Luminescent Cyclometalated PtIV Compounds with N-Donor Ligands: Synthesis and Study of their Properties

Resumen

Although numerous studies have been carried out on d6 phosphors, such as RuII, OsII or IrIII and d8,particularly PtII, studies on related luminescent PtIV derivatives are scarce1. Our group has recentlypublished two series of neutral bis(cyclometalated)pentafluorophenyl PtIV complexes with Cl- or CN-as auxiliary ligands2. On the other hand, benzothiazole is a versatile platform with applicationsranging from biosensing to optical devices. They have been employed as ligands to form yellowphosphorescent metal complexes and recent studies have also demonstrated promisingantiproliferative activity3.This work focuses on the study of two series of dicationic bis-cyclometalated PtIV compoundsfeaturing 2-phenylbenzothiazolyl groups and selected N,N’-phenantroline-based ligands of formulae[Pt(pbt)2(N^N)]X2 (X = PF6, CF3CO2) (N^N = phen 4, 4'; pyraphen 5, 5'; NH2-phen 6, 6'), using[Pt(pbt)2Cl2] 2 and [Pt(pbt)2(OCOCF3)2] 3 as precursors. All complexes have been fully characterizedby spectroscopic techniques, and the molecular structure of 3 has been confirmed X-ray diffraction.A comparative study of their optoelectronic properties in different media (solid state, solution andpolymeric film for emission) has been carry out. 2 and 3 exhibit emission based on pbt (3IL), whereasthe excited states of phenantroline-based ligands are of mixed 3LL’CT/3IL/3IL’ configuration withremarkable 3IL’ (phen-NH2) ligand contribution. To insight into the nature of the optical properties,theoretical analysis has been carried out at DFT/TD-DFT level for selected complexes (2, 3, 42+ and62+).