Tseng Huan-Wei, Liu Jun-Qi, Chen Yi-An, Chao Chi-Min, Liu Kuan-Miao, Chen Chi-Lin, Lin Tzu-Chieh, Hung Cheng-Hsien, Chou Yen-Lin, Lin Ta-Chun, Wang Tian-Lin, Chou Pi-Tai
†Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
‡School of Medical Applied Chemistry, Chung Shan Medical University, Taichung 40201, Taiwan.
J Phys Chem Lett. 2015 Apr 16;6(8):1477-86. doi: 10.1021/acs.jpclett.5b00423. Epub 2015 Apr 6.
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 electron-donating/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.
设计并合成了一系列由2-(2'-氨基苯基)苯并噻唑及其多种衍生物组成的新型氨基（NH）型氢键化合物。与羟基（OH）型氢键体系不同，氨基氢中的一个可以被供电子/吸电子基团取代。这一点，再加上修饰母体部分的多种能力，使得对氨基型激发态分子内质子转移（ESIPT）进行全面的光谱学和动力学研究成为可能，而这在羟基型ESIPT体系中以前是无法实现的。在氢键强度（N-H键距离和质子酸度）、ESIPT动力学和热力学之间观察到了经验相关性，表明了一种趋势，即如实验观察到的那样，更强的N-H···N氢键导致更快的ESIPT，以及更放能的反应热力学。因此，在同一系列的氨基型分子内氢键体系中，ESIPT反应首次可以从高度吸能型（即禁止）转变为具有可测量ESIPT速率的平衡态，然后再转变为高度放能且超快的ESIPT反应。
