Synthesis, structures, properties, and chemical-sensor application of iridium(III) bis-cyclometallated complexes with two pyridine-derived ligands

Treatment of cis-[Ir(η2-ppy)2(MeCN)2]NO3 (1, ppy = 2-phenylpyridine) with isonicotinaldehyde, ethyl isonicotinate, and 4-aminopyridine afforded cis-[Ir(η2-ppy)2L2]NO3 (L = 4-pyCHO (2), 4-pyCOOEt (3), 4-pyNH2 (4)). The photophysical properties of these complexes were determined. Complex 4 is a good light-emitting chemical sensor toward silver trifluoromethanesulfonate in methanol. Crystal structures of 2 and 3 as well as that of the adduct, formed between 4 and AgNO3, have been characterized by X-ray diffraction.