oligothiophenes and their derivates are candidates with good prospects for application as the organic semiconducting material in such devices. They possess an extended, polarisable aromatic π-electron system that promotes a high structural arrangement of the molecules. The charge transport in the organic film is realised in the direction perpendicular to the plane of the thiophene rings via a hopping transport mechanism. Thus, a good π-π-overlap and a consequent stacking of the thiophene molecules in the film perpendicular to the gate substrate is essential to achieve excellent electric properties such as high charge carrier mobilities and low resistive losses. The highly polarisable thiophene-based molecules are also very attractive materials that are potentially applicable as the field-sensitive organic semiconducting component of a ferroelectric OFET device. In such a device, the dielectric gate element of a conventional OFET setup is substituted by a ferroelectric substrate. The electric field that is induced by the polarisation of the ferroelectric material serves as gate field and controlls the charge injection and charge density inside the device. In this thesis, thiophene-based molecules are investigated in detail with respect to their application as field-sensitive organic semiconducting component in a ferroelectric OFET device employing quantum-chemical ab initio and DFT-based methods. We demonstrate that the phosphonic acids can bind the organic molecules to the dielectric or ferroelectric material and well-anchored, robust self-assembled monolayers are formed. Furthermore, special focus is put on the influence of the intermolecular interactions among the organic molecules on the technologically relevant structural and electronic properties. It is found that the CN···HC hydrogen bond link the molecules into extended ribbons, but the π-π-stacking-stacking interaction is the main driving force in the self-assembly of the molecules. We also establish in detail the influence of the electric field on the phosphonic acid anchoring molecule and some quarterthiophene derivates. For the latter, the strongest field-sensitivity is obtained for an external electric field aligned parallel to the extension of the thiophene framework. Hence, they are suitable to act as the field-sensitive organic components in devices that take advantage of a band-gap engineering. Moreover, the present results emphasise the importance of the adsorption morphology of the molecules in the film in a π-stacked fashion with their longitudinal axis oriented parallel to the (orthonormal) electric field induced by the ferroelectric substrate.

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31

Halfen, DeWayne Terrence. "Studies in Laboratory Spectroscopy and Radio Astronomy: From Simple Hydrides to Complex Organic Molecules." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195962.

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There are two main objectives for this thesis. First, laboratory rotational spectra of metal-containing molecules were measured using the millimeter-wave spectrometers of the Ziurys group. Second, radio astronomical observations were performed on a number of the molecules measured in the laboratory, along with several organic species. The laboratory work is essential to the discovery of new molecules in the interstellar medium, and the understanding of the chemical composition of the universe. Identification of these species can only occur after their pure rotational spectra have been measured. Therefore, an investigation of the rotational spectra of several classes of molecules was performed including metal-bearing hydrides, chlorides, carbon-containing species, and molecular ions. The experimental measurements were aided by necessary improvements in the operation of the spectrometers. Many of these species had not been observed by any spectroscopic technique, including CaC, CuCH₃, FeCO⁺ and VCl⁺. Several of these molecules exhibited unusual interactions that complicated the analysis of their spectra, such as VCl, TiCl⁺, VCl⁺, and FeCO⁺. Synthesis of these species required exotic production techniques, including the use of Broida ovens and AC and DC discharges. Astronomical observations of several of the molecules studied in the laboratory were conducted, and upper limits to the abundances obtained. Additional searches for more of the species studied are planned. A region in the Galactic center with a complex chemical composition called Sgr B2(N) was recognized through observations of N₂O. Several organic species were then searched for in this source. The detection of the simple sugar glycolaldehyde was confirmed by observing all of the favorable transitions of this molecule in Sgr B2(N). A standard set of criteria for identifying complex organic molecules was drawn up as a result of this study. This investigation led to an attempt to confirm a larger sugar, dihydroxyacetone. Unfortunately the detection of this species was proven false, and a limit could be placed on the chemical complexity of this source.

