RESUMO
The transient photochemical behavior of xanthone (XAN) in 1-butyl-3-methyl imidazolium hexafluoride phosphate ionic liquid ([bmim][PF6]) or binary mixed solution with acetonitrile (MeCN) was investigated by nano-second laser photolysis techniques. The spectral blue shift of 3XAN* was observed in the neat [bmim][PF6] or IL/MeCN mixture solution compared to MeCN solution. And the yield was also increased. Moreover, the energy transfer rate constant of XAN and naphthalene (NAP) was affected by the concentrations of ionic liquid. The values decreased rapidly with increasing VIL. For example, the values were 1.2 x 10(10) mol x L(-1) x s(-1) in MeCN, and 1.1 x 10(8) mol x L(-1) x s(-1) in [bmim][PF6], respectively. The photo-induced electron transfer between XAN and N,N-dimethylaniline was also investigated by changing the concentrations of [bmim][PF6] in binary solution.
RESUMO
The photochemistry of pyrene in conventional solvents (acetone, acetonitrile, cyclohexane) and ionic liquids [Bmim] [PF6], [BuPy][BF4], R4 NNTf2 was investigated by time-resolved laser photolytic techniques. The transient absorption spectra of the excited pyrene and other radical species were compared. The absorption band of pyrene cation radical was observed in the acetone, acetronitrile and pyridinium ionic liquid [BuPy][BF4] systems. Only excited triplet pyrene was observed in cyclohexane and [Bmim][PF6] and R4 NNTf2. The result demonstrates that there was an interaction between pyrene and solvents, and the pyrene cation radical was formed by electron transfer from the excited state of pyrene to acetonitrile, acetone and [BuPy][BF4]. The possible mechanisms of the six systems were suggested.
