Solvent effect on the physical quenching of singlet molecular oxygen by p-quinones

摘要

Rate constants for the interaction between singlet molecular oxygenO2(~1DELTA_g)and the p-quinones 1,4-benzoquinone(BQ),duroquinone(DQ),9,10-anthraquinone(AQ)and l,8-dihydroxy-9,10-anthraquinone(OHAQ)are reported for several solvents at room temperature.The solvent effect on the total quenching rate constant(k_t)was analysed employing the semiempirical solvatochromic equation proposed by Kamlet and Taft.The higher values of k_t(2-7X10~7 M~(-1)s~(-1))were obtained when the hydrogen-bond donor solvent ability is increased(higher a parameter values).The results indicate the importance of specific solvent interactions in governing the rates of the quenching.