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32

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 MEDIA

The 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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33

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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34

Zhou, Juefei. "Using sum rules to guide experiential and theoretical studies of the intrinsic nonlinear-optical susceptibility of organic molecules." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/j_zhou_113007.pdf.

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35

Furukawa, Shinya. "Studies on Catalytic Aerobic Oxidation of Organic Molecules: Development in Activation of Molecular Oxygen and Substrates." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157538.

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36

Mukherjee, Sumit. "Studies on thermochemical properties of small organic molecules by mass spectrometry in relation to computational chemistry." Scholarly Commons, 2010. https://scholarlycommons.pacific.edu/uop_etds/2424.

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Melamine and cyanuric acid are widely used in industry and in scientific research. The mixture of melamine and cyanuric acid can form a hydrogen-bonded network structure which has been used as a surface template in supramolecular chemistry. In this work, the thermochemical properties of melamine and cyanuric acid were characterized using mass spectrometry measurements and computational studies. The proton affinity and the gas-phase acidity were determined with the application of the extended Cooks kinetic method. A triple-quadrupole mass spectrometer equipped with an electrospray source was employed for this study. For melamine, the proton affinity, the gas-phase basicity, and the protonation entropy were determined to be 226.2 ± 2.0 kcal/mol, 218.4 ± 2.0 kcal/mol and 26.2 ± 2.0 cal/mol K, respectively. For cyanuric acid, the deprotonation enthalpy, the gas-phase acidity, and the deprotonation entropy were determined to be 330.7 ± 2.0 kcal/mol, 322.9 ± 2.0 kcal/mol and 26.1 ± 2.0 cal/mol K, respectively. The geometries and energetics of melamine, cyanuric acid, and related molecules/ions were calculated at the B3LYP/6-31+G(d) level of theory. The theoretical proton affinity and deprotonation enthalpy were calculated using the corresponding isodesmic proton transfer reactions. The computationally predicted proton affinity of melamine (225.9 kcal/mol) and gas-phase deprotonation enthalpy of cyanuric acid (328.4 kcal/mol) were in good agreement with the experimental results. Melamine is best represented as the imide-like triazine-triamine form and the triazine nitrogen is more basic than the amino group nitrogen. Cyanuric acid is best represented as the keto-like tautomer and the N-H group is the most likely proton donor. Cyclohexane-based molecular switches have been of great interest in recent years. This work focused on the investigations of the thermochemical properties related to the switching process. A group of cyclohexane-based model compounds were selected for this study. The model compounds included trans -2-aminocyclohexanol, trans -4-aminocyclohexanol and trans -2-dimethylaminocyclohexanol. The proton affinities of the compounds were determined using the extended Cooks kinetic method. The values obtained were 238.5 ± 2.0 kcal/mol ( trans -2-dimethylaminocyclohexanol), 225.5 ± 2.0 kcal/mol ( trans -2-aminocyclohexanol) and 220.4 ± 2.0 kcal/mol ( trans -4-aminocyclohexanol). Various molecular structures related to the model compounds and the switching molecules were calculated at the B3LYP/6-31+G(d) level of theory. The theoretical proton affinities of all the molecules investigated were also calculated at the same level of theory using corresponding isodesmic reactions. The results show that the proton affinities decrease as the relative positions of amino and alcohol groups change from ortho to meta to para . The stronger proton affinity of the ortho isomer may be due to the efficient intramolecular hydrogen bonding in the protonated form. The proton affinity of trans -2-dimethylaminocyclohexanol is stronger than that of trans -2-aminocyclohexanol by about 13 kcal/mol. Substitution of hydrogen atoms by methyl groups at nitrogen promotes the intramolecular hydrogen bonding between the amino group and the hydroxyl group upon protonation. This, in turn, may enhance the proton affinity of methylated molecule. Computational studies also show interesting trends for stabilities and proton affinities of the different structures. These data may be useful as a guide for designing efficient conformational switches.

