The effect of pressure and freezing on luminescence. II. Re(I) metal complexes

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Abstract
The effect of pressure and freezing on the radiative and nonradiative rates from the excited states of two rhenium metal complexes has been investigated in a series of solvents with varying polarity. The radiative rates (k r) depend on the low frequency dielectric constant (ε) of the solvent. A clear demonstration of this dependence is exhibited at the phase transition of the solvent. In polar solvents,k r and ε drop discontinuously while in nonpolar solventsk r and ε show no substantial change. The nonradiative rates (k nr) in the liquid and solid phases, depend primarily on the energy gap between the emitting and ground states. The blue shift in energy causes a drop in k nr. At the phase transition, both the blue shift in peak energy and the narrowing in ground state potential well affect k nr.