• 제목/요약/키워드: Excited-state intramolecular proton transfer

검색결과 29건 처리시간 0.049초

TDDFT Potential Energy Functions for Excited State Intramolecular Proton Transfer of Salicylic Acid, 3-Aminosalicylic Acid, 5-Aminosalicylic Acid, and 5-Methoxysalicylic Acid

  • Jang, Sung-Woo;Jin, Sung-Il;Park, Chan-Ryang
    • Bulletin of the Korean Chemical Society
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    • 제28권12호
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    • pp.2343-2353
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    • 2007
  • We report the application of time-dependent density functional theory (TDDFT) to the calculation of potential energy profile relevant to the excited state intramolecular proton transfer (ESIPT) processes in title molecules. The TDDFT single point energy calculations along the reaction path have been performed using the CIS optimized structure in the excited state. In addition to the Stokes shifts, the transition energies including absorption, fluorescence, and 0-0 transition are estimated from the TDDFT potential energy profiles along the proton transfer coordinate. The excited state TDDFT potential energy profile of SA and 3ASA resulted in very flat function of the OH distance in the range ROH = 1.0-1.6 A, in contrast to the relatively deep single minimum function in the ground state. Furthermore, we obtained very shallow double minima in the excited state potential energy profile of SA and 3ASA in contrast to the single minimum observed in the previous work. The change of potential energy profile along the reaction path induced by the substitution of electron donating groups (-NH2 and -OCH3) at different sites has been investigated. Substitution at para position with respect to the phenolic OH group showed strong suppression of excited state proton dislocation compared with unsubstitued SA, while substitution at ortho position hardly affected the shape of the ESIPT curve. The TDDFT results are discussed in comparison with those of CASPT2 method.

Time-resolved Anisotropy Study on the Excited-State Intramolecular Proton Transfer of 1-Hydroxyanthraquinone

  • Choi, Jun-Rye;Jeoung, Sae-Chae;Cho, Dae-Won
    • Bulletin of the Korean Chemical Society
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    • 제24권11호
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    • pp.1675-1679
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    • 2003
  • The photodynamics of excited-state intramolecular proton transfer reaction of 1-hydroxyanthraquinone (1-HAQ) and 1-deuterioanthraquinone was investigated in toluene with time-resolved emission and femtosecond transient transmittance techniques at room temperature. The temporal profiles of transient transmittance of 1-HAQ could be well described with multi-decaying time constants. The ultrafast time constant within ca. 260 fs reflects the dynamics of proton transfer. The decay component of 2 ps is assigned to an additional proton translocation process induced by the intramolecular vibrational relaxation, whereas the decay component of 18 ps is assigned to the vibrational cooling process, while the long component (200 ps) can be explained in terms of the relaxation from excited-state keto-tautomer to its ground state. Time-resolved anisotropy decay dynamics and isotope effects on the photodynamics reveals that the ESIPT from enol-tautomer to keto-one of 1-HAQ is barrierless reaction and coupled to a vibrational relaxation process.

Excited-State Intramolecular Proton Transfer (ESIPT) Fluorescence in a Polymeric System

  • Park, Soo-Young
    • 한국고분자학회:학술대회논문집
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    • 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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    • pp.35-36
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    • 2006
  • Excited-state intramolecular proton transfer (ESIPT) is a phototautomerization occurring in the excited states of the molecules possessing a cyclic intramolecular or solvent-bridged hydrogen bond. Recently, we have developed novel ESIPT chromophores, molecules, dendrimers and polymers which show very high fluorescence quantum efficiency combined with the characteristic features of optical switching, fluorescence patterining, lasing, and electroluminescence. Broad overview of these topics will be given in this talk.

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Application of Excited-State Intramolecular Proton Transfer (ESIPT) Principle to Functional Polymeric Materials

  • Park, Sang-Hyuk;Kim, Se-Hoon;Seo, Jang-Won;Park, Soo-Young
    • Macromolecular Research
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    • 제16권5호
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    • pp.385-395
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    • 2008
  • Synthesis and properties of novel excited-state intramolecular proton transfer (ESIPT) materials, recently developed in our group, are described. Highly efficient ESIPT reaction, achieved in polyquinolines, polybenzoxazoles, and oxadiazole and imidazole derivatives possessing an intramolecular tautomerizable hydrogen bond, has been investigated theoretically and experimentally. It is demonstrated that unique properties arising from the ESIPT process (large Stokes' shift, no self-absorption, and easy population inversion, etc.) make it possible to produce advanced polymer devices for lasing, optical storage, and electroluminescence.

Intramolecular Proton Transfers of 2-hydroxy-4,5-naphthotropone

  • Du-Jeon Jang
    • Bulletin of the Korean Chemical Society
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    • 제12권4호
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    • pp.441-444
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    • 1991
  • The intramolecular proton transfers of 2-hydroxy-4,5-naphthotropone in room temperature solutions are studied using static and time-resolved absorption and emission spectroscopy. Dual normal and tautomer fluorescence is observed in ethanol solution, while only the tautomer fluorescence is observed in cyclohexane solution. The fluorescence lifetimes and quantum yields in ethanol and cyclohexane solutions indicate that in hydrocarbon solvents, rapid intersystem crossing competes with proton transfer in the first excited singlet state. Transient absorption spectra and kinetics indicate that proton transfer also undergoes in the first triplet state with a transfer time of ∼ 3 ns. No transient absorption from the tautomer ground state indicates a rapid back proton transfer in the ground state.

