Дисертації з теми "Excited State Proton Transfer (ESPT)"
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Weragoda, Geethika K. "Excited state intramolecular proton transfer (ESIPT) and trans-cis isomerization on the triplet excited states." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439296134.
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2
Salvitti, Michael Anthony. "N-methyl-6-hydroxyquinolinium : an investigation into the spectroscopy and applications of excited-state proton transfer /." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24665.
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Vérité, Pauline. "Modelling of excited state proton transfer in in fluorescent dyes." Thesis, Nantes, 2020. http://archive.bu.univ-nantes.fr/pollux/show.action?id=ebc433d0-1c13-4ae5-a308-9fafee57c623.
Повний текст джерелаАнотація:
Cette thèse est dédiée à l'exploration des surfaces d'énergie potentielle des états électroniques excités de colorants "ESIPT" (Excited-State Intramolecular Proton Transfer) à l'aide d'approches de chimie quantique. Le phénomène ESIPT s’observe typiquement dans des molécules présentant une liaison hydrogène intramoléculaire forte. Le changement de géométrie provoqué par ce transfert permet d’obtenir une grande différence entre l’absorption et l’émission (grand déplacement de Stokes), ouvrant la voie à de multiples applications. Le but de cette thèse est d'identifier les substituants les plus adéquats pour obtenir des signatures d’émission spécifiques, en étroite collaboration avec le groupe expérimental de G. Ulrich à Strasbourg. Pour ce faire, la théorie fonctionnelle de la densité dépendante du temps (TD-DFT) ainsi que des approches post-Hartree-Fock [ADC(2) et CC2] ont été utilisées pour modéliser les propriétés de nombreux colorants. Une attention particulière a été portée aux effets de l’environnement avec l’utilisation d’approches de continuum sous leurs formes de réponse linéaire (LR) et de réponse linéaire corrigée (cLR). Les travaux réalisés lors cette thèse ont permis : i) d’évaluer l'impact des auxochromes (accepteurs et donneurs d'électrons) sur la stabilité des tautomères à l’état excité ; ii) de quantifier les états de transition entre deux ou trois formes tautomériques ; iii) de déterminer les propriétés spectrales des isomères ; et iv) d’identifier les espèces émissives dans le cas d’un système acidochrome complexeThis thesis is dedicated to the exploration of potential energy surfaces of excited electronic states of "ESIPT" (Excited-State Intramolecular Proton Transfer) dyes, using quantum chemistry approaches. The ESIPT phenomenon is typically found in molecules possessing a strong intramolecular hydrogen bond. The change in geometry induced by the ESIPT yields a large difference between the absorption and emission wavelengths (large Stokes’ shift), paving the way to multiple applications. The aim of this thesis is to identify the most suitable auxochromes to obtain specific emissive signatures, in close collaboration with the experimental group of G. Ulrich (Strasbourg). To this end, Time-Dependent Density Functional Theory (TD-DFT) as well as post-Hartree- Fock approaches [ADC(2) and CC2] have been used to model the properties of many dyes. A specific attention was paid to accurately model the environmental effects by using continuum approaches in their linear response (LR) and corrected linear response (cLR) forms. The work carried out during this thesis allowed: i) to evaluate the impact of auxochromes (acceptors and electron donors) on the stability of the tautomers in the excited state; ii) to quantify the transition states between two or three tautomeric forms; iii) to determine the spectral properties of all relevant isomers; and iv) to identify the emissive species in a complex acidochromic system
4
Le, Gourrierec Denis. "Excited state intramolecular proton transfer (ESIPT) to nitrogen in heterocyclic compounds." Thesis, University of Central Lancashire, 1996. http://clok.uclan.ac.uk/21906/.
Повний текст джерелаАнотація:
Excited state intramolecular proton transfer (ESIPT) reactions have aroused considerable interest in the last 10-15 years. The ESIPT reaction is normally extremely rapid and yields excited species of considerably lower energy than the initial Franck-Condon excited state. ESIPT has therefore been used for the rapid dissipation of energy (e. g. for polymer protection against UV degradation) and to produce fluorophores with large Stokes shifts. Approximately half of the compounds studied to date involve ESIPT to nitrogen but there has been no real attempt at a coherent study of ESIPT to nitrogen. In this work we have tried to remedy this deficiency by studying a range of compounds of increasing complexity in order to characterise ESIPT and subsequent reactions and to evaluate how these properties vary with molecular structure. The molecules selected for this studyf all into two categories: - The azole group includes the 2-(2'-hydroxyphenyl)-oxazole (HPO) and -thiazole (HPT) whose study complements their well known benzo counterparts (HPBT and HPBO) and the related imidazoles. - The compounds of the pyridine group are related to the basic structure of 2-(2'-hydroxyphenyl)-pyridine (HPP). Structural variations involve benzo fusion (quinolines) and addition of a 3,3' bridge. A complementary compound is the well studied 2,2'-bipyridyl-3,3'-diol (BP(OH)2) which undergoes double proton transfer. Whenever possible, the methoxy counterparts were prepared in order to study the photochemistry of these compounds when ESIPT is not possible. The absorption and fluorescence properties of these systems were studied as a function of solvent, temperature and pH conditions. Lifetimes, quantum yields and pKa data were determined under these various conditions and semi-empirical quantum chemical calculations were performed on each system.
5
Chen, Weihua. "Chemical Sensors Based on Fluorescence Turn-On Mechanism by Using Excited State Intramolecular Proton Transfer." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1334772708.
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Dahal, Dipendra Dahal. "SYNTHESIS AND CHARACTERIZATION OF NOVEL EXCITED STATE INTRAMOLECULAR PROTON TRANSFER (ESIPT) CYANINE DYES WITH NEAR INFRARED (NIR) EMISSION FOR BIOLOGICAL APPLICATIONS." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1567644552737644.
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McDonald, Lucas J. "Synthesis and Characterization of Novel Flavonoid-Based Fluorescent Sensors and other Sensors with Excited State Intramolecular Proton Transfer for Biological Applications." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1524658238472646.
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Zhang, Wanying. "Comprehensive Study on Fluorescent ESIPT Liquid Crystal Materials and the Potential for Optoelectronic Applications." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263621.
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Linares-Samaniego, Sandra I. "Excited state proton transfer in microheterogeneous conditions." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/27263.
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Potter, Charles Alan Stuart. "Excited state proton transfer in 2-substituted benzothiazoles." Thesis, University of Central Lancashire, 1993. http://clok.uclan.ac.uk/19742/.
Повний текст джерелаАнотація:
The photophysics of 2-(2'-hydroxyphenyl)benzothiazole (HBT) and related compounds has been studied as a function of solvent, pH or H 0 and temperature. Measurements of absorption and fluorescence spectra and fluorescence decay profiles under these various conditions have been combined with theoretical calculations to arrive at an understanding of the excited state behaviour of HBT and derivatives. An investigation has been made into the protonation and deprotonation of 2-phenylbenzothiazole, 2-(2'-methoxyphenyl)benzothiazole), HBT and derivatives of HBT with bromine, chlorine, hydroxy, methoxy, methyl and nitro substituents in the 2-phenyl ring. Absorption and fluorescence spectra have been combined with Forster cycle calculations to yield pKa, pKb, pKa* and pKb* values for the various compounds. The results have been compared with those for the corresponding phenols and many similarities noted. The overlap of the pK a* and pKb* values for HBT and derivatives has been noted. This has explained the occurrence of excited state intramolecular proton transfer (ESIPT) in these compounds. A study of the photophysics of HBT in non-polar and alcoholic mixtures for temperatures in the range 96-298K has been made using the Berlin synchrotron source, BESSY. In all solvents a rise in both fluorescence quantum yield and lifetime is observed as the temperature is decreased. It is proposed that a viscosity dependent non-radiative process leading to a nonemissive, twisted excited state accounts for these observations. Application of quantum chemical calculations to the system appears to confirm this interpretation. The fluorescence kinetics of HBT have been studied as a function of alkaline pH. Combination of the lifetime data with quantum yields and pK a* values have allowed calculation of all the rate constants in the neutral c → anion equilibrium for HBT. Similar measurements have been undertaken for substituted HBTs and for HBT at high acidities, but the data obtained has been less easy to interpret.
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Marks, David Roland Azoulai. "Femtosecond studies of excited-state proton transfer reactions in solutions." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/82013.
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Spry, David Ben. "Ultrafast excited state proton transfer in the condensed phase and nanoconfinement /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Maza, William Antonio. "Reaction Enthalpy and Volume Profiles for Excited State Reactions Involving Electron Transfer and Proton-Coupled Electron Transfer." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4539.
