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Intramolecular charge transfer in coumarin based donor-acceptor systems: Formation of a new product through planar intermediate

Paper ID Volume ID Publish Year Pages File Format Full-Text
25848 43891 2015 13 PDF Available
Title
Intramolecular charge transfer in coumarin based donor-acceptor systems: Formation of a new product through planar intermediate
Abstract

•Photophysical behavior and ICT of anil derivatives of coumarinyl amine were studied.•Multi-parametric regression analysis shows the importance hydrogen bonding (HB).•HB formation with solvent coupled with ICT leads to the formation of a new isomer.•This process goes through a planar intermediate and instantaneous in S1 state.•However, in the ground state, it involves a barrier height ∼50 kJ mol−1.

Fluorescence behavior and intramolecular charge transfer (ICT) property of N,N′-dimethylamino substituted anil derivative of coumarinyl amine was studied by steady state and time-resolved fluorescence spectroscopy in combination with density functional theory calculation. Quantitative analysis of the effect of solvent hydrogen bonding on several spectral parameters was done using multiple regression analysis based on Kamlet–Taft model. The present system shows an additional long wavelength fluorescence band almost instantaneously in presence of methanol in sharp contrast to the model unsubstituted analogue. This new fluorescence band is believed to be due to the formation of a new isomer (cis-type) through a planar intermediate. While there is a substantial barrier (∼50 kJ mol−1) in the ground state, the isomerization process in the excited state in polar-protic environment proceeds very fast and believed to be catalyzed by hydrogen bond formation at the imine nitrogen atom in combination with stabilization of the resulting species through ICT.

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Keywords
Coumarin fluorescence; Intramolecular charge transfer; DFT calculation; Solvent hydrogen bonding; Photochromic reaction
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Intramolecular charge transfer in coumarin based donor-acceptor systems: Formation of a new product through planar intermediate
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volumes 303–304, 15 April–1 May 2015, Pages 67–79
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Price was $35.95
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