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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/41285

Title: N-H-Type Excited-State Proton Transfer in Compounds Possessing a Seven-Membered-Ring Intramolecular Hydrogen Bond
Authors: Pi-Tai Chou
Fan-Yi Meng
Yi-An Chen
Yen-Hao Hsu
Cheng-Hsien Hung
Chi-Lin Chen
Kun-You Chung
Wei-Feng Tang
Wen-Yi Hung
Contributors: 國立臺灣海洋大學:光電科學研究所
Keywords: thermodynamics
hydrogen bonds
kinetics;proton transfer
Date: 2016
Issue Date: 2017-02-14T01:42:07Z
Publisher: Chemistry
Abstract: Abstract: 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 fine-tuned 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 %.
Relation: 22(4)
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/41285
Appears in Collections:[光電科學研究所] 期刊論文

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