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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ground- and excited-state double proton transfer in lumichrome/acetic acid system: Theoretical and experimental approach
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Ground- and excited-state double proton transfer in lumichrome/acetic acid system: Theoretical and experimental approach

机译：发光铬/乙酸体系中基态和激发态双质子转移的理论和实验方法

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Experimental time-resolved spectral and photon counting kinetic results confirm formation of an isoalloxazinic excited state via excited-state double proton transfer (ESDPT) catalyzed by a carboxylic acid molecule that forms a hydrogen-bond complex with the parent alloxazine molecule. This isoalloxazinic tautomer manifests itself as a distinct long-lived emissive species formed only in such alloxazine derivatives that were not substituted at the N(1) nitrogen atom, being a product of the excited-state reaction occurring from the alloxazinic excited state. Theoretical calculations support the idea that the ESDPT occurs by the concerted mechanism. The calculated activation barrier in the excited state is much lower than the same barrier in the ground state and even disappears for the HOMO-1 to LUMO excitation, which explains the fact that the reaction takes place in the excited-state only. The reaction rate estimated from the emission kinetics is ca. 1.4 x 10(8) dm(3) mol(-1) s(-1) in ethanolic solutions of lumichrome with added acetic acid.
机译：实验时间分辨的光谱和光子计数动力学结果证实，由羧酸分子催化的激发态双质子转移（ESDPT）形成了异四叠氮基激发态，该羧酸分子与母体四恶嗪分子形成氢键络合物。这种异四叠氮基互变异构体自身表现为仅在这种在N（1）氮原子上未被取代的四氮杂嗪衍生物中形成的独特的长寿命发射物种，该衍生物是由四氮杂嗪激发态发生的激发态反应的产物。理论计算支持以下观点：ESDPT是通过协调机制发生的。在激发态下计算出的激活势垒远低于基态下的相同势垒，甚至对于HOMO-1至LUMO激发都消失了，这解释了这一事实，即反应仅在激发态下发生。根据发射动力学估算的反应速率约为。在加有乙酸的发光铬乙醇溶液中加入1.4 x 10（8）dm（3）mol（-1）s（-1）。

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