Cationic Platinum(II) Complexes Bearing Aryl-BIAN Ligands: Synthesis and Structural and Optoelectronic Characterization

Five cationic platinum(II) complexes bearing a 2-(3′-substituted aryl)pyridine cyclometalating ligand (C ∧ N) and a neutral Ar-BIAN ligand have been synthesized: [Pt(ppy)(PhBIAN)]PF 6 ( 1 ), [Pt(3Fppy)(PhBIAN)]PF 6 ( 2 ), [Pt(3MeOppy)(PhBIAN)]PF 6 ( 3 ), [Pt(3MeOppy)(4-FPhBIAN)]PF 6 ( 4 ), [Pt(ppy)(4-MeOPhBIAN)]PF 6 ( 5 ). All complexes have been characterized by NMR spectroscopy and mass spectrometry. Complexes 2 and 3 have been characterized by X-ray crystallography. Structure–property relationships were established from UV–visible spectroscopy and cyclic voltammetry studies. Interestingly, we found that when both the C ∧ N and the Aryl-BIAN ligands contained electron-donating MeO groups the absorption spectrum for the platinum complex extended out to 650 nm. The electrochemical studies of these complexes established that they are electronically compatible dye molecules for dye-sensitized solar cells.