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Weerasinghe, Krishanthi Chandima. "DENSITY FUNCTIONAL THEORY STUDIES OF PHOTOINDUCED ELECTRON EXCITATION AND TRANSFER OF ORGANIC DYES FOR PHOTODYNAMIC THERAPY, SOLAR CELLS, AND FLUORESCENCE SENSOR APPLICATIONS." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1234.

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The main aim of work presented here is to understand photophysical processes of organic dyes and to design better organic molecules/systems which can be applied in many applications such as solar cells, photodynamic therapy, and fluorescence sensors. Developments of novel multichromophore organic materials for the above mentioned applications were made using computational tools. A brief description of the history of computational chemistry was given based on the photochemistry of organic dyes in the introductory chapters and also the importance of basis sets and functionals was discussed in order to produce accurate computational results. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were performed to understand the photophysical processes in the porphyrin-perylene bisimide (HTPP-PDI) dyad that exhibited long-lived triplet states. The DFT results show that breaking the rigidity of PDI in HTPP-PDI was responsible for the generation of long-lived triplet states. Furthermore, six porphyrin derivatives were designed by introducing a 4,4’-dicarboxybutadienyl functional group to the porphyrin moiety and studied to investigate the substituent effects on the non-coplanarity, molecular orbitals, and excitation wavelength of the porphyrin donor. Five of the six proposed porphyrin derivatives are promising donors in the HTPP-PDI dyad to replace HTPP for its potential use in photodynamic therapy. Six donor- accepter(s) systems were designed for their potential application in solar cells. Four D-A1-A2 architectural triads, MTPA-TRC-AEAQ, MTPA-TRC-HTPP, MTPA-TRC-PDI, and MTPA-TRC-PBI were designed. The cascade electronic energy levels were obtained and experimentally observed, which lead to sequential electron transfers from 1MTPA* to TRC and then to AEAQ (HTPP/PDI/PBI) module as well as a hole transfer from 1AEAQ*(1HTPP*/1PDI*/1PBI*) to MTPA module. Therefore, all the D-A1-A2 systems we have designed are ambipolar. Interestingly, the lifetime of charge separated states of the newly designed MTPA*+-TRC-AEAQ*- was elongated to 650 ns, an eightfold of that of the donor-acceptor MTPA-TRC parent molecule (80 ns). However, different charge separated state lifetimes were obtained for MTPA*+-TRC-PDI*-(22ns) and MTPA*+-TRC-PBI*-(75ns). The photophysical results suggested that the charge separated state may decay to the triplet state when the charge separated state exhibits a higher energy level than the triplet state. Further, the photovoltaic tests indicated potential applications of MTPA-TRC-AEAQ in solar cells. DFT and TDDFT calculations were performed together with experimental studies to explore the nature of fluorescence enhancement in the anthracene-based sensor after the addition of Zn2+. A 23-fold fluorescence emission was quenched via non-radiative decay pathway in the absence of Zn2+. However, when the Zn2+ chelated to the sensor fluorescence intensity was increased remarkably. A 32-fold fluorescence increase was overserved and calculation results suggested this could be due to the inhibition of the electron-transfer pathway and enhanced rigidity of sensor-Zn2+ complex. The response selectivity of Zn2+ over Ca2+, Mg2+, Cu2+, and Hg2+ ions was also studied using DFT calculations and it was found that Zn2+ has a strong binding affinity to the sensor, which could be a potential application in the detection of Zn2+.

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38

Vetromile, Carissa Marie. "Probing Molecules in Confined Space." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3393.

