摘要
The photophysical and photochemical behaviors of thioxanthen-9-one(TX)in different solvents have been studied using nanosecond transient absorption spectroscopy.A unique absorption of the triplet state^(3)TX^(∗) is observed,which involves two components,^(3)nπ^(∗) and^(3)ππ^(∗) states.The ^(3)ππ^(∗) component contributes more to the^(3)TX^(∗) when increasing the solvent polarity.The self-quenching rate constant ksq of^(3)TX^(∗)is decreased in the order of CH_(3)CN,CH_(3)CN/CH_(3)OH(1:1),and CH_(3)CN/H_(2)O(1:1),which might be caused by the exciplex formed from hydrogen bond interaction.In the presence of diphenylamine(DPA),the quenching of^(3)TX^(∗)happens efficiently via electron transfer,producing the TX^(⋅−) anion and DPA^(⋅+) cation radicals.Because of insignificant solvent effects on the electron transfer,the electron affinity of the ^(3)nπ^(∗) state is proved to be approximately equal to that of the ^(3)ππ^(∗) state.However,a solvent dependence is found in the dynamic decay of TX^(⋅−) anion radical.In the strongly acid aqueous acetonitrile(pH=3.0),a dynamic equilibrium between protonated and unprotonated TX is definitely observed.Once photolysis,^(3)TXH^(+∗) is produced,which contributes to the new band at 520 nm.
基金
supported by the Educational Commission of Anhui Province of China (No.KJ2018A0491)
financial support of Anhui Natural Science Foundation (No.1908085MB50)
