Kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of amines and polymethylbenzenes

Abstract

A study of the kinetics of photoreduction of 9,10 phenanthrenequinone in the presence of hydrogen donors (para substituted N,N dimethylanilines and polymethylbenzenes) showed that plots of the quantum yield of photoreduction (ϕ H ) and apparent reaction rate constant (k H ) vs. oxidation potential of hydrogen donors are extreme. In the presence of amines, k H and ϕ H increase, as a whole, whereas they decrease in the presence of polymethylbenzenes. In coordinates ϕ H -∆G e (∆G e is the change in the free energy of electron transfer) for pairs quinone-H donor, ϕ H increases with ∆G e approaching to zero. For the amine series, this effect is mainly in the exothermic region of ∆G e (∆G e < 0). For the series of polymethylbenzenes, this increase is observed in the endothermic region (∆G e > 0).