Abstract

A series of hybrid organo-inorganic mononuclear lanthanoid complexes, [n-NBu4](3)[LnH(PW11O39) (phen)(2)].H2O, denoted as LM4-1-Ln (Ln = Dy-III, Tb-III, Eu-III, Nd-III, Er-III, Ho-III and Gd-III), were synthesized via hydrothermal synthesis and were structurally characterized by X-ray diffraction. The optical properties of all complexes have been investigated in the solid state. The temperature-dependent emission spectra of LM4-1-Dy, LM4-1-Tb and LM4-1-Eu complexes show intense lanthanoid emissions in the visible region, while LM4-1-Nd shows near-infrared (NIR) luminescence. The Eu-III complex shows typical strong red emissions from the D-5(0) -> F-7(0,1,2,3,4) transitions, with the CIE colour coordinates (0.631,0.364), the colour purity value of 83.9% and a quantum yield of up to 4.3%, suggesting that the organic fragment has an effect on the optical properties compared to fully inorganic systems, making this complex very attractive as a red component of light-emitting diodes. The luminescence decays of LM4-1-Dy, LM4-1-Tb and LM4-1-Eu exhibit a biexponential behaviour, with tAV = 4.1(7) mu s, 0.35(2) ms and 0.94(3) ms, respectively. The values obtained for Judd-Ofelt intensity parameters O-2 and O-4 support the interaction between the Eu-III and the ligands. Furthermore, those with Er-III and Ho-III present weak emissions in the visible region. The T-dependent photoluminescence results show that the LM4-1-Dy, LM4-1-Tb and LM4-1-Nd complexes have good temperature sensitivity, demonstrating that the materials have the potential to be used as a sensing element for luminescent thermometers in different temperature ranges.