Formation of p-terphenyl excited states in the ionic liquid methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide: pulse radiolysis study

摘要

Solutions of 80 mM benzophenone (BP) and up to 14 mM p-terphenyl (TP) in the ionic liquid methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide (R₄NNTf₂) have been investigated by nanosecond pulse radiolysis. The resulting transient absorption spectra of pulse-irradiated argon saturated solutions correspond to the formation of several intermediates derived from BP and TP: benzophenone radical anion [(C₆H₅)₂CO]•− (BP•−) converted after ~20 μs into ketyl radicals (C₆H₅)₂C•OH (BP•H), a hydrogen adduct to the phenyl ring of benzophenone C₆H₅COC₆H₆•, p-terphenyl triplet excited state 3TP*, and traces of TP radical ions. 3TP* was formed in two steps, the first immediately during the pulse and the second in pseudo-first order process with a second order reaction rate constant calculated from TP concentration dependence: k = ~2 × 108 dm3 mol−1 s−1.