Syntheses, crystal structures and photoluminescence properties of iridium(III) complexes containing 2-(2’,4’-difluorophenyl)-5-nitropyridine

By using 2-chloro-5-nitropyridine and 2,4-difluorophenylboric acid as starting reagents, 2-(2’ ,4’ - Difluorophenyl)-5-nitropyridine (HdFNppy) has been synthesized through Suzuki coupling reaction and unambiguously characterized. Two iridium(III) complexes [Ir(dFNppy)₂(pic)] (1, pic =picolinate) and [Ir(dFNppy)₂(PPh₃)CI] (2, PPh₃=triphenylphosphine) containing dFNppy main ligand and bi-, mono-dentate ancillary ligands have been prepared and their crystal structures have also been determined by X-ray analysis. 1 crystallizes in monoclinic with space group of 12/a and 2 in triclinic with space group of A1. The photoluminescence (PL) spectra of 1 and 2 in CH₂Cl₂solutions show the emission maxima at 634 and 616 nm, corresponding to red and orange red light-emitting. The emission maxima of 1 and 2 in solid state PL spectra are 638 and 594 nm, respectively. The HOMO-LUMO electronic energy gaps of 1 and 2 estimated from the CV measurements are comparable to those calculated from the UV-Vis spectra of 1 and 2.1 and 2 have remarkable thermal stabilities.