Exploring the luminescent and thermometric potentials of samarium(iii) diketonate complexes with extended fluoroalkyl chains

Abstract

We synthesized and investigated a new series of Sm³⁺ 1,3-diketonate complexes with C_nF_2n+1-homologous thiophene-containing ligands. A clear correlation was found between the number of fluorine atoms in the 1,3-diketone's carbon chain and the luminescent properties of the samarium(III) complexes. The ligand modification method employed facilitates targeted and significant enhancements in the photoluminescence quantum yield (PLQY). Notably, the PLQY value peaked at 5.2% for the complex with n = 4 before decreasing with longer chains, a trend contrasting with that observed for Eu and Nd complexes. Temperature-dependent shifts in the CIE coordinates were observed, making these compounds suitable as luminescent thermometers with a sensitivity of 2.2% K⁻¹ and resolution of 0.2 K at 120 K.