Time resolved absorption and emission experiments are combined with quantum chemical calculations to obtain a quantitative understanding of the light-induced Z to E isomerization of the hemithioindigo photoswitch. Substitution and solvent polarity change the Z to E reaction time by three orders of magnitude from 9 ps for the para-methoxy substituted 5-methyl hemithioindigo in the unpolar cyclohexane to 9 ns for the para-cyano substituted molecule in di-chloromethane. A comparison with quantum chemical calculations reveals the role of the solvent polarity on the reaction speed for distinct substitution patterns of the stilbene moiety. The dipole moments of the different hemithioindigo photoswitches strongly vary on the excited state potential energy surface. Energetic stabilization of the minimum and simultaneous destabilization in the transition region increase the effective reaction barrier for polar solvents, thus strongly decelerating the reaction.

将时间分辨的吸收和发射实验与量子化学计算相结合，以获得对半硫靛蓝光开关的光诱导Z到E异构化的定量理解。取代和溶剂极性将Z到E的反应时间改变了三个数量级，从非极性环己烷中的对甲氧基取代的5-甲基半硫靛蓝的9 ps变为二氯甲烷中的对氰基取代的分子的9 ns。与量子化学计算的比较揭示了对于二苯乙烯部分的不同取代模式，溶剂极性对反应速度的作用。不同的半硫靛蓝光开关的偶极矩在激发态势能表面上有很大变化。