Synthesis and photoluminescence study of two new complexes [Sm (hfaa)3(impy)2] and [Eu(hfaa)3(impy)2] and their PMMA based hybrid films

The synthesis, characterization and photoluminescence studies of two new highly photoluminescent complexes, [Sm(hfaa)(3)(impy)(2)] and [Eu(hfaa)(3)(impy)(2)] (impy is 2-(1H-imidazol-2-yl)pyridine and hfaa is the anion of hexafluoroacetylacetone) are reported. The photoluminescence of these complexes were studied in solid, solution and PMMA thin films. These complexes were incorporated independently into polymer matrix of PMMA with varying amounts. The calculated quantum yield (phi) and experimental life time (tau) in solution for (i) Sm complex are phi=0.013, tau=0.036 ms and (ii) Eu complex are phi=0.36, tau=0.98 ms. The Judd-Ofelt intensity parameters, radiative parameters, intramolecular energy transfer rates and theoretical quantum efficiency are calculated and discussed. The intramolecular energy transfer rates, in the case of europium complex, suggest that the major energy transfer channels are T-1 -> D-5(1) and T-1 -> D-5(0) and these contribute 55.33% and 44.65%, respectively, to the overall energy transfer process. The emission colour changes with a change in concentration of the complexes in PMMA substrate. This feature may be employed in fabricating 'colour indicator diodes'. The thin hybrid films of these structurally ten-coordinate complexes in PMMA matrix exhibit outstanding photostability upon UV irradiation that defines their robust nature. The efficient photophysical properties of PMMA hybrids of these complexes, may possibly find their applications in optoelectronic devices.