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QM/MM Studies on Photoisomerization Dynamics of Azobenzene Chromophore Tethered to a DNA Duplex: Local Unpaired Nucleobase Plays a Crucial Role
Author(s) -
Wu Dan,
Wang YaTing,
Fang WeiHai,
Cui Ganglong,
Thiel Walter
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201800006
Subject(s) - photoisomerization , azobenzene , nucleobase , chromophore , chemistry , thymine , molecular dynamics , photochemistry , dna , isomerization , molecule , computational chemistry , catalysis , organic chemistry , biochemistry
The photoresponsive azobenzene‐tethered DNAs have received growing experimental attention because of their potential applications in biotechnology and nanotechnology; however, little is known about the initial photoisomerization of azobenzene in these systems. Herein we have employed quantum mechanics/molecular mechanics (QM/MM) methods to explore the photoisomerization dynamics of an azobenzene‐tethered DNA duplex. We find that in the S 1 state the trans–cis photoisomerization path is much steeper in DNA than in vacuo, which makes the photoisomerization much faster in the DNA environment. This acceleration is primarily caused by complex steric interactions between azobenzene and the nearby unpaired thymine nucleobase, which also change the photoisomerization mechanism of azobenzene in the DNA duplex.