Synthesis, Structure, Optical, and Electrochemical Properties of the Chromophore Cyclometalated Iridium(III) Complex

A new N-donor ligand, methyl 4-(1-methyl-1H-perimidin-2-yl)nicotinate, and the corresponding octahedral cationic iridium(III) complex (I) were designed and synthesized. 1-Benzyl-2-phenyl[2,3]naphthimidazole was used as a cyclometalated ligand; PF served as a counterion. Compound I was characterized by H, C, F, P, H,H-COSY, H,H-NOESY NMR, high-resolution mass spectrometry and X-ray diffraction. As a result of the combination of ligands containing a large conjugated system around the metal ion, the target complex exhibits light absorption up to 700 nm (ε ~ 1000 M·cm), translating in its deep color. Complex I demonstrates reversible electrochemical behavior at positive potentials with E = 0.58 V vs. E. In terms of the key characteristics, the resulting compound surpasses most iridium analogs, and therefore appears promising for further testing in photovoltaic devices.