Syntheses, crystal structures and photophysical properties of d10 transition-metal (Ag+, Cu+, Cd2+ and Zn2+) coordination complexes based on a thiophene-containing heterocyclic thioamide
Four d10 transition-metal coordination complexes 1–4 (1: [Ag2(TPT)2(TPTH)2]; 2: [Cu6(TPT)6]·2DMF; 3: [Cd(TPT)2(TPTH)]·CH3CH2OH, 4: [Zn(TPT)2]n) have been constructed from a newly designed heterocyclic thioamide ligand, TPTH (TPTH = 4-(thiophen-2-yl)-pyrimidine-2-thiol). All complexes have been structurally elucidated by single crystal X-ray diffraction analyses. Except for 4, which shows a one-dimensional (1-D) chain structure, 1–3 are all discrete coordination complexes featuring dinuclear, hexanuclear and mononuclear entities, respectively. Their photophysical properties have been evaluated in the solid state at room temperature by UV–vis diffuse reflectance and luminescence spectra. Among them, 2 exhibits a strong red luminescence (λem = 699 nm) with a remarkable red-shift of the maximum emission compared to that of the TPTH ligand (λem = 536 nm). The red emission observed with 2 is ascribed to a LMCT (ligand-to-metal charge transfer) transition which agrees with the DFT calculations.