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Despite the plethora of information regarding cellular crowding and its importance on modulating protein function the effects of confinement on biological molecules are often overlooked when investigating their physiological function. Recently however, the encapsulation of biomolecules in solid state matrices (NafionTM, sol-gels, zirconium phosphate,etc.) has increased in importance as a method for examining protein conformation and dynamics in confined space as well as novel applications in biotechnology. Biotechnological applications include, but are not limited to, bioremediation, biosensors, biocatalysts, etc. In order to better utilize solid state materials as substrates for biological molecules an understanding of the effects of encapsulation on the detailed dynamics associated with physiological function is required as well as a complete characterization of the physical properties associated with the space in which the biological molecule is to be confined. The focus of this research is to probe the effects of confinement on the thermodynamics of ligand photo-release/rebinding to the prototypical heme protein, myoglobin, encapsulated within sol-gel glasses utilizing photoacoustic calorimetry (PAC) and photothermal beam deflection (PBD). Optical spectroscopies (including optical absorption and fluorescence) have also been employed to characterize the molecular environments of materials including Zr-phosphate and metal organic polyhedral (MOPs), thought to be good candidates for novel bio-hybrid materials. The assembly mechanisms associated with MOPs were also examined in order to develop a foundation through which new, bio-compatible MOPs can be designed. Overall the results presented here represent a technological breakthrough in the application of fast calorimetry to the study of proteins in confined space. This will allow for the first time the acquisition of detailed thermodynamic maps associated with the well-choreographed biomolecular dynamics in confined environments.

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Lai, Lai Fan. "Synthesis and characterization of new functional molecules and application studies in dye-sensitized and organic solar cells." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/81.

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This thesis describes the synthesis and characterization of a series of photosensitizers, transition metal-containing polymers and small organic molecules for dye-sensitized solar cells and organic solar cells. To begin with, a brief overview on the background of dye-sensitized solar cells (DSSCs) and organic solar cells was presented in Chapter 1. In Chapter 2, a series of novel donor-acceptor-π-acceptor bithiazole-based and fluorenone-based organic dyes for dye-sensitized solar cells were successfully synthesized and fully characterized. We discovered that the performance of the photovoltaic devices depends significantly on the nature and strength of the electron-donating end group along the conjugated main. Some of the materials have been found to show higher power conversion efficiency of 4.71% (Voc = 565 mV, Jsc = 11.71 mA cm–2, FF = 0.71) under AM 1.5 irradiation (100 mW cm–2). In Chapter 3, ten novel donor-donor-π-acceptor organic dyes for dye-sensitized solar cells have been synthesized and applied for the fabrication of DSSCs, including six dibenzothiophene-based photosensitizers and carbazole-based photosensitizers. All the dyes have efficient charge injection from the excited sensitizer molecule to TiO2 conduction band and can provide ample driving force for efficient dye regeneration best overall light to electricity conversion efficiency of 5.28% (Voc = 0.70 V, Jsc = 11.06 mA cm–2, FF = 0.68) under AM 1.5 irradiation, which reached 73% with respect to that of an N719-based device fabricated under similar fabrication conditions. Besides, nine novel di-anchoring organic sensitizers employing two different electron-donating cores, which are the fluorene and carbazole units, and two symmetrical anchoring cyanoacrylic acid (acceptor) termini have been synthesized and studied for their applications in DSSCs in Chapter 4. In Chapter 5, four new platinum polyyne polymers were prepared via the Sonogashira-type dehydrohalogenation reaction between the ethynyl precursor and trans-Pt(PBu3)2Cl2. All of the polymers are air-stable and well characterized by different spectroscopic methods and photophysical measurements. Their photovoltaic behaviors were fully investigated. Their model compounds were also prepared and studied. In Chapter 6, a series of new organic small molecules were designed and synthesized comprising head-to-head coupled heylthiophene, dithienosilole and dithienogermole units. They exhibited broad absorption peaks with favorable spectral overlap with the solar spectrum. These seven small molecules have been applied to presented. Among these molecules, the highest PCE of 4.93% was achieved with a Voc = 0.79 V, Jsc = 1.22 mA cm-2 and FF = 0.51 under illumination of an AM 1.5 solar cell simulator. Finally, Chapters 7 and 8 present the concluding remarks and the experimental details of the work described in Chapters 2−6

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40

Wagholikar, S. G. "Studies on carbon-carbon bond formation reactions of organic molecules over zeolites and other molecular sieve catalysts." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2417.

