Solvent effects on isomerization and spectral properties of photochromic-switching diarythene derivatives in polar and apolar solutions.
Solvent effects on isomerization and spectral properties of photochromic-switching diarythene derivatives in polar and apolar solutions.
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DOI：
10.1021/jp210846b
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发表时间：
2012-01
期刊：
影响因子：
--
通讯作者：
S. Meng;Jing Ma
中科院分区：
文献类型：
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作者：
S. Meng;Jing Ma
用密度泛函理论(DFT)和分子动力学(MD)方法研究了二芳基衍生物在溶液中的光致变色开关的光环化行为和动态构象转变。1，2-二(2-甲基苯并-3-基)顺丁烯二酸酐的开环异构体有三种可能的构象：反平行(反)、平行(对)和扭曲。PCM-B3LYP/6-31G*计算和分子动力学模拟都表明，在室温下，反扭曲开环异构体可以在正己烷和乙腈溶液中自由相互转化。分子动力学模拟得到正己烷和CH(3)CN的扭转比分别为2.09和1.07，与Arrhenius的DFT活化能计算结果(正己烷1.18和CH(3)CN)定性一致。溶剂极性对基态开环异构体异构化反应影响不大。由于激发时有明显的电荷转移，溶剂对低激发态(S(1)和S(2))的电子结构和吸收光谱的影响更为显著。对于这种电荷转移激发态，长程修正的泛函CAM-B3LYP比B3LYP能更好地符合实验光谱。溶剂的极性和电荷转移激发态的极化是制备新型功能化光致变色分子开关的关键。
The photocyclization behavior and dynamic conformational transition of photochromic switches of diarythene derivatives in solutions are investigated by using the density functional theory (DFT) and molecular dynamics (MD) simulations. Three possible conformations, antiparallel (anti), parallel (para), and twist, for the open-ring isomers of 1,2-bis(2-methylbenzothiophene-3-yl)maleic anhydride are located. Both PCM-B3LYP/6-31G* calculations and MD simulations demonstrate that anti and twist open-ring isomers can interconvert freely in n-hexane and acetonitrile solutions at room temperature. The statistical ratio of twist to anti isomers from MD simulations is 2.09 in n-hexane and 1.07 in CH(3)CN, in qualitative agreement with those (1.18 in n-hexane and 1.05 in CH(3)CN) estimated from Arrhenius analysis of DFT activation energies. The solvent polarity has little influence on the isomerization of open-ring isomers in the ground state. Due to the evident charge transfer upon excitations, the solvent effects on the electronic structures and absorption spectra of low-lying excited states (S(1) and S(2)) are more significant. For such charge-transfer excited states, the long-range corrected functional CAM-B3LYP gives better agreement with the experimental spectra than B3LYP. The solvent polarity and polarization of the charge-transfer excited states are crucial for fabricating the novel functionalized photochromic molecular switches.