Повний текст джерелаАнотація:
Electron transfer, ET, and proton-coupled electron transfer, PCET, reactions are central to biological reactions involving catalysis, energy conversion and energy storage. The movement of electrons and protons in either a sequential or concerted manner are coupled in a series of elementary reaction steps in respiration and photosynthesis to harvest and convert energy consumed in foodstuffs or by absorption of light into high energy chemi-cal bonds in the form of ATP. These electron transfer processes may be modulated by conformational dynamics within the protein matrix or at the protein-protein interface, the energetics of which are still not well understood. Photoacoustic calorimetry is an estab-lished method of obtaining time-resolved reaction enthalpy and volume changes on the nanosecond to microsecond timescale. Photoacoustic calorimetry is used here to probe 1) the energetics and volume changes for ET between the self-assembled anionic uroporphy-rin:cytochrome c complex and the role of the observed volume changes in modulating ET within the complex, 2) the enthalpy and volume change for the excited state PCET reac-tion of a tyramine functionalized ruthenium(II) bis-(2,2'-bipyridine)(4-carboxy-4'-methyl-2,2'-bipyrine) meant to be a model for the tyrosine PCET chemistry carried out by cyto-chrome c oxidase and photosystem II, 3) the enthalpy and volume changes related to car-bon monoxide and tryptophan migration in heme tryptophan catabolic enzyme indoleam-ine 2,3-dioxygenase.
14
Raeker, Tim [Verfasser]. "Full-Dimensional Photodynamics Simulations: From Photoisomerizations to Excited-State Proton Transfer Reactions / Tim Raeker." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1161729526/34.
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Gould, Elizabeth-Ann. "The photochemistry of "super" photoacid n-methyl-6-hydroxyquinolinium and other novel photoacids." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43706.
Повний текст джерелаАнотація:
The photochemistry of several novel photoacids was addressed experimentally and theorectically. Initial studies focused on the excited-state proton transfer (ESPT) of several chiral phtoacids and explored the effects of chirality on ESPT; subsequent studies examined photochemistry and photophysics of "super" photoacid N-methyl-6-hydroxyquinolinium (MHQ). In the initial studies, no enantioselectivity was observed from the chiral photoacids to various chiral proton acceptors. In the later studies examining ESPT in MHQ both experimentally and theoretically, the excited-state acidity constant of the photoacid was determined to be an unprecedented -7, making it the strongest photoacid reported in the literature to-date. Consideration was then given to applications of the novel photoacid including its properties as a photoinitiator in cationic polymerizations and as a photochemical probe in gas-expanded liquids and in the Nafion membrane. In the course of these studies, an interesting fluorescence quenching effect was observed that became the subject of some exploratory studies that suggest a nucleophilic quenching mechanism.
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Harvey, Lilia Cuesta. "Excited state proton transfer in ortho substituted naphthols : Part II Mechanistic studies of ortho allyl-naphthol photocyclizations." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/30017.
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Parada, Giovanny A. "Synthesis of Biomimetic Systems for Proton and Electron Transfer Reactions in the Ground and Excited State." Doctoral thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-251471.
Повний текст джерелаАнотація:
A detailed understanding of natural photosynthesis provides inspiration for the development of sustainable and renewable energy sources, i.e. a technology that is capable of converting solar energy directly into chemical fuels. This concept is called artificial photosynthesis. The work described in this thesis contains contributions to the development of artificial photosynthesis in two separate areas. The first one relates to light harvesting with a focus on the question of how electronic properties of photosensitizers can be tuned to allow for efficient photo-induced electron transfer processes. The study is based on a series of bis(tridentate)ruthenium(II) polypyridyl complexes, the geometric properties of which make them highly appealing for the construction of linear donor-photosensitizer-acceptor arrangements for efficient vectorial photo-induced electron transfer reactions. The chromophores possess remarkably long lived 3MLCT excited states and it is shown that their excited-state oxidation strength can be altered by variations of the ligand scaffold over a remarkably large range of 900 mV. The second area of relevance to natural and artificial photosynthesis that is discussed in this thesis relates to the coupled movement of protons and electrons. The delicate interplay between these two charged particles regulates thermodynamic and kinetic aspects in many key elementary steps of natural photosynthesis, and further studies are needed to fully understand this concept. The studies are based on redox active phenols with intramolecular hydrogen bonds to quinolines. The compounds thus bear a strong resemblance to the tyrosine/histidine couple in photosystem II, i.e. the water-plastoquinone oxidoreductase enzyme in photosynthesis. The design of the biomimetic models is such that the distance between the proton donor and acceptor is varied, enabling studies on the effect the proton transfer distance has on the rate of proton-coupled electron transfer reactions. The results of the studies have implications for the development of artificial photosynthesis, in particular in connection with redox leveling, charge accumulation, as well as electron and proton transfer. In addition to these two contributions, the excited-state dynamics of the intramolecular hydrogen-bonded phenols was investigated, thereby revealing design principles for technological applications based on excited-state intramolecular proton transfer and photoinduced tautomerization.
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Ortiz, Sánchez Juan Manuel. "Excited state intramolecular proton transfer reactions coupled with non adiabatic processes: electronic structure and quantum dynamical approaches." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3311.
Повний текст джерелаАнотація:
Els enllaços d'hidrogen són d'importància universal en química i bioquímica. Les propietats dels enllaços d'hidrogen en l'estat electrònic fonamental han estat estudiades durant molt anys. Malgrat tot, molt poc es coneix sobre les reaccions químiques on intervenen enllaços d'hidrogen en els estats electrònics excitats. Una de les reaccions més interessants són les transferències protòniques intramoleculars en estat excitat (ESIPT de les seves sigles en anglès), ja que juguen un paper crucial en una gran varietat de reaccions químiques fotoquímiques de gran rellevància.Les tècniques més modernes de cinètica química disponibles avui dia, permeten la monitorització dels processos ESIPT fins l'escala de temps del femtosegond. Tot i això, els resultats experimentals acostumen a ser difícils d'interpretar, especialment quan es veuen involucrats processos competitius. Aquests processos addicionals suposen un desafiament extra en l'estudi d'aquestes reaccions. En aquest sentit, la química teòrica i computacional representa una molt versàtil eina de treball, donat l'absolut control que els investigadors poden imposar a sistemes modelitzats aïllats.
Els sistemes moleculars recollits en la present tesi representen exemples directes dels diferents ordres de complexitat que l'estudi teòric (des del punt de vista del càlcul electrònic i dinàmic) del processos ESIPT poden representar: des de la comprensió del aspectes fonamentals del procés, fins a la necessitat d'adoptar estratègies teòriques eficients per tractar la presència de processos no adiabàtics.
Hydrogen Bonds are of universal importance in chemistry and biochemistry. The properties of hydrogen bonds in the electronic ground state have been investigated since long ago. Nevertheless, much less is known about the chemical reactions involving hydrogen bonds in excited electronic states. One of the most interesting reactions are the excited state intramolecular proton transfer (ESIPT) processes, as they play a crucial role in a plethora of photochemical reactions of chemical and biochemical relevance.
The most modern kinetic experimental techniques available today, allow the monitoring of ESIPT processes up to the order of the femtosecond. However, the experimental results are usually difficult to analyze, specially when competitive processes are involved. Those additional processes suppose an extra challenge in the study of this topic. In this sense, theoretical and computational chemistry represents a powerful tool of interpretation, given the absolute control that researchers can impose on modelized isolated systems.
The molecular systems collected in the present thesis represent direct examples of the different orders of complexity that the theoretical study (both from the electronic and dynamical points of view) of ESIPT can represent: from the comprehension of the essentials of the process, to the need of adoption of efficient theoretical strategies to treat the presence of non adiabatic processes.
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Fletcher, Katharyn M. [Verfasser], and Andreas [Akademischer Betreuer] Dreuw. "Quantum Chemical Study of Excited State Proton Transfer in Solvated Organic Molecules / Katharyn M. Fletcher ; Betreuer: Andreas Dreuw." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180611586/34.
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de, La Harpe Kimberly Desneiges. "Femtosecond UV and Infrared Time-Resolved Spectroscopy of DNA: From Well-ordered Sequences to Genomic DNA." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299527926.
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Fukuda, Masanori. "Spectroscopic study on the relaxation phenomena of room temperature ionic liquids and the relation with excited state intramolecular proton transfer reaction." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124446.
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Nesselroth, Susan Marian. "I Substituent effects on carbanion photophysics An application of the energy gap law : II Solvent and geometrical constraints on excited state proton transfer." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30331.
