LAUSR

Abstract Two novel mononuclear heteroleptic Cu(I) complexes based on mixed phosphine/thiocarbamoyl-pyrazoline ligands were synthesized and structurally characterized. For both complexes, similar structural behavior was observed around Cu(I) atoms, which exhibited a distorted tetrahedral coordination geometry identified using τ4 parameter analysis. Interesting photophysical properties, including strong absorption in the UV–Vis spectral range (200–450 nm) and orange-red emission, were observed in the solid state upon excitation of the prepared compounds at λex = 290 nm. As shown by TD-DFT studies, the absorption and emission behavior of the Cu(I) complexes proved primarily related to HOMO and HOMO−1 to LUMO ((M+X)LCT Cu(d10) → π∗(S C N)) transitions. Complete characterization of the compounds also included X-ray studies, elemental analysis, IR spectroscopy, cyclic voltammetry, and absorption/emission investigation.