Correlation between photolysis rate constants of polycyclic aromatic hydrocarbons and frontier molecular orbital energy

In the present study, pseudo-first-order direct photolysis rate constants of 17 PAHs were determined. Basing on the frontier molecular energy, Ehomo and Elumo, a QSPR equation was obtained. The obtained equation can be used to predict photolysis rate constants of PAHs under the irradation of medium pressure mercury lamp. As shown in the following equation, the obtained relationship between the logarithm of photolysis rate constants(logkexp) and Elumo-Ehomo gap was parabolic. logkexp=−32.738+9.770 (Elumo−Ehomo)−0.715(Elumo−Ehomo)2 n=17, r=0.921, SE0.322, F=38.911, p=0.0000 Where r is the multiple correlation coefficient, SE is the standard error of estimates for the full regression, F is the F value for analysis of variance, p is the significance level. The obtained parabolic relationship is reasonable when internal and external factors controlling photolysis rate are considered.