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 ob...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.展开更多
基金supported by the Educational Commission of Anhui Province of China (No.KJ2018A0491)financial support of Anhui Natural Science Foundation (No.1908085MB50)
文摘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.