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Guzzo, Mariana Rizzi. "Estudo da complexação da fisetina com ciclodextrinas." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-10072008-143050/.
Повний текст джерелаАнотація:
Neste trabalho de Mestrado, foram feitos estudos do comportamento fotofísico da fisetina em diversos solventes através de medidas de absorção de luz UV-Visível, fluorescência estática e resolvida no tempo e da interação entre fisetina (3,3\',4\',7-tetrahidroxiflavona) e 7-hidroxiflavona com ciclodextrinas ( beta e gama) (CDs) através de experimentos de absorção de luz UV-Visível, sinal induzido de dicroísmo circular, fluorescência estática e resolvida no tempo, anisotropia de estado estacionário e RMN de 1H, focando a dependência destas medidas em função da temperatura e do pH. Os resultados experimentais foram comparados com estudos mecânico-quânticos baseados no modelo semi-empírico SAM1 (AMPAC), e nos funcionais B3LYP e MPW1PW91, da Teoria do Funcional de Densidade, empregando os conjuntos de funções de base 6-311G* e 3-21G**. Os estudos da fisetina em diferentes solventes próticos e apróticos mostraram que a fluorescência da sonda é fortemente dependente do solvente. Resultados experimentais indicam a formação de complexos de inclusão entre as CDs e os flavonóides acima. A fisetina com ?-CD forma complexo de estequiometria 1:1 nos meios neutro/ácido e básico, cujos valores de constante de complexação são 900 +- 100 +_ 240 +_ 90 (L/mol), respectivamente. Os dados teóricos evidenciaram que a inclusão da fisetina na beta-CD ocorre preferencialmente pelo anel fenila. O complexo com a gama-CD apresenta estequiometria de 1:1 em meio ácido/neutro e de 1:2 em meio básico, com constantes de complexação de 94 +- 30 e 130 +- 10 (L/mol), respectivamente. Os estudos com a 7-hidroxiflavona revelaram que somente ocorre a formação de complexos com a beta-CD de estequiometria 1:1 e não há dependência do pH. As constantes de complexação obtidas nos meios ácido/neutro e básico são similares, 1430 +-- 510 e 1220 +- 165 L/mol, respectivamente.In this work, the photophysics of fisetin (3,3\',4\',7-tetrahydroxyflavone) in several solvents was studied through UV-vis absorption spectra, steady-state and time-resolved fluorescence measurements. The interaction between fisetin and 7-hydroxyflavone and cyclodextrins (b- e g-) (CDs) was also investigated by UV-vis absorption spectra, induced signal of circular dichroism, steady-state and time-resolved fluorescence, steady-state anisotropy, and 1H NMR, with dependence on pH and temperature. Some experimental data were compared with quantum-mechanics studies based on the SAM1 (AMPAC) semi-empirical model, as well as with the B3LYP and MPW1PW91 functional models from the Density Functional Theory using the 6-311G* and 3-21G* basis sets. The study of the photophysics of fisetin in protic and aprotic solvents showed a complex behavior and a strong dependence on the solvent. The occurrence of many equilibria between the possible structures of fisetin, e.g. the normal, a few deprotonated ones, and the tautomer due to the excited state intramolecular proton transfer can be responsible for the complex analyses of these experimental data. The spectroscopic measurements show that, at pH 4.0 and 6.5, the complex fisetin - b-CD is formed in a Fis:b-CD 1:1 stoichiometry and an equilibrium constant (K) of 900 ± 100 L/mol. In basic medium (pH 11.5), K decreases to 240 ± 90 L/mol. Molecular modeling points out that the inclusion complex is formed preferentially via entry of the fisetin phenyl group into b-CD. On the other hand, the fisetin - g-CD has a stoichiometry of 1:1 in acid/neutral solutions and of 1:2 in basic conditions. The K values are 94 ± 30 e 130 ± 10 (L/mol), respectively. The 7-hydroxyflavone can only form inclusion complexes with b-CD. The stoichiometry is 1:1 and there is no dependence on pH. Both equilibrium constants determined either in acid or basic medium is very similar to each other, 1430 ± 510, and 1220 ± 165 L/mol, respectively. For this reason, we suppose that the inclusion of this compound into b-CD is also through the phenyl ring of the flavonoid.
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Mondek, Jakub. "Časově rozlišená fluorescence ve výzkumu interakcí hyaluronanu a koloidních systémů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-371154.
Повний текст джерелаАнотація:
The aim of the doctoral thesis was to study advanced fluorescence techniques and its use in colloids or hyaluronan-surfactant systems and hydrogels based on hyaluronan, respectively. Steady-state and time-resolved fluorescence were used to study excited state proton transfer fluroescen probes in hyaluronan-surfactant systems to asses the influence of hyaluronan hydration to its interactions with oppositely charged surfactants. Firstly, different excited state proton transfer fluorescence probes were discussed to choose the most suitable candidate for next research. The influence of hyaluronan on inner environment of micells was determined based on the sensitivity of excited state proton transfer of chosen fluorescence probe 1-naphtol and, based on above mentioned experiments, the structure of hyaluronan hydration shell was discussed. The next part of doctoral thesis was focused on fluorescence lifetime correlation spectroscopy and on the development of method of nanorheology. Measured correlation functions were transformed to mean square displacement with developed MATLAB script. Firstly, the fluorescence method was compared with well described methods such as videomicrorheology and dynamic light scattering to asses the reliability of fluorescence correlation spectroscopy in microrheology. Secondly, nanorheology method was developed and its use in passive nanorheology of hyaluronan hydrogels was discussed. Based on mentioned experiments, the fluorescence correlation spectroscopy microrheology and nanorheology methods were optimized to use the methods in hydrogel research.
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香里, 藤井, and Kaori Fujii. "Time-resolved spectroscopic study on fundamental chemical reactions in a unique class of solvents." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13158494/?lang=0, 2021. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13158494/?lang=0.
Повний текст джерелаАнотація:
多数の溶媒分子に取り囲まれている溶液中において溶質分子の化学反応素過程を考える場合、溶媒分子による反応の平衡論的、動的な効果を考える必要がある。本研究では、ユニークな反応場として水や有機溶媒とは区別される、超臨界流体とイオン液体をとり上げ、溶質分子のプロトン移動反応、光解離反応について、時間分解レーザー分光と分子動力学計算、理論的解析を行い、その現象を明らかにする試みをおこなった。In solution, solvent molecules involve chemical reaction of solute molecules and could alter both reaction yield and kinetics. In this thesis, the author focused on fundamental chemical reactions (intermolecular proton transfer and photodissociate reaction) in a unique class of solvents, supercritical fluids and ionic liquids. By measuring time-resolved fluorescence spectrum and transient absorption spectrum of solutes, the author discusses how the reaction yield and kinetics are described by solvent physicochemical properties.
博士(理学)
Doctor of Philosophy in Science
同志社大学
Doshisha University
26
Lukeman, Matthew Joseph. "Excited state intramolecular proton transfer (ESIPT) to aromatic carbon." 2003. http://hdl.handle.net/1828/368.
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Behin, Aein Niloufar. "Photochemical and photophysical studies of Excited State Intramolecular Proton Transfer (ESIPT) in biphenyl compounds." Thesis, 2010. http://hdl.handle.net/1828/2944.
Повний текст джерелаАнотація:
This Thesis aims to examine the effects of substituents on the adjacent proton accepting phenyl ring with respect to a new type of excited state intramolecular proton transfer (ESIPT) process discovered by Wan and co-workers. Therefore, a number of 2-phenylphenols 23-28 were synthesized with electron-donor and electron-acceptor substituents such as methyl, methoxy, and ketone moieties on the adjacent proton accepting phenyl ring.
The results obtained from examination of photochemical deuterium exchange showed that all derivatives except for ketone 27 underwent deuterium exchange (Фex = 0.019 - 0.079), primarily at the 2’-position on photolysis in D2O-CH3CN. In general, compounds with methoxy moiety (ies) on the adjacent proton accepting ring showed higher deuterium exchange yields.
Diol 28 has the potential to undergo photosolvolysis as well as ESIPT process since it has both a benzyl alcohol and a phenol chromophore on the same molecule. Irradiation of 28 in 1:1 H2O-CH3OH gave the corresponding methyl ether product in high yield. Photolysis of 28 in 1:1 D2O-CH3OH also showed that ESIPT competes very well with photosolvolysis. Thus, this work has established that ESIPT can compete efficiently with photosolvolysis.
