Ring-Closure and Isomerization Capabilities of Spiropyran-Derived Merocyanine Isomers
Ring-Closure and Isomerization Capabilities of Spiropyran-Derived Merocyanine Isomers
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DOI：
10.1021/jp108322u
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发表时间：
2011-04-28
影响因子：
2.9
通讯作者：
Brixner, Tobias
中科院分区：
文献类型：
--
作者：
Buback, Johannes;Nuernberger, Patrick;Brixner, Tobias
本文报道了一种双向光开关螺吡喃化合物6，8-二硝基-1 '，3'，3 '-三甲基螺[2 H-1-苯并吡喃-2，2'-吲哚啉]（6，8-dinitro BIPS）的两种开环异构体TTC和TTT的光化学反应。这两种异构体能够环封闭后，与可见的飞秒激光脉冲激发，所公开的泵浦波长相关的瞬态吸收实验在可见光谱范围内。主要异构体TTC在560 nm处具有其最大吸收，而次要异构体TTT红移（600 nm）。激发态寿命差异很大（TTT的τ近似为900 Ps，TTC的τ近似为95 ps），但ping闭合的量子效率（TTC为40%，TTT为35%）和异构化。(1-2 TTC为1-2%，TTT为1-2%。关于双向光开关能力，6，8-二硝基BIPS是第一个基于6 π-电环化反应的分子开关，其中两个开环异构体都能够闭环。
We report the photochemistry of two ring-open isomers, namely TTC and TTT, of a bidirectional photoswitchable spiropyran, 6,8-dinitro-1',3',3'-trimethylspiro [2H-1-benzopyran-2,2'-indoline] (6,8-dinitro BIPS). Both isomers are capable of ring closure after excitation with visible fs laser pulses, as disclosed by pump-wavelength-dependent transient absorption experiments in the visible spectral range. The main isomer TTC has its maximum absorption at 560 nm, whereas the minor isomer TTT is red-shifted (600 nm). The excited-state lifetimes differ strongly (tau approximate to 900 Ps for TTT and tau approximate to 95 ps for TTC), nevertheless the quantum efficiencies for ping closure (40% for TTC and 35% for TTT) and isomerization.(1-2% for TTC and 1-2% far TTT) are comparable. With regard to the bidirectional photoswitching capabilities, 6,8-dinitro BIPS is the first molecular switch based on a 6 pi-electrocyclic reaction where both ring-open isomers are capable of ring closure.