Synthesis and Characterization of an Ir(III) Complex with Potential Application for BSA Detection

Ir(III) complexes have attracted significant interest due to their remarkable photophysical properties, arising from ligand-centered (LC) and metal-to-ligand charge-transfer (MLCT) excited states, which enable applications in optoelectronics, photodynamic therapy, and chemical sensing. In this work, the new complex K[Ir(Fppy)₂(bqdc)] (Fppy = 2-(2,4-difluorophenyl)pyridine; bqdc = 2,2′-biquinoline-4,4′-dicarboxylic acid) was synthesized with an 80% yield and characterized by FTIR, Micro-TOF MS, and multinuclear NMR, confirming its proposed structure. UV–Vis spectroscopy revealed a ligand-centered absorption band at 270 nm, while the complex displayed broad orange-red emission centered at 600 nm. Under acidic conditions (pH 2.5), its luminescence was quenched but restored upon addition of bovine serum albumin (BSA), demonstrating a turn-on sensing response. Preliminary results indicate a detection limit of 2.4 mg L⁻¹ BSA, highlighting the potential of this complex as a luminescent BSA sensor in solution.