Semi-empirical AM1 (examination of HOMOs and LUMOs) calculations show a large degree of charge transfer in the electronic excited state (except 27), from the phenol ring to the attached phenyl ring of the studied compounds. The AM1 calculation for ketone 27 showed that the carbonyl oxygen is more basic than the carbon atoms of the benzene ring, which explains the lack of deuterium exchange observed for 27.
28
Guo-Yi, Gao, and 高國益. "Excited-State Proton Transfer and Excited-State De-hydrogen bonding of the Push-Pull Styryl System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/02444281004496751514.
Повний текст джерелаАнотація:
碩士國立嘉義大學
應用化學系研究所
94
To understand the influence of substituents and solvent effect on intramolecular charge transfer (ICT), absorption and emission spectra were measured for several derivatives of 2-styrylquinoline (2-StQ), 2-styrylpyridine (2-StP), 2-styrylthiophene (2-StT), and p-N, N-dimethylamino-2-styrylnaphthalene (2-StN-NMe2) system. A strong donor, such as an N, N-dimethylamino group can produce an ICT compound in these systems, and the excited state dipole moments were measured using a solvatochromic method. The excited-state reaction of push-pull styryl system was studied in this work. The influence of hydrogen bonding (HB) and protonation on an intramolecular charge transfer (ICT) compound, such as compounds of 2-StP-NMe2, 2-StQ-NMe2, 4-StQ-NMe2 and 4-StP-NMe2 etc. The absorption and emission spectra for push-pull styryl system were studied in aprotic dichloromethane and at various acid concentrations. Monoprotonated or doubly protonated forms are present depending on the acid concentration. Excited state deprotonation of the doubly protonated form is observed in aprotic dichloromethane solvent for compounds with two protonation sites. Protonation and hydrogen bonding at acceptor site show red shift in absorption maxima. Interaction at donor site gives the opposite result. Compounds of 2-StQ-NMe2, 2-StP-NMe2, 4-StQ-NMe2, and 4-StP-NMe2 etc. possess a sufficiently large acidity change for the proton transfer process to occur. For compounds 2-StT-NMe2 and 2-StN-NMe2 the acidity change is too small to induce the proton transfer process. A new type of excited-state de-hydrogen bond (ESDHB) process was observed in this study. It is possible to explore the polarity and HB effect of solvent simultaneously by using the ESDHB mechanism. The sensitivity for various compounds in exploring the polarity and hydrogen bond of the medium was compared with the Stokes shift in different solvent. The influences of rigid medium to ICT were also studied for several compounds. We did not find any influence of viscosity to ICT even in iced ethylene glycol. The inclusion complex between α-cyclodextrin or HP-β-cyclodextrin with different compounds were recorded for studying the application of theses compounds in bio-system. The dielectric constant values of the α-cyclodextrin or HP-β-cyclodextrin cavities probed by different compounds are between 5.0 to 10 and 15 to 25 respectively because of the difference in size of the probe molecule inside the cavity.
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Chen, Young-Chang, and 陳永昌. "Excited-State Intramolecular Proton Transfer in 10-Hydroxybenzo[h]quinoline." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/55247241905897481395.
Повний текст джерелаАнотація:
博士國立中正大學
化學研究所
88
Abstract The dynamics of excited state intramolecular proton transfer (ESIPT) in 10-hydroxybenzoquinoline (HBQ) and its deuterated analogue (DBQ) have been investigated by steady-state fluorescence spectroscopy, femtosecond fluorescence upconversion in combination with pump-probe transient absorption experiments. In cyclohexane the time scale for both proton and deuterium transfer in the excited state cannot be resolved under the response limit of the upconversion signal of ca.180 fs. Conversely, the proton-transfer rate is estimated to be ca. 150 fs-1 in DBQ through the transient absorption experiment. The results in combination with a steady-state deuterium isotope steady-state measurement lead us to conclude an ESIPT rate of ~100fs-1 for HBQ in cyclohexane. The initially prepared keto-tautomer is in a highly vibronically (and possibly electronically coupled) excited state of which the time-dependent spectral evolution is both excitation and probe wavelength dependent. It then undergoes vibrational relaxation (and/or internal conversion) in a time scale of several picoseconds, followed by a relatively much longer S1’ S0’ (prime indicates the keto tautomer) decay of 250 ps-1 in cyclohexane. Similar time scales of the proton transfer rate and relaxation dynamics were observed in aprotic solvents. The results lead to a conclusion that ESIPT in HBQ is essentially barrierless and the rate of reaction may be determined within the period of low-frequency, large-amplitude vibrations.
30
Lin, Tsung-Yi, and 林宗毅. "Spectroscopy and Dynamics Study of Excited-State Proton Transfer Reaction." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27537316902553008181.
Повний текст джерела
31
林勇國. "Excited-State Double-Proton Transfer of 7-Azaindole Hydrogen-Bonded Complexes." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/84031122721995721599.
Повний текст джерелаАнотація:
碩士輔仁大學
化學學系
85
My thesis can be divided into two parties: The first, we study the photophysical phenomena of 7-azaindole and different kinds of phosphoric ester. When we excited the complexes of 7-azaindole and short alkane chain of phosphoric ester, we can get the tautomer form emission. When the concentration of phosphoric ester were increase to 3*10-4M, we can observe a blue shift of F2 band emission. On the other hand; in the complexes of 7-azaindole and long alkane chain phosphoric ester system, we can not get the blue shift of the F2 band. We think the blue shift is due to the hydrophobic property of long alkane chain, which stop the getting closer of the other ester. As a result, the local polarity around the complex does not favorite to the existence of ion pair species. The other, we study of the photophysical phenomena the 7-azaindole in the AOT reverse micelles and it'sheavy atom effect. By the UV-Vis spectroscopy and fluorescence spectroscopy we can sure the 7-azaindole get into the reverse micelles. The fluorescence probe was sure in three regions: the core of reverse micelles, ester group region and hydropliobic group region. We can estimate the concentration of the probe by our equation. In the reverse micelles tl complexes of 7-azaindole and acetic acid were distribu the ester group region and hydrophobia region. When water and methanoi in the reverse micelle, location of 7-Azaindole were be in core of reverse micelle. When much more water, the range of water pool will be gettii larger. At final, all of the 7-azaindole were in the center water pool, not in the range of bounding water.
32
Hsu, Chia-Jung. "Spectroscopy and Femtosecond Dynamics of Excited-State Proton / Charge Transfer Reaction." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-0307200710321700.
Повний текст джерела
33
Chen, Yi-An, and 陳怡安. "The fundamental research and application of excited-state proton transfer molecules." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/vxkp2r.
