Determination of contributions of various molecular groups to nonradiative deactivation of electronic excitation energy in β-diketonate complexes of ytterbium(III)

Quantum yields and lifetimes of F-2(5/2) --> F-2(7/2) fluorescence are measured for double and heteroligand complexes of ytterbium with dibenzoylmethane and thenoyltrifluoroacetone, as well as their analogs with a deuterated central C-H group dissolved in toluene acid deuterated dimethyl sulfoxide (DMSO-d(0)). Deuteration of beta -diketone is shown to cause a significant increase in the lifetime of Yb3+ fluorescence (up to 72 mus for thenoyltrifluoroacetone in DMSO-d(6)). Based on the experimental data, a system of equations is constructed that makes it possible to determine contributions of various molecular groups of a complex and the external-sphere solvent to nonradiative deactivation of the F-2(5/2) State of ytterbium. Possible ways of producing Yb3+ complexes with improved fluorescent characteristics are discussed. (C) 2001 MAIK "Nauka/Interperiodica".