Photophysical properties of mono- and di-nuclear platinum(II) complexes with the tridentate ligand 2-phenyl-6-(1H-pyrazol-3-yl)-pyridine: A DFT and TDDFT study

The luminescent cyclometalated platinum(II) complex [Pt(HL)Cl] (1) (where HL = 2-phenyl-6-(1H-pyrazol-3-yl)-pyridine anion) and its deprotonated dimer complex [Pt2(L)2] (2) were theoretically studied via density functional theory (DFT) and time-dependent DFT (TDDFT) in conjunction with the polarizable continuum model (PCM) solvent effect to investigate their molecular geometries (at the S0, S1, and T1 states), electronic structures, and photophysical properties (absorption and phosphorescence spectra) and to elucidate the reason for the significantly higher phosphorescence quantum yield of 2 (59%) compared to that of the 1 (14%).