Phosphorescent 2-phenylbenzothiazole Pt IV bis-cyclometalated complexes with phenanthroline-based ligands.

We describe a family of dicationic heteroleptic complexes of the type [Pt(pbt) 2 (N^N)]Q 2 , bearing two cyclometalating 2-phenylbenzothiazole (pbt) groups and a N^N phenanthroline-based ligand [N^N = 1,10-phenanthroline (phen) 4, pyrazino[2,3- f ][1,10]-phenanthroline (pyraphen) 5, 5-amine-1,10-phenanthroline (NH 2 -phen) 6], with two different counteranions (Q = CF 3 CO 2 and PF 6 ). Complexes 4-6-PF6 and 4-6-CF3CO2 were obtained through ligand substitution from cis -[Pt(pbt) 2 Cl 2 ] 2 and cis -[Pt(pbt) 2 (OCOF 3 ) 2 ] 3, respectively. The molecular structures of 2, 3 and 4-PF6 and the photophysical and electrochemical properties of all complexes were studied in detail. The precursors 2 and 3 exhibit high-energy emissions from 3 IL excited states centered on the cyclometalated pbt, with lower efficiency in 2 in relation to 3 by the presence of closer thermally accessible deactivating 3 LMCT excited states in 2. The Pt IV complexes 4-5-CF3CO2/PF6 display orange emission in CH 2 Cl 2 solution, solid state (298, 77 K) or PS films, arising from a 3 IL(pbt) emissive state. The NH 2 -phen derivatives 6-CF3CO2/PF6 show dual emission associated to two close different emissive states, 3 IL'CT (L' = NH 2 -phen) and 3 IL(pbt), depending on the medium and the excitation wavelength. DFT and time-dependent TD-DFT calculations support these assignments and allow explain the luminescence of these tris-chelate Pt IV complexes.