Syntheses, crystal structure and photophysical properties of [Sm(dbm)3(impy)] and [Tb(dbm)3(impy)] and their hybrid films

Abstract

This paper reports the syntheses, crystal structure and photophysical properties of eight-coordinate complexes [Sm(dbm)₃(impy)] and [Tb(dbm)₃(impy)] (dbm is the anion of 1,3-diphenyl-1,3-propanedione and impy is 2-(1H-imidazol-2-yl)pyridine). The complexes are thoroughly characterized by elemental analysis, FTIR, ESI-MS⁺ and thermal analysis (TGA/DTA). The distorted square antiprismatic structure of the complexes is revealed by single crystal X-ray diffraction analysis. The central metal is coordinatively saturated by six coordinated oxygen atoms of three dbm units and pyridyl and imidazolyl nitrogen atoms of impy. The steady-state and time resolved photoluminescence of the solid complexes and their PMMA hybrid films are investigated and discussed. The decay time of Sm(III) samples is fitted by a mono-exponential function while that of Tb(III) is fitted by a bi-exponential function. The CIE chromaticity of the solid [Sm(dbm)₃(impy)] and its hybrid films does not show any significant change in colour and a light red colour is emitted by both. The CIE chromaticity of [Tb(dbm)₃(impy)] indicates that the overall emission of the solid and the hybrid films is comprised of a blue contribution. The contribution of the blue colour in the luminescence emerging from the 3% hybrid film (w/w) appears to be minimal due to negligible ligand fluorescence and light green luminescence results. The luminescence from the 1.5% hybrid film is purely blue since ligand fluorescence dominates. The solid and its 6% hybrid film emit a turquoise colour. This colour is slightly more intense in the case of the hybrid film.