Luminescent iridium(III) complexes with nitrogen-rich 1,2,3-triazoles: Synthesis, photophysics and electrochemistry

Nitrogen-rich metal complexes, which feature nitrogen-containing heterocycles with two or more N–N and C–N bonds, offer flexible coordination modes and notable structural stability. This study presents a straightforward synthesis of luminescent nitrogen-rich iridium(III) complexes (NRIr1–NRIr4) utilizing click chemistry-derived triazole chelates. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has been utilized to synthesize triazole-based cyclometalated ligands (L1–L4), and imidazole-functionalized bipyridine ligand served as ancillary ligand (AnL). Comprehensive structural characterization through single-crystal X-ray diffraction and DFT calculation reveals a slightly distorted octahedral geometry around the iridium center. The photophysical studies show emission maxima ranging from 533 nm to 565 nm, with quantum yields varying from 0.1% to 7.2%. Electrochemical analysis reveals irreversible metal-based oxidation peaks with potentials around 1.30 V and reduction potentials from −1.14 V to −1.19 V. These results highlight the impact of nitrogen-rich ligands on the electronic properties of the iridium center, leading to enhanced luminescent performance and efficient energy transfer.