Steady-state and time-resolved fluorescence studies of the kinetics and thermodynamics of photoinduced charge-transfer reaction in dicyanobenzene-toluene exciplex

A study of the photokinetics of photoinduced charge-tranfer reaction of electron-donor-acceptor system of 1,4-dicyanobenzene with toluene is reported. An analysis of the results of steady-state and transient measurements of fluorescence of monomer and exciplex within the framework of two-state kinetic scheme has brought about a set of rate constants and thermodynamic parameters pertinent to excited state equilibrium of the system. A position of excited state equilibrium can be relatively easy shifted by changes of temperature (and polarity) of solvent and this is due to sensitivity of thermal feedback dissociation of exciplex to temperature. The relevance of the results to more complicated photokinetic schemes of other weak electron-donor-acceptor systems is also discussed.