Excited-State Intramolecular Proton Transfer Molecules Bearing o-Hydroxy Analogues of Green Fluorescent Protein Chromophore

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• 作者：Wei-Ti Chuang ; Cheng-Chih Hsieh ; Chin-Hung Lai ; Cheng-Hsuan Lai ; Chun-Wei Shih ; Kew-Yu Chen ; Wen-Yi Hung ; Yu-Hsiang Hsu ; Pi-Tai Chou
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：October 21, 2011
• 年：2011
• 卷：76
• 期：20
• 页码：8189-8202
• 全文大小：609K
• 年卷期：v.76,no.20(October 21, 2011)
• ISSN：1520-6904

文摘

o-Hydroxy analogues, 1a鈥?b>g, of the green fluorescent protein chromophore have been synthesized. Their structures and electronic properties were investigated by X-ray single-crystal analyses, electrochemistry, and luminescence properties. In solid and nonpolar solvents 1a鈥?b>g exist mainly as Z conformers that possess a seven-membered-ring hydrogen bond and undergo excited-state intramolecular proton transfer (ESIPT) reactions, resulting in a proton-transfer tautomer emission. Fluorescence upconversion dynamics have revealed a coherent type of ESIPT, followed by a fast vibrational/solvent relaxation (<1 ps) to a twisted (regarding exo-C(5)鈥揅(4)鈥揅(3) bonds) conformation, from which a fast population decay of a few to several tens of picoseconds was resolved in cyclohexane. Accordingly, the proton-transfer tautomer emission intensity is moderate (0.08 in 1e) to weak (10^鈥? in 1a) in cyclohexane. The stronger intramolecular hydrogen bonding in 1g suppresses the rotation of the aryl鈥揳lkene bond, resulting in a high yield of tautomer emission (桅_f 鈮?0.2). In the solid state, due to the inhibition of exo-C(5)鈥揅(4)鈥揅(3) rotation, intense tautomer emission with a quantum yield of 0.1鈥?.9 was obtained for 1a鈥?b>g. Depending on the electronic donor or acceptor strength of the substituent in either the HOMO or LUMO site, a broad tuning range of the emission from 560 (1g) to 670 nm (1a) has been achieved.