Influence of platinum metals on spectral and electrochemical characteristics of metallated azole luminophors

Abstract

Spectral (¹H NMR and IR), optical, and voltammetry parameters of Pd(II), Pt(II), Rh(III), and Ir(III) complexes with ethylenediamine and metallated azole luminophors [2-phenylbenzoxazole, 2-phenylbenzothiazole, 2,5-diphenyloxazole, 2-(1,1'-biphenyl)-4-yl]-5-phenyloxazole, and 2-(naphthalene-l-yl)benzothiazole] have been studied. The variation in spectroscopic parameters of the complexes is related to the increase in the efficiency of donor-acceptor interaction of Pt(II) and Ir(III) with the ligands as compared to Pd(II) and Rh(III). The correlation between the energy of the metal-ligand charge transfer bands and the difference between the single-electron oxidation and reduction potentials of the complexes is observed. Quenching of the fluorescence of metallated azoles and phosphorescence of the complexes in the visible region from the metal-modified intraligand excited state are related with the increase in the efficiency of the singlettriplet conversion due to the spin-orbital interaction in platinum metals.