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Selective photoisomerization of methyl substituted nitro diphenylbutadienes

Paper ID Volume ID Publish Year Pages File Format Full-Text
25884 43907 2014 10 PDF Available
Title
Selective photoisomerization of methyl substituted nitro diphenylbutadienes
Abstract

•4-Nitrodiphenylbutadiene yields no photoproducts upon photoirradiation.•Methyl on butadiene chain promotes isomerization.•The position of isomerization migrates along with the placement of methyl group.

A series of p-nitro substituted trans-diphenylbutadienes is synthesized and their photophysical and photochemical properties are investigated. All the dienes have a very low quantum yield of fluorescence but exhibit remarkable solvatochromic emission shifts attributed to twisted intramolecular charge transfer. Photochemical irradiation of simple p-nitro substituted diphenylbutadienes reveals inefficient or no detectable photoisomerization. However, substituting a methyl group on the butadiene chain of p-nitro substituted diphenylbutadiene or replacing the nitro group with cyano group yields the corresponding trans–cis isomers. In the case of simple nitrodienes, strong intramolecular charge transfer character in the excited state aids dissipation of absorbed energy through non-photochemical and non-radiative channels. The steric effect caused by the presence of methyl group lowers the isomerization barrier in methyl substituted dienes leading to a regioselective isomerization.

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Keywords
Regioselective photoisomerization; Intramolecular charge transfer; Solvatochromism
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 293, 1 November 2014, Pages 40–49
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Full-text PDF Download
Online Support
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