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41

Handt, Jan. "Ab-initio molecular dynamics studies of laser- and collision-induced processes in multielectron diatomics, organic molecules and fullerenes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-62279.

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This work presents applications of an ab-initio molecular dynamics method, the so-called nonadiabatic quantum molecular dynamics (NA-QMD), for various molecular systems with many electronic and nuclear degrees of freedom. Thereby, the nuclei will be treated classically and the electrons with time-dependent density functional theory (TD-DFT) in basis expansion. Depending on the actual system and physical process, well suited basis sets for the Kohn-Sham orbitals has to be chosen. For the ionization process a novel absorber acting in the energy space as well as additional basis functions will be used depending on the laser frequency. In the first part of the applications, a large variety of different laser-induced molecular processes will be investigated. This concerns, the orientation dependence of the ionization of multielectronic diatomics (N2, O2), the isomerization of organic molecules (N2H2) and the giant excitation of the breathing mode in fullerenes (C60). In the second part, fullerene-fullerene collisions are investigated, for the first time in the whole range of relevant impact velocities concerning the vibrational and electronic energy transfer (\"stopping~power\"). For low energetic (adiabatic) collisions, it is surprisingly found, that a two-dimensional, phenomenological collision model can reproduce (even quantitatively) the basic features of fusion and scattering observed in the fully microscopic calculations as well as in the experiment. For high energetic (nonadiabatic) collisions, the electronic and vibrational excitation regimes are predicted, leading to multifragmentation up to complete atomization.

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42

Wang, Yongfeng. "SYNTHESIS AND STRUCTURE-PROPERTY STUDIES OF ORGANIC MATERIALS CONTAINING FLUORINATED AND NON-FLUORINATED # SYSTEMS (SMALL MOLECULES AND POLYMERS)." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/593.

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Loline alkaloids (LA) are secondary metabolites produced by Epichloandamp;euml; (anamorph, Neotyphodium) grass endophytes. They are toxic and deterrent to a broad range of herbivorous insects but not to livestock. This protective bioactivity has spurred considerable research into the LA biosynthetic pathway. LOL, the gene cluster containing nine genes, is required for LA biosynthesis. The regulation of LOL genes during LA production in culture and in symbio is of interest. In this study, coordinate regulation between LOL gene expression and LA production level was investigated in both MM culture and symbiota. Results showed that expression of LOL genes in N. uncinatum MM culture were tightly correlated with each other (p andamp;lt; 0.0005), and all presented a significant temporal quadratic pattern during LA production. Gene expression started before LA were detectable, and increased while LA accumulated. The highest gene expression level was reached before the highest amounts of LA were detected, and gene expression level declined to a very low level after amounts of LA plateaued. Observations suggested that the hierarchical clusters based on the correlation coefficient could help to predict the roles of LOL genes in the LA pathway. In symbiota, coordinate coregulation of LOL gene expression with LA was found in E. festucae-meadow fescue inflorescences and stromata, whereby lower LOL gene expression corresponded with the lower LA level in stromata. In N. uncinatum (or N. siegelii)-meadow fescue vegetative tissues, dramatically higher LA levels were found in younger leaf tissue than in older leaf tissue, yet no evidence was found to relate this difference to LOL gene expression differences. Instead, substrate availability may regulate the LA level. In particular, asparagine was more than 10-fold higher in young leaf tissue than in old tissue, although proline was significantly lower in young tissue. Therefore, different regulatory mechanisms underlie LOL gene expression and LA production in different circumstances. The GUS activity of Pro-lolC2-GUS and Pro-lolA2-GUS in Neotyphodium species was almost undetectable in culture, though the activity could be detected in symbiota. The mRNA of GUS did not exhibit the same pattern as lolC2 or lolA2 in culture during LA production time course. A Pro-lolC2-cre transgene was expressed in complex medium, in which lolC2 mRNA was not detectable. These results suggest that proper regulation of LOL genes in culture or symbiota is dependent on the LOL cluster.