Повний текст джерелаАнотація:
博士國立臺灣大學
化學研究所
106
Chapter 1 Locked ortho- and para-Core Chromophores of Green Fluorescent Protein; Dramatic Emission Enhancement via Structural Constraint We report the design strategy and synthesis of a structurally locked GFP core chromophore p-LHBDI, its ortho-derivative, o-LHBDI, and H2BDI possessing both paraand ortho-hydroxyl groups such that the inherent rotational motion of the titled compounds has been partially restricted. o-LHBDI possesses a doubly locked configuration, i.e., the seven-membered ring hydrogen bond and five-membered ring C(4-5-10-13-14) cyclization, from which the excited-state intramolecular proton transfer takes place, rendering a record high tautomer emission yield (0.18 in toluene) and the generation of amplified spontaneous emission. Compared with their unlocked counterparts, a substantial increase in the emission yield is also observed for p-LHBDI and H2BDI in anionic forms in water, and accordingly the structure versus luminescence relationship is fully discussed based on their chemistry and spectroscopy aspect. In solid, o-LHBDI exhibits an H-aggregate-like molecular packing, offers narrow-bandwidth emission, and has been successfully applied to fabricate a yellow organic light emitting diodes (λmax = 568 nm, ηext = 1.9%) with an emission full width at half-maximum as narrow as 70 nm. Chapter 2 Harnessing Excited-State Intramolecular Proton-Transfer Reaction via a Series of Amino-Type Hydrogen-Bonding Molecules A series of new amino (NH)-type hydrogen-bonding (H-bonding) compounds comprising 2-(2’-aminophenyl)-benzothiazole and its extensive derivatives were designed and synthesized. Unlike in the hydroxyl (OH)-type H-bonding systems, one of the amino hydrogens can be replaced with electrondonating/withdrawing groups. This, together with a versatile capability for modifying the parent moiety, makes feasible the comprehensive spectroscopy and dynamics studies of amino-type excited-state intramolecular proton transfer (ESIPT), which was previously inaccessible in the hydroxyl-type ESIPT systems. Empirical correlations were observed among the hydrogen-bonding strength (the N−H bond distances and proton acidity), ESIPT kinetics, and thermodynamics, demonstrating a trend that the stronger N−H•••N hydrogen bond leads to a faster ESIPT, as experimentally observed, and a more exergonic reaction thermodynamics. Accordingly, ESIPT reaction can be harnessed for the first time from a highly endergonic type (i.e., prohibition) toward equilibrium with a measurable ESIPT rate and then to the highly exergonic, ultrafast ESIPT reaction within the same series of amino-type intramolecular H-bond system. Chapter 3 N-H-Type Excited-State Proton Transfer in Compounds Possessing a Seven-Membered-Ring Intramolecular Hydrogen Bond A series of compounds containing 5-(2-aminobenzylidene)-2,3-dimethyl-3,5-dihydro- 4H-imidazol-4-one (o-ABDI) as the core chromophore with a seven-membered-ring N-H-type intramolecular hydrogen bond have been synthesized and characterized. The acidity of the N-H proton and thus the hydrogen-bond strength can be finetuned by replacing one of the amino hydrogen atoms by a substituent R, the acidity increasing with increasing electron-withdrawing strength of R, that is, in the order H < COCH3 < COPh < Tosyl < COCF3. The tosyl and trifluoroacetyl derivatives undergo ultrafast, irreversible excited-state intramolecular proton transfer (ESIPT) that results in proton-transfer emission solely in the red region. Reversible ESIPT, and hence dual emission, involving the normal and proton-transfer tautomers was resolved for the acetyl- and benzyl-substituted counterparts. For o-ABDI, which has the weakest acidity, ESIPT is prohibited due to its highly endergonic reaction. The results clearly demonstrate the harnessing of ESIPT by modifying the proton acidity and hydrogen-bonding strength in a seven-membered-ring intramolecular hydrogen-bonding system. For all the compounds studied, the emission quantum yields are weak (ca. 10-3) in dichloromethane, but strong in the solid form, ranging from 3.2 to 47.4 %. Chapter 4 Control of the Reversibility of Excited-State Intramolecular Proton Transfer (ESIPT) Reaction: Host-Polarity Tuning White Organic Light Emitting Diode on a New Thiazolo[5,4‑d]thiazole ESIPT System By using the thiazolo[5,4-d]thiazole (TzTz) moiety as the core of a proton acceptor, compounds 2,2′-(thiazolo[5,4- d]thiazole-2,5-diyl)bis(4-tert-butylphenol) (t-HTTH) and 4-tertbutyl-2-(5-(5-tert-butyl-2-methoxyphenyl)thiazolo[5,4-d]thiazol-2-yl)-phenol (t-MTTH) have been strategically designed and synthesized. Upon photoexcitation, both t-HTTH and t-MTTH undergo a reversible type excited-state intramolecular proton transfer (ESIPT), the underlying mechanism of which has been verified by femtosecond early relaxation dynamics in various solvents. The pre-equilibrium in the excited state leads to both normal (∼ 440 nm) and proton-transfer tautomer (∼ 560 nm) emissions, for which the intensity ratio is dependent on both the molecular structure and the polarity of surrounding media. As a result, the emission can be widely tuned from blue to yellow via white-light luminescence. On the basis of t-MTTH, a white organic light emitting diode (WOLED) was successfully fabricated, which achieved external quantum efficiency (ηext) of 1.70% with Commission Internationale de L’Eclairage coordinates of (0.29, 0.33). More importantly, the electroluminescent spectra show superior color stability that is independent of luminance. The result demonstrates for the first time a credible WOLED based on a unimolecular ESIPT reaction, which may have far-reaching implications for practical application. Chapter 5 Molecular Energy Storage Exploiting Thermally Activated Delayed Fluorescence (TADF) Molecules exhibiting thermally activated delayed fluorescence (TADF) possess proximal energy level between the lowest lying excited singlet (S1) and triplet (T1) states. Thus, the energy level of their T1 state can be readily assessed once knowing either S0 → S1 absorption or S0 ← S1 emission gap. This benefits application of TADF molecules utilizing the triple state as a sensitizer for energy transfer. On this basis, we report the new concept that utilizes a thermally activated delayed fluorescence (TADF) core phenoxazine–triphenyltriazine (PX-TZ) coupled with norbornadiene (NBD), (1s,4s)-bicyclo[2.2.1]hepta-2,5-diene, to form an efficient energy storage diad PXTZ-NBD. PXTZ-NBD exhibits an optimum absorption that covers the solar spectrum up to 460 nm. Upon exciting PXTZ-NBD, PXTZ serves as a sensitizer to sensitize NBD triplet state via triplet-triplet energy transfer, followed by the conversion of NBD to a quadricyclane system (QC), namely tetracyclo[3.2.0.02,7.04,6]heptane, forming a PXTZ-QC product that is thermally stable but convertible back to PXTZ-NBD promptly via catalytic reaction. The uniqueness lies in that the degree of photo-conversion and thermal-reverse-conversion can be directly monitored by TADF in both intensity and relaxation dynamics. The PXTZ-NBD ↹ PXTZ-QC photo-thermal conversion renders the energy storage densities of 177 kJ/mol with good durability evidenced by negligible side products after five photo-thermal conversion cycles. This generates a TADF based solar-thermal energy storage system, for which optimal (≤ 460 nm) solar energy is harvested.
34
Chou, Yi-Hsuan, and 周宜萱. "Studies of Excited - State Intramolecular / Intermolecular Systems of Proton Transfer Current Interest." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/73673840204815291946.
Повний текст джерелаАнотація:
碩士國立中正大學
化學研究所
88
The researching of the systems of proton transfer has been becoming more and more important since Waller presented his outstanding report of the proton transfer effect of methyl salicylate in 1955. Above all, the double proton transfer progression of DNA is the best remarkable one. Herewith, I prepared this memoir for illustrating some examples of proton transfer molecules with steady state system and pulse laser system to study their excited-state intramolecular / intermolecular systems of proton transfer. Primarily, we attempted to utilize the 4ABI (4-Azabenzimidazole) molecular mode, which has more intimate with adenosine molecule than 7AI (7-Azaindole) to study the possibility of excited-state intermolecular systems of proton transfer for reaching the goal of the simulation of approximating the malposition of DNA gene mode. Then, in order to detect the triplet state of excited-state proton transfer molecules, we synthesized their iodic derivation molecular developed, and with the heavy atom effect to enhance the emission of these molecules as better as good enough for proving. On the third place, for researching the excited-state proton transfer effect on that adduct, 5-Hydroxyflavone, which has very slight emission whether the 5-Hydroxyflavone is proton transferred or not, we used the ICCD (Image Intensified Charge Coupled Detector) companion the LIF (laser induce fluorescence) effect therewith question its dynamics. At lastly, what the influence of the excited-state intramolecular proton transfer by isotope effect on HBQ (10-Hydroxybenzo[h]quinoline) and its proton transfer dynamical mechanism in non-polar solvents is our major interesting.
35
Liu, Jiun-Chi, and 劉俊騏. "A New Class of Amino-Type Excited-State Intramolecular Proton-Transfer Molecules." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/958qbg.
Повний текст джерела
36
Wu, Guo-Ray, and 吳國瑞. "The Intramolecular and Host/Guest Types of Excited-State Proton Transfer Reaction." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/71040220863836682037.
Повний текст джерелаАнотація:
博士國立中正大學
化學研究所
90
The proton transfer depicts one of the most fundamental processes involved in chemical reactions as well as in living systems. Enormous numbers of research projects have been published regarding various types of proton transfer in ground as well as in the excited states. In my dissertation, the focus is mainly limited to the subject related to the excited-state proton transfer (ESPT) process, forming a proton-transfer tautomer. Correspondingly, photoinduced process involving excited-state proton dissociation and/or protonation in bulk solvents or cluster, which has also been an active topic and has received significant attention, was excluded. One who is interested in this topic can refer to the recent article published by Solntsev et al. Instead, my main goal aims at bifunctional molecules possessing a proton donor group and a proton acceptor group so that ESPT takes place either intramolecularly (i.e. intrinsically) or through the assistance of the guest molecules.
37
Cheng, Chung-Chih, and 鄭仲志. "The Intramolecuar and Host/Guest Type of Excited-State Proton Transfer and Charge Transfer Reactions." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/15573584804114649450.
