pH dependent uorescence emission of a thioxanthone-based probe has been re-ported recently.The potential deter-minant factors of pH dependence may provide important clues to design novel thioxanthone-based probes in t...pH dependent uorescence emission of a thioxanthone-based probe has been re-ported recently.The potential deter-minant factors of pH dependence may provide important clues to design novel thioxanthone-based probes in the fu-ture.pH dependence of photochemical kinetics of thioxanthone itself was inves-tigated in this work using nanosecond time-resolved laser ash photolysis.The nanosecond time-resolved transient absorption spectra and kinetics of TX in aqueous acetonitrile were recorded,as well as for a model reaction system including TX with diphenylamine(DPA)as a co-initiator.Besides the well-known absorption peak of ^(3)TX*,other peaks at 417,518,673 and 780 nm,have been reliably attributed to major intermediates in the overall reaction between TX and DPA with photolysis,which has been con rmed to occur along a multistep process.In the strong acidic solution(pH≈3.0),TX and protonated TX ions(TXH^(+))coexist due to protonated equilibrium.Consequently,high proton concentration promotes the predominant decay pathway after photolysis from electron transfer to proton affnity.Subsequently,the di erent primary products,^(3)TXH^(+*)or TX^(·-),proceed di erent secondary reaction channels.In addition,within the wide pH range from weak acid(pH=5.0)to alkaline solution(pH=13.0),the overall reaction mechanism and rates do not show visible changes.展开更多
基金This work was supported by the Educational Com-mission of Anhui Province of China(No.KJ2018A0491 and KJ2019A0736)the National Natural Science Foun-dation of China(No.21873089)the Natural Science Foundation of Anhui Province(No.1908085MB50).
文摘pH dependent uorescence emission of a thioxanthone-based probe has been re-ported recently.The potential deter-minant factors of pH dependence may provide important clues to design novel thioxanthone-based probes in the fu-ture.pH dependence of photochemical kinetics of thioxanthone itself was inves-tigated in this work using nanosecond time-resolved laser ash photolysis.The nanosecond time-resolved transient absorption spectra and kinetics of TX in aqueous acetonitrile were recorded,as well as for a model reaction system including TX with diphenylamine(DPA)as a co-initiator.Besides the well-known absorption peak of ^(3)TX*,other peaks at 417,518,673 and 780 nm,have been reliably attributed to major intermediates in the overall reaction between TX and DPA with photolysis,which has been con rmed to occur along a multistep process.In the strong acidic solution(pH≈3.0),TX and protonated TX ions(TXH^(+))coexist due to protonated equilibrium.Consequently,high proton concentration promotes the predominant decay pathway after photolysis from electron transfer to proton affnity.Subsequently,the di erent primary products,^(3)TXH^(+*)or TX^(·-),proceed di erent secondary reaction channels.In addition,within the wide pH range from weak acid(pH=5.0)to alkaline solution(pH=13.0),the overall reaction mechanism and rates do not show visible changes.