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43

Bruin, Richard Paul. "Development of a grid computing infrastructure to support combinatorial simulation studies of pollutant organic molecules on mineral surfaces." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444783.

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44

Hegde, V. R. "Development of homogeneous and heterogeneous transition metal based catalytic organic synthetic methodologies and synthetic studies towards bioactive molecules." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1996. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2910.

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45

Ramalingam, S. "Synthetic studies towards bioactive molecules using asymmetric dihydroxylation and organic transformation using yttria- zirconia and other heterogeneous catalyst." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2467.

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46

Acharya, Rajendra. "Synthesis, Characterization and Photophysical Studies of Porphyrin and N-Confused Porphyrin Derivatives and Self-assembled Nano-Morphologies." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376061548.

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47

Tikhomirova, Anastasiia. "Studies of Photoinduced DNA Damage by Phenanthrene Dihydrodioxin and Light-driven Electron Delocalization in Pyridinium Molecules." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1561918589357022.

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48

Jin, Jiamei. "Fundamental studies on the adsorption and oxidation of small organic molecules at the Ru(0001) electrode under various conditions." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440568.

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49

Halldin, Stenlid Joakim. "Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion." Doctoral thesis, KTH, Tillämpad fysikalisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213028.

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The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden. In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface. An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces. Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology.
Den kemiska bindningen – en hörnsten inom naturvetenskapen och oumbärlig för allt liv – är det centrala temat i den här avhandlingen. Både grundläggande och tillämpade aspekter behandlas. Detta inkluderar utvecklingen av nya beräkningsmetoder för förståelse och karaktärisering av kemiska interaktioner. Dessutom behandlas korrosion av kopparbaserade material. Det sistnämnda är motiverat av förslaget att använda koppar som inkapslingsmaterial för hanteringen av kärnavfall i Sverige. Kvantkemiska beräkningsmetoder enligt state-of-the-art har använts för att studera kemi på atomnivå, detta i nära sammabete med experimentella grupper. Initialt studerades oxidation av kopparnanopartiklar under syrgasfria och vattenrika förhållanden. Detta för att bättre kartlägga koppar-vattensystemets termodynamik. Av samma orsak detaljstuderades även gränsskiktet mellan vatten och kuprit med fokus på dess kemiska sammansättning och reaktivitet. Resultaten har jämförts med metanols och vätesulfids kemiska beteende på ytan av kuprit. En övergripande målsättningen under arbetet med att utveckla nya beräkningsbaserade analysverktyg för kemiska bindningar har varit att överbrygga gapet mellan molekylär- och materialkemi. Därför presenteras teoretiska aspekter samt tillämpningar från både ett molekylärt samt ett fast-fas perspektiv. En ny deskriptor för karaktärisering av föreningars lokala elektrofilicitet har introducerats – den lokala elektronadditionsenergin. Tillsammans med den elektrostatiska potentialen uppvisar den nya deskriptorn förmåga att förutsäga samt förklara regioselektivitet och trender för molekylära reaktioner, och för interaktioner på metal- och oxidbaserade nanopartiklar och ytor. En detaljerad förståelse av kemiska processer på atomnivå är en nödvändighet för ett effektivt utvecklande av kemivetenskapen. Vi förutspår därför att resultaten från den här avhandlingen kommer att få omfattande användning inom områden som heterogen katalys, läkemedelsdesign och nanoteknologi.

QC 20170829

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Lau, Wai Sum. "Synthesis, characterization and application studies of cyanostilbene-based molecular materials with aggregation-induced emission (AIE) characteristics." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/70.