Повний текст джерелаАнотація:
博士輔仁大學
化學系
91
Abstract Contemporary progress regarding guest/host types of excited-state double proton-transfer has been reviewed, among which are the biprotonic transfer within doubly H-bonded host/guest complexes, the transfer through a solvent bridge relay, the intramolecular double proton transfer and solvation dynamics coupled proton transfer. Of particular emphases are the photophysical and photochemical properties of excited-state double proton-transfer (ESDPT) in 7-azaindole and its corresponding analogues. From the chemical aspect, two types of ESDPT reaction, namely the catalytic and non-catalytic types of ESDPT, have been classified and reviewed separately. For the case of static host/guest hydrogen-bonded complexes both hydrogen-bonding strength and configuration (i.e. geometry) play key roles in accounting for the reaction dynamics. In addition to the dynamical concern, excited-state thermodynamics are of importance to fine-tune the proton transfer reaction in the non-catalytic host/guest type of ESDPT. The mechanisms of protic solvent assisted ESDPT, depending on host molecules and proton-transfer models, have been reviewed where the plausible resolution is deduced. Particular attention has been given to the excited-state proton-transfer dynamics in pure water, aiming at its future perspective in biological applications. Finally, the differentiation in mechanism between solvent diffusive reorganization and solvent relaxation to affect the host/guest ESPT dynamics is made and discussed in detail. Sub-Abstract Chapter 2 The carboxylic acid catalyzed excited-state amino-imino tautomerism for b-carboline (b-CB) and its analogues has been investigated. Thermodynamics and microsolvation (i.e. stoichiometry of the complex formation) of various b-CB/acetic acid complexes in nonpolar solvents have been studied by means of absorption and emission titration experiments. Supplementary support of the stoichiometric ratio and structure for the hydrogen-bonding formation was provided by molecular design and syntheses of various b-CB analogues incorporating either only one hydrogen bonding site or dual hydrogen bonding sites where interplay between two sites are sterically prohibited. The results in combination with time-resolved measurements and theoretical approaches suggest the 1:2 b-CB/acetic acid complex with a structure of triple hydrogen bonding formation to be responsible for the excited-state proton-transfer tautomerism in cyclohexane. The proton transfer time is beyond the response limit of the detecting system of 15 ps, indicating that only a negligibly small geometry adjustment is required for the guest molecule (i.e. acetic acid) to a correct geometry, i.e. a hydrogen-bond relay configuration, for the triple proton transfer to proceed. In comparison, for the 1:1 b-CB/acetic acid non-hydrogen-bond relayed complexes, amino-imino tautomerism is prohibited during the excited-state lifetime, giving rise to a normal Stokes shifted emission. The results provide detailed ground-state thermodynamics of b-CB HB complexes as well as the dynamics of proton-transfer tautomerism mediated by the hydrogen-bonding structures. Sub-Abstract Chapter 3 Comprehensive spectroscopic and dynamical studies on the dual excitation behavior of proton vs charge transfer for 4-(dimethylamino)-1H -pyrrolo[2,3-b]pyridine (DPP) and its related derivatives are reported. In cyclohexane, DPP dimer and/or dual hydrogen-bonded complex are formed with association constants Ka as high as ~ 4.2 x 10E3 and 5.2x10E4 M-1 (e.g., the DPP/acetic acid complex) at 298 K, respectively, which upon electronic excitation undergo ultrafast rate (>> 6.7 x10E10 s-1) of double-proton transfer, resulting in a unique tautomer emission. Dual fluorescence was observed in polar, aprotic solvents, in which the large Stokes shifted emission band originates from the charge-transfer species incorporating a dimethylamine and pyridine ring as electron donor and acceptor, respectively. Detailed solvent-polarity and temperature -dependent studies in combination with theoretical approaches have been performed to determine the excited-state charge-transfer properties such as dipole moment, orbital configuration, etc. Supplementary support for the dual charge/proton-transfer behavior was provided by the comparative spectroscopy and dynamics of various DPP-related derivatives. Further time-resolved measurements conclude that dual emissions share a common Franck-Condon excited state but undergo two independent relaxation channels. In protic solvents, such as ethanol, following fast solvent relaxation dynamics, the excited charge-transfer state further undergoes a solvent (i.e. alcohol) assisted proton transfer reaction. The charge versus proton-transfer emission can be distinguished via the temporal spectral evolution. The results demonstrate DPP to be a unique model among 7-azaindole analogues in which the interplay between charge and proton-transfer reactions is operative in the excited state. Sub-Abstract Chapter 4 The interplay between excited-state intramolecular proton-transfer (ESIrPT) and excited-state intermolecular proton-transfer (ESIePT) reactions in 5-membered N-H---N hydrogen-bonding systems has been explored through design and syntheses of a series of 5-(2-pyridyl) 1-H-pyrazoles 1a-d. In cyclohexane, 1a-d exists predominantly as a monomer form at < 5.0 x10E-6 M, in which ESIrPT takes place with relatively slow rate of <10E11 s-1, resulting in an imine-like tautomer emission maximum at ~600 nm. The ESIrPT mechanism was confirmed through steady-state spectroscopy, relaxation dynamics and controlled experiments on corresponding methylated analogues. The results demonstrate for the first time a unique system among ESIrPT molecules, in which ESIrPT incorporates an appreciably large energy barrier fine-tuned by the skeletal reorganization. Upon increasing the concentration dual hydrogen bonded dimer was formed in 1a-d. Thermodynamics of self-association were determined by the concentration-dependent absorption studies, from which the association constant Ka was deduced to be e.g. ~ 35 M-1 in 1d. The cyclic dual hydrogen bonded dimer undergoes an ultrafast rate (>> 6 x10E11 s-1) of ESIePT, resulting in an imine/amine dimer emission maximized at 560 nm. Further support was rendered by the temperature dependent study, in which the cyclic dimer prevails at low temperature, giving salient ESIePT features. The interplay between ESIrPT and ESIePT with their associated different spectral and relaxation dynamics makes 1a-d systems unique for probing intra- versus intermolecular proton transfer reaction.
38
Yi-Ming, Cheng. "Spectroscopy and Femtosecond Dynamics toward the Excited State Proton/Electron Transfer Coupled Reactions." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-0507200521185600.
Повний текст джерела
39
Hsieh, Cheng-Chih, and 謝承志. "Femtosecond Time-Resolved Spectroscopy in Studying Excited-State Electron and Proton Transfer Reactions." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/88631355503587708259.
Повний текст джерелаАнотація:
博士國立臺灣大學
化學研究所
98
Contemporary progress on organic dyes undergoing excited-state electron and/or proton transfers is reviewed via three aspects: (1) the fundamental view on the mechanistic of electron transfer reaction, i.e., adiabatic versus nonadiabatic processes, and their applications in e.g. ion recognition; (2) excited-state proton transfer (ESPT) in view of hydrogen bonding configuration; (3) the role of solvation and solvation dynamics in the proton transfer coupled charge transfer reactions and (4) excited-state intramolecular proton transfer (ESIPT) reaction of ortho-green fluorescent protein core chromophore. For (1), of particular emphasis are bipolar molecules, for which the electron donor (D) and acceptor (A) are linked by non-π-conjugated covalent bonds. As for altering the distance between D and A via rigid spacers, the electron transfer process can be fine-tuned from adiabatic to nonadiabatic. Relevant fundamentals and applications are briefly reviewed and discussed. For (2), prototypes of intramolecular ESIPT are classified into five-, six-, and seven-membered ring hydrogen-bonding systems. While five- and six-membered hydrogen-bonding systems are somewhat common, seven-membered one is rare. In this section, in addition to those of 5- and 6-membered classes, paradigms of 7-membered hydrogen-bonding systems are presented by using analogue of green fluorescent protein core chromophore. On the other hand, the ESPT dyanmcis via intermolecular hydrogen bonding has also been reviewed. Particually, a four 6HIQ is strategically designed and synthesized; it possesses a central moiety of 7-azaindole (7AI) and undergoes excited-state double proton transfer (ESDPT). Despite a barrierless type of ESDPT in the 6HIQ dimer, femtosecond dynamics and a kinetic isotope effect provide indications for a stepwise ESDPT process in the 6HIQ/7AI heterodimer. In (3), various mechanisms of protic solvent assisting ESPT are reviewed, among which plausible mechanism is deduced and discussed. Particular attention is paid to reaction dynamics in alcohol and aqueous solutions, with an aim toward biological applications. In this section, the interplay between excited-state charge and proton transfer reactions in protic solvents is investigated in a series of 7AI derivatives can undergo methanol catalyzed ESDPT, resulting in dual (normal and proton transfer) emission. Instead, the normal emission undergoes prominent solvatochromism. Detailed relaxation dynamics and temperature dependent studies are carried out. The result is remarkably different from 7AI, which is also unique among most excitedstate electron/proton transfer coupled systems studied to date. Last but not least, the differences in how solvent diffusive reorganization and solvent relaxation affect the ESPT dynamics are discussed; the conclusions should provide more insight into the micro- and macro-solvation processes. Subsequently, the fluorescence spectroscopy and femtosecond relaxation dynamics of diCN-HBO anddiCN-HBT are studied to probe the ESIPT coupled electron transfer (ESIET) reaction. Unlike most of the ESIPT/ESIET systems previously designed, in which ESIET takes place prior to ESIPT, both diCN-HBO and diCN-HBT undergo ESIPT, concomitantly accompanied with the charge transfer process, such that the ESIPT reaction dynamics are directly coupled with solvent polarization effects. The long-range solvent polarization interactions result in a solvent-induced barrier that affects the overall proton transfer reaction rate. A prototypical system has been demonstrate in which the photon-induced nuclear motion (proton transfer) is directly coupled with solvent polarization and the corresponding mechanism is reminiscent of that applied in an electron transfer process. In (4), the ESIPT reaction of ortho-green fluorescent protein (GFP) chromophore, 4-(2-hydroxybenzyli-dene)-1,2-dimethyl-1H-imidazol-5(4H)-one (o-HBDI), has been studied via ultrafast time-resolved spectroscopy. o-HBDI possesses a seven-membered-ring intramolecular hydrogen bond, from which the system response limited (< 150 fs) ESIPT takes place, resulting in a ~602 nm proton-transfer tautomer emission (τf ~ 7.8 ps) in CH3CN. An aim of this study is to probe the structural evolution of o-HBDI during and after ESIPT reaction. The results of UV/Vis transient absorption spectra reveal new absorption bands, providing new insight into the structural evolution of the biomimetic systems during the ESIPT reaction. The appearance of long-lived absorption band at ~580 nm in CH3CN firmly supports the existence of ground state tautomer isomer which cannot be detected in the fluorescence upconversion. Further nanosecond transient absorption spectra resolve this transient species with a lifetime of as long as ~24μs. It is thus concluded that upon electronic excitation, ESIPT takes place in o-HBDI, forming a hydrogen bonded keto-isomer, which then undergoes cis-trans isomerization either along the one-bond-flip of exocyclic C-C double bond or via the concerted twist around the bridging C=C-C bonds, i.e. a hula type of twist, giving a long-lived trans-keto isomer at ground state followed by a 24 μs deprotonation rate. The results of viscosity dependent dynamics are in favor of the former mechanism, i.e. one-bond-flip with large amplitude motion.