Tailoring the Excited-State Intramolecular Proton Transfer (ESIPT) Fluorescence of 2-(2'-Hydroxyphenyl)benzoxazole Derivatives

  • Seo, Jang-Won;Kim, Se-Hoon;Park, Sang-Hyuk;Park, Soo-Young
    • Bulletin of the Korean Chemical Society
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    • 제26권11호
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    • pp.1706-1710
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    • 2005
  • The excited-state intramolecular proton transfer (ESIPT) fluorescence in the 2-(2'-hydroxyphenyl)benzoxazole (HBO) derivatives with different electron donor and acceptor substituents was studied by spectroscopic and theoretical methods. Changes in the electronic transition, energy levels, and orbital diagrams of HBO analogues were investigated by the semi-empirical molecular orbital calculation and were correlated with the experimental spectral position of ESIPT keto emission. It was found that the presence of substituents, regardless of their nature, resulted in the red-shifted absorption relative to HBO. However, the spectral change of the ESIPT fluorescence was differently affected by the nature of substituent: hypsochromic shift with electron donor and bathochromic shift with electron acceptor.

Ultrafast Excited State Intramolecular Proton Transfer Dynamics of 1-Hydroxyanthraquinone in Solution

  • Ryu, Jaehyun;Kim, Hyun Woo;Kim, Myung Soo;Joo, Taiha
    • Bulletin of the Korean Chemical Society
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    • 제34권2호
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    • pp.465-469
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    • 2013
  • Proton transfer reaction is one of the most fundamental processes in chemistry and life science. Excited state intramolecular proton transfer (ESIPT) has been studied as a model system of the proton transfer, since it can be conveniently initiated by light. We report ESIPT reaction dynamic of 1-hydroxy-anthraquione (1-HAQ) in solution by highly time-resolved fluorescence. ESIPT time of 1-HAQ is determined to be $45{\pm}10$ fs directly from decay of the reactant fluorescence and rise of the product fluorescence. High time resolution allows observation of the coherent vibrational wave packet motion in the excited state of the reaction product tautomer. The coherently excited vibrational mode involves large displacement of the atoms, which shortens the distance between the proton donor and the acceptor. With the theoretical analysis, we propose that the ESIPT of 1-HAQ proceeds barrierlessly with assistance of the skeletal vibration, which in turn becomes excited coherently by the ESIPT reaction.

Excited State Intramolecular Proton Transfer and Physical Properties of 7-Hydroxyquinoline

  • Kang Wee-Kyeong;Cho Sung-June;Lee Minyung;Kim Dong-Ho;Ryoo Ryong;Jung Kyung-Hoon;Jang Du-Jeon
    • Bulletin of the Korean Chemical Society
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    • 제13권2호
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    • pp.140-145
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    • 1992
  • The excited state intramolecular proton transfer and physical properties of 7-hydroxyquinoline are studied in various solutions and heterogeneous systems by measuring steady state and time-resolved fluorescence, reflection and NMR spectra. Proton transfer is observed only in protic solvents owing to its requirement of hydrogen-bonded solvent bridge for proton relay transfer. The activation energies of the proton transfer are 2.3 and 5.4 kJ/mol in $CH_3OH$ and in $CH_3OD$, respectively. Dimers of normal molecules are stable in microcrystalline powder form and undergo an extremely fast concerted double proton transfer upon absorption of a photon, consequently forming dimers of tautomer molecules. In the supercage of zeolite NaY, its tautomeric form is stable in the ground state and does not show any proton transfer.

CONCENTRATION DEPENDENCES OF GROUND-STATE AND EXCITED-STATE INTRAMOLECULAR PROTON TRANSFER OF PIROXICAM IN METHANOL

  • Cho, Dae-Won;Kang, Seong-Gwan;Kim, Yong-Hee;Yoon, Min-Joong;Kim, Dong-Ho
    • Journal of Photoscience
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    • 제1권1호
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    • pp.15-23
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    • 1994
  • The absorption and fluorescence spectral properties of piroxicam (PRX) in the hydrogenbonding solvents show the most sensitive dependence on the concentration ranging from 8 x 10$^{_5}$ to 2 x10$^{_5}$ M. These are attributed to both the solvent-mediated ground-state intermolecular proton transfer (GSIerPT) leading to formation of the ground state anion and the excited-state intmmolecular proton transfer (ESIraPT). The concentration dependences of the time-resolved emission kinetics at both room temperature and 77 K have also been investigated. It is shown that in the excited state, the ESIraPT of PRX is the dominant process to form a keto tautomer at the high concentration, whereas at the low concentration the excited-state conformational change of the anion is an additional process leading to formation of a zwitterion. The ESI~PT of PRX in the hydrogenbonding solvent is coupled with the ultrafast excited-state solvent reorganization.

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