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The molecular design, synthesis, spectroscopic and photophysical characterization of a series of cyanostilbene-based compounds are studied in this thesis. The thermal, electrochemical and aggregation induced emission (AIE) properties of these cyanostilbene-based compounds, as well as their application in organic lighting-emitting diodes, live cell imaging, chemical vapor sensor were investigated. Chapter 1 gives a brief introduction on the aggregation-caused quenching (ACQ) behavior of the conventional organic luminogens and the discovery and proposed mechanism of AIE phenomenon. Furthermore, some examples and the applications of these AIE compounds will be discussed. In Chapter 2, triphenylamine- and carbazole-containing cyanostilbene-based derivatives are presented. From the examination of the emission profile, they are all AIE-active through comparison of the photoluminescence intensity in dissolved and in aggregated states. Additionally, the calculation of the enhancement ratio (I/I0 – 1) of each fluorophore was performed in order to quantify its AIE effect. One of our cyanostilbene-based luminogens has achieved an enhancement ratio with a value of 1128. This cyanostilbene-based luminogens has also shown good performance in OLED investigation. In addition to the OLEDs application, the selected cyanostilbene-based luminogens with solid-state emission, cell-permeability and reversible switch-on/off capability have illustrated the positive result in live-cell imaging and chemical vapor sensing. Conjugated polymer with high molecular weight is the superior option by overcoming the weaknesses of low-molecular-weight luminogens with excellent thin-film form ability and comparatively simple and inexpensive fabrication processes. The design and synthesis of the cyanostilbene-based polymeric chromophores are described in Chapter 3. The polymerization of the AIE-active diacetylene ligands by connection of trans-[Pt(PBu3)2] unit at both ends has successfully retained their AIE behavior. In contrast, the ACQ problem has occurred on the polymers with organic spacers and the AIE-active ligands. From the DFT calculation on the Pt polymers and the blue shift of emission spectra in high water content suggested that the AIE phenomenon of Pt polymers is probably originated from the elimination of the non-radiative intramolecular charge transfer (ICT) process. Owing to the high demand in red-emitting materials in the applications of electroluminescent devices, fluorescent sensing and bio-imaging, effort has been made to design a system with the new chromophores with donor (D) – acceptor (A) system and thus to synthesize phenothiazine (D)-containing cyanostilbene (A)-based derivatives which are depicted in Chapter 4. Consistent with the conventional AIE-active luminogens with a successively climb of photoluminescence intensities in response to the increase of water proportion, phenothiazine-containing cyanostilbene-based derivatives has exhibited a V-shape fashion of emission intensity. It suggests that the emission of chromophores started to be quenched due to the increase of solvent polarity, overriding that of the molecular aggregation when a “small” volume of water is being introduced. While aggregate formation was dominant from the addition of a “large” amount of poor solvent, less polar local environment was created which suppressed the non-radiative transition to the ICT state and intensified the emission efficiency. Phenothiazine (D) – cyanostilbene (A) system has created a series of red-emitting chromophores with great tunability for the sake of achieving the desired emission color and better emission efficiency. To functionalize these AIE-active cyanostilbene-based chromophores, pyridine group was attached to the compounds to take the advantage of its metal-chelating capability, which is discussed in Chapter 5. The AIE features of cyanostilbene-based compounds can be preserved after the introduction of the pyridyl unit. Even it possessed a weak photoluminescence in its dilute solution which suggest that the high electron delocalization within the molecule has rigidified the structure to some extent, it is transformed to a highly emissive state with a high proportion of water. The exclusive variation of emission behavior with obvious bathochromic shift and boost of emission spectrum in the presence of cadmium-(II) ion has demonstrated its potential metal ion sensing ability. Chapter 6 and 7 present the concluding remarks and the experimental data of the compounds of Chapter 2 to 5, respectively.

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