40
Cheng, Yi-Ming, and 鄭宜明. "Spectroscopy and Femtosecond Dynamics toward the Excited State Proton/Electron Transfer Coupled Reactions." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/45112949400617549473.
Повний текст джерелаАнотація:
博士國立臺灣大學
化學研究所
93
Part 1: Detailed insights into the excitation behaviors for charge versus proton transfer in para-N,N-ditolylamino-salicylaldehyde (Ia) have been gained via luminescence spectroscopy and femtosecond dynamics. In cyclohexane, following an ultrafast rate (~2.0x1012 s-1) of excited-state intramolecular proton transfer (ESIPT), fast equilibrium takes place between normal (N*) and tautomer excited states (T*), resulting in dual fluorescence maximized at 450 and 540 nm, respectively, with a common population decay rate of 360 ps-1. The normal emission exhibits drastic solvent-polarity dependence and has been concluded to originate from a charge-transfer species incorporating excited-state intramolecular charge transfer from ditolylamine to carbonyl oxygen. In dipolar solvents, competitive rates between ESIPT and solvent relaxation were observed, and the solvated charge-transfer state is thermodynamically more favorable, so that the T*-N* reverse proton transfer takes places. Supplementary supports were provided by the corresponding experiments for the methoxy derivative of Ia as well as other relevant analogues. The results shed light on detailed proton/charge transfer coupled dynamics as well as the associated solvent-relaxation dynamics at an early time domain. Part 2: The excitation behaviors for 4’-N,N-diethylamino-3-hydroxyflavone (Ia) and 4’-N,N-diethylamino-3-methoxyflavone (Ib) have been investigated via femtosecond fluorescence upconversion approaches to gain detailed insights into the mechanism of proton/charge transfer coupling reaction. In polar solvents such as CH2Cl2 and CH3CN, Ib undergoes an excited state intramolecular charge transfer (ESICT) reaction, and its early fluorescence decay correlates well with the solvent relaxation dynamics, resulting in a continuously time-dependent Stokes shifted emission. For the case of Ia, in addition to a slow, solvent-polarity dependent rate (a few tens of picoseconds-1) of excited state intramolecular proton transfer (ESIPT) reported previously, early femtosecond relaxation dynamics clearly reveal that the proton-transfer tautomer emission consists of a rise component of a few hundred femtoseconds. The temporal spectral evolution at the time domain of zero to a few hundred femtoseconds further resolves two distinct emission bands consisting of a proton transfer tautomer emission and a time-dependent Stokes shifted charge transfer emission similar to that observed in Ib. The results, in combination with ab initio calculations on the dipolar vectors for normal and tautomer species in both ground and excited states, lead us to unveil the importance of the relationship of the dipolar vectors among various states, and hence the corresponding solvation energetics, in order to shed light on the overall ESICT/ESIPT coupled reaction in Ia. We conclude a similar dipolar character between ground-state normal (N) and excited proton-transfer tautomer (T*) species, whereas due to ESICT, the normal excited state (N*) possesses a large dipolar change with respect to N and T*. ESIPT is thus energetically favorable at the Franck-Condon excited N*, and its rate is competitive with respect to the solvation relaxation process. After reaching the solvent equilibration, there exists an equilibrium between N* and T* states in e.g. CH3CN. Due to the greatly different equilibrium polarization between N* and T*, both forward and reversed ESIPT dynamics are associated with a solvent induced barrier. The latter viewpoint of the equilibrium type of ESIPT in Ia is in agreement with the previous reports based on steady state,10 picosecond,11, and femtosecond , dynamic approaches. The generalization of mechanism of the dipolar tuning ESIPT/ESICT reaction is also discussed. Part 3: Comprehensive excitation behaviors of 7-N,N-diethylamino-3-hydroxyflavone (I) have been investigated via steady state, temperature dependent emission, and fluorescence upconversion to probe the excited state intramolecular charge/proton transfer (ESICT/ESIPT) coupled reaction. For I in polar solvents such as CH2Cl2 and CH3CN, in addition to a relatively slow, solvent-polarity dependent rate (a few tens of picoseconds-1) of ESIPT, femtosecond dynamics clearly reveals the competitive rates between solvation and proton-transfer dynamics. Firm supports are rendered by the spectral temporal evolution, which resolves two distinct bands, i.e., ESICT and ESIPT emission at < few ps. The results, in combination with ab initio calculations on the dipolar vectors for various corresponding states, lead us to conclude that excited-state normal (N*) and excited proton-transfer tautomer (T*) possesses very different dipole orientation, whereas the dipole orientation of the normal ground state (N) is in between that of N and T*. ESIPT is thus energetically favorable at the Franck-Condon excited N*, and its rate is competitive with respect to solvent relaxation dynamics induced by ESICT. Unlike the well-known ESICT/ESIPT system, 4’-N,N-diethylamino-3-hydroxyflavone, in which equilibrium exists between N* and T*, N*-T* ESIPT for I is a highly exergonic, irreversible process in all solvents studied. Further temperature dependent studies deduce a solvent-polarity perturbed energy barrier of 3.6 kcal/mol in CH3CN. To extend the dipolar tuning ESICT/ESIPT mechanism, 7-N,N-diethylamino-4’-N,N-dimethyl-3-hydroxyflavone (II) was synthesized via addition of the 4’-N,N-dimethyl substituent to I. As a result, the changes of dipolar vector are largely cancelled out, and ESIPT behavior is similar to that of the parent 3-hydroxyflavne in that the proton transfer dynamics is only slightly dependent of solvent polarity. The proposed dipolar tuning mechanism thus generalizes the ESICT/ESIPT coupled reaction dynamics in polar, aprotic solvents.
41
Wu, Yu-Sin, and 吳毓心. "Water-Catalyzed Excited-State Proton Transfer Reactions in 7-Azaindole and Its Analogues." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/25189276906374297606.
