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The synthesis and photolysis mechanisms of 8‐nitroquinoline‐based photolabile caging groups for carboxylic acid
Author(s) -
Sun Fude,
Zhang Lei,
Yan Jianhua,
Xu Lida,
Fang Decai,
Luo ShiZhong
Publication year - 2014
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3385
Subject(s) - chemistry , intersystem crossing , photodissociation , chromophore , photochemistry , carboxylic acid , quantum yield , ground state , potential energy surface , nitro , density functional theory , molecule , computational chemistry , excited state , fluorescence , organic chemistry , physics , alkyl , quantum mechanics , nuclear physics , singlet state
Photolabile protecting groups have been extensively studied and applied for protection of small biological molecules, which make it convenient to detect the biological processes of the caged compounds. In this study, a series of 8‐nitroquinoline‐based photolabile caging groups for carboxylic acid were synthesized with improved photolysis efficiency. Among them, 6‐bromo‐8‐nitro‐1, 2‐dihydroquinolinyl chromophore was proven the best derivative on account of its longest absorption wavelength (345 nm), highest caging ability, and quantum yield ( Φ = 0.003). Moreover, density functional theory calculations were performed in order to study the photolysis mechanisms. Theoretical calculations revealed that the reaction was kinetically inert under general mild condition with the high barrier height of 34.3 kcal/mol at carbonyl migration step, while under the photolysis condition, because of the large energy gap (64.5 kcal/mol) between S 0 and S 1 states, the reaction should be accessible in the triplet ground state ( T 1 ) through successive excitation of S 0 → S 1 states, subsequent intersystem crossing of S 1 → T 1 states, and finally returned to the stable S 0 state for product via potential energy surface crossing between T 1 and S 0 states. Copyright © 2014 John Wiley & Sons, Ltd.