The excited singlet state quenching of organic hydrocarbons by
Co(III) and Cr(III) βdiketonate complexes have been investigated using
the technique of single photon counting. It is established that the most
likely quenching mechanism is that of electronic energy transfer.
The observed rate constants for the quenching of naphthalene and
pyrene by Cr(acac)3 in a series of solvents are shown to be consistent with the
predictions made for a dipole-dipole mechanism coupled with molecular diffusion.
In addition it has been possible to demonstrate the breakdown of the Stokes-Einstein
equation in the determination of the diffusion coefficients required in
the calculations for hydroxylic solvent systems. The importance of exchange
contributions in the less efficiently quenched pyrene systems is also discussed [continued]…
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.