Fluorescence enhancement of rare earth Tb(III) by Tm(III) in benzyl benzoylmethyl sulphoxide complexes

A series of rare earth complexes [(TbxTmy)L5(ClO4)2](ClO4).3H2O (x:y?=?1.000:0.000, 0.999:0.001, 0.995:0.005, 0.990:0.010, 0.950:0.050, 0.900:0.100, 0.800:0.200, 0.700:0.300; L?=?C6H5CH2SOCH2COC6H5) (Tb(III) luminescence ion; Tm(III) doped inert ion) were synthesized and characterized by elemental analysis, infrared spectra (IR) and 1H-NMR. The photophysical properties of these complexes were studied in detail using ultraviolet absorption spectra, fluorescent spectra and lifetimes. The fluorescence spectra of complexes indicated that the fluorescence emission intensity was significantly enhanced by Tm(III). The complexes showed the best luminescence properties when the mole ratio Tb(III):Tm(III) was 0.990:0.010. The fluorescence intensity could be increased to 390%. Additionally, phosphorescence spectra and the luminescence mechanisms are discussed. Copyright (c) 2011 John Wiley & Sons, Ltd.