Повний текст джерелаАнотація:
碩士國立臺灣大學
化學研究所
102
The mechanism of water-catalyzed excited-state proton transfer (ESPT) reaction for 7-azaindole (7AI) has long been investigated, but there are some controversial viewpoints. Recently, owing to the superiority of sensing biowaters in proteins by a 7AI analogue, 2,7-diazatryptophan, it is timely to reinvestigate water-catalyzed ESPT in 7AI and its analogues in an attempt to unify the mechanism. Herein, a series of 7AI analogues and their methylated derivatives were synthesized to carry out a systematic study on pKa, pKa* and the associated fluorescence spectroscopy and dynamics. The results conclude that all 7AI derivatives undergo water catalyzed ESPT in neutral water. However, for those derivatives with electron-donating substituent (including –H) at C(3), following water catalyzed ESPT to form an excited N(7)-H proton-transfer tautomer, T*, rapid protonation takes place to generate an excited cationic (TC*) species that subsequently undergoes a fast deactivation to the N(1)-H normal species in the ground state. Conversely, protonation in T* is prohibited for those derivatives with an electron-withdrawing groups at the C(2) or C(3), or C(2) atom replaced by an electron-withdrawing nitrogen atom (N(2) in e.g., 2,7-diazatryptophan), giving a prominent green T* emission. Additional support is given by the synthesis of the corresponding N(7)-CH3 tautomer species, for which pKa* of the cationic form, i.e., the N(7)-CH3N(1)-H+ species, is measured to be much greater than 7.0 for those with electron-donating C(3) substituents, whereas it is lower than 7.0 upon anchoring electron-withdrawing groups. For 7AI the previously missing T* emission is clearly resolved with peak wavelength at 530 nm in the pH interval of 13.0-14.5.
42
Cheng, Yi-Ming, and 鄭宜明. "Excited-State Intramolecular Proton Transfer in 5-Hydroxyflavone and 10-Hydroxybenzo[h]quinoline." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/45702879868941115261.
Повний текст джерела
43
Hsieh, Re-Ming Ray, and 謝瑞明. "Ultrafast reaction dynamics studies of excited-state intramolecular proton transfer in gas phase." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/98464097814134442250.
Повний текст джерела
44
Chen, Chi-Lin, and 陳其霖. "Excited-state proton transfer molecules and planarization molecules in fundamental research and application." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2ktvwb.
Повний текст джерелаАнотація:
博士國立臺灣大學
化學研究所
106
We have strategically designed and synthesized several new classes of excited-state proton transfer and planarization molecules In the cases of excited-state proton intramolecular proton transfer compounds, we have synthesized a series amino (NH)-type intramolecular hydrogen-bonding compounds via replacing one of the N–H hydrogen atoms by various substituents. It makes feasible comprehensive spectroscopy and dynamics studies of excited-state intramolecular proton transfer (ESIPT) as a function of N–H acidity. Another cases is excited-state planarization molecules, we deeply investigate the coupling of electronic processes with conformational motions, we exploit a tailored strategy to harness the excited-state planarization of 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) by halting the structural evolution via macrocyclization process, in which the para sites of 9,14-diphenyl are systematically enclosed by a dialkoxybenzene-alkyl-ester or -ether linkage with different chain lengths, imposing various degrees of constraint to impede the structural deformation. Accordingly, a series of DPAC-n (n = 1~8) derivatives were synthesized, in which n correlates with the alkyl length, such that the strength of the spatial constraint decreases as n increases. Furthermore we have thus strategically designed and synthesized a series of methylation structures based on DPAC as a core, where ortho sites of the 9,14-diphenyl moieties are chemically methylation by methyl group with different methylation , forming a series of new DPAC, Mx-My-DAPC (x = 0, 1 or 2, y = 1 or 2). Our aim was to impose various degrees of steric hindrance to distort the V-shape conformation of ground state structure so that we would be able to investigate the near planar structure in ground state. Comprehensive spectroscopic and dynamic studies, together with a computational approach, rationalized the associated excited-state structure responding to emission origin. For all of these cases, which are suitable for fundamental research and applications.
45
Su, Charlene, and 蘇夏琳. "Ultrafast Time-resolved Spectroscopic Studies of Gas-Phase Excited-State Intramolecular Proton Transfer Reactions." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/47285901332047010080.
Повний текст джерела
46
Chen, Hsin Ru, and 陳心如. "Synthesis and Spectroscopy of Fluorogenic Probes Based on the Excited-State Proton Transfer Reaction." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/80456631135109120052.
Повний текст джерелаАнотація:
碩士國立中正大學
化學研究所
85
Design and synthesis of fluorogenic probes based on the excited-stateproton/charge transfer reaction have been carried out in this seminal study.Two major goals oriented in the future application can be specified. The firstpart involves the synthesis of metal ion probe, in which the 15-crown-5functional group acts as a bsais. We expect that the degree of proton/ chargetransfer ratio be fine tuned through the formation of a metal ion/chromophore complex, resulting in a significant change of UV-Vis absorption and fluorescencespectra. For this case, the design of an ultrasensitive sensitive metal ion detecting system may be achieved. For the second part, the ester and phosphate derivatives of 3-hydroxyflavone were synthesized to investigate their activity in reacting with the correspondingenzymes, esterase and alkaline phosphatase, respectively. The dissociated product, 3-hydroxyflavone, has exceptionally high yield of tauyomer emission resulting from the excited-state proton transfer reaction. In contrast, the initialreagent has negligible normal emission due to the lowest n *transition, generatingan ideal fluorogenic system used in the enzyme-linked- immunoassay.
47
Chiu, Chieng-Hwa, and 邱建華. "The Study of Excited State Double Proton Transfer in 7-AI And actam Complexes." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/04213827412961932158.
Повний текст джерелаАнотація:
碩士輔仁大學
化學學系
83
Lactam-Lactim tautomerization via 7-AI(7-azaindole) assisted excited-state double proton has been studied in various lactams, including 2-azacyclohexanone(I),4-azatricyclo[4.3.1.1] undecan-5-one(II),3,4,5,6,8-hexahydro-2(1H)-quinolinone(III). For I-III,lactam-lactim tautomerization is both thermally and photonically inaccessible.Spectra evidence for 7-AI assisted lactam-lactim tautomerization of I and II is provided by the 7-AI tautomer emission (λ~480nmin cyclohexane)resulting from the excited-state double proton transfer(ESDPT).This ESDPT process is proposed to be dependent on the lactam-lactim tautomerization energy,as is supported by the (III)/7-AI hydrogen bonded complex in which the ESDPT reaction is energetically unfavorable due to the high endothermicity of lactam-lactim tautomerization in excited state of III/7-AI complex.
48
Cheatum, Christopher M. "Transient electronic absorption studies of vibrational relaxation and excited-state proton transfer in solution." 2001. http://www.library.wisc.edu/databases/connect/dissertations.html.
Повний текст джерела
49
Guo, Meng-Xin, and 郭孟鑫. "Studies of Three Fundamental Mechanisms : Excited-State Proton/Charge/Energy Transfer Reactions in Solution Phase." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/80477897667714387560.
Повний текст джерела
50
Hsu, Yen-Hao, and 許晏豪. "Synthesis of Excited-State Intramolecular Proton Transfer Compounds via Seven-Membered-Ring Hydrogen Bonding System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/60102131456263511518.
Повний текст джерелаАнотація:
碩士國立臺灣大學
化學研究所
102
In part I, we successfully obtained the bifunctional ortho- green fluorescence protein (o-HBDI) derivative, o-PyMeGFP, synthesized by Knoevenagel type reaction. Due to unstable conformation of o-MePyGFP; However, we successfully synthesized o-PyPhGFP via molecular adjustment. o-PyPhGFP underwent excited-state intramolecular proton transfer process via seven-membered-ring hydrogen-bonding system and its emssion at 607 nm. Also, ZnCl2 was reacted with o-PyPhGFP to form a complex, which destructed intramolecular H-bond and obtained blue emission. In part II, according synthetic route from chapter1, 5-HI and 7-HI were used as starting reactants to obtain a structurally locked GFP core chromophore p-LHBDI, its ortho-derivative, o-LHBDI underwent ESIPT process and enhanced the quantum yield (up to 0.18) at 585 nm. We also synthesized H2BDI possessing both para- and ortho- hydroxyl groups. Anionic H2BDI rendered its emission at 557 nm and quantum yield of 1.3 x 10-3. In part III, 1,2-dibromocyclopent-1-ene was used as starting reactant to link pyridine and pyrrole to obtain the novel compound, 7-HB, possessing intramolecular seven-membered-ring H-bond system. 7-HB rendered tautomer emission at 603 nm. Also, we obtained the methylated compound, 7-NCH3. In part IV, three compounds (8-HB-1, 8-HB-2 and 8-HB-3) which were successfully synthesized may have intramolecular eight-membered-ring H-bond system.