Proton Transfer Dynamics of 4′-N,N-Dimethylamino-3-hydroxyflavone Observed in Hydrogen-Bonding Solvents and Aqueous Micelles
Proton Transfer Dynamics of 4′-N,N-Dimethylamino-3-hydroxyflavone Observed in Hydrogen-Bonding Solvents and Aqueous Micelles
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DOI：
10.1021/acs.jpcb.5b00021
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发表时间：
2015-04-30
影响因子：
3.3
通讯作者：
Mandal, Debabrata
中科院分区：
文献类型：
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作者：
Ghosh, Deborin;Batuta, Shaikh;Mandal, Debabrata
在氢键溶剂中对4′-N， n-二甲胺-3-羟基黄酮荧光团进行了光物理研究。在氢键酸和氢键碱中，从稳态和时间分辨光谱中出现了激发态分子内质子转移（ESIPT）的明确证据。同样的现象也被观察到存在于水性胶束亲水壳区的荧光团，在那里它们与胶束-水界面的水分子密切接触。在这些系统中确定了类似于100 ps ESIPT的慢时间常数，这些时间常数与溶剂化动力学密切相关。缓慢的ESIPT时间常数归因于在黄酮类化合物激发态能表面从溶剂松弛的烯醇形式到互变异构体形式的激活势垒穿越。与早期发生的无障碍ESIPT相比，
Photophysical studies on the 4'-N,N-dimethylamino-3-hydroxyflavone fluorophore were performed in hydrogen-bonding solvents. Both in hydrogen-bonding acids and bases, clear evidence of excited state intramolecular proton transfer (ESIPT) emerged from steady-state and time-resolved spectroscopies. The same was also observed for the fluorophores residing in the hydrophilic shell region of aqueous micelles, where they come into close contact with water molecules at the micelle-water interface. Slow similar to 100 ps ESIPT time-constants were determined in these systems that correlated well with solvation dynamics. The slow ESIPT time-constants are attributed to activated barrier crossing from the solvent-relaxed enol form to tautomer form in the excited state energy surface of the flavone. In contrast to the barrier-less ESIPT occurring in early (