Aggregation Induced Emission Active Organoiridium(III) Complex Based on Piperazine‐Substituted 1,10‐phenanthroline Ligand as pH‐Responsive Probe

ABSTRACT In this work, the rational design and synthesis of a new green emissive cyclometalated iridium(III) complex‐based AIEgen 1[PF 6 ] containing a piperazine‐substituted 1,10‐phenanthroline ligand is presented. 1[PF 6 ] was fully characterized by NMR spectroscopic and ESI‐MS spectrometric studies. The photophysical properties of 1[PF 6 ] were examined by UV‐vis and PL spectroscopic studies. The electronic transitions associated with the absorption and emission spectra of 1[PF 6 ] in acetonitrile were predicted using standard computational methods. While 1[PF 6 ] was weakly emissive in acetonitrile, a significantly enhanced emissive pattern was observed in water and polyethylene glycol (PEG), indicating the aggregation‐induced emission (AIE) phenomenon. The formation of aggregated particles from 1[PF 6 ] was evidenced by UV‐vis spectroscopy, DLS, SEM, and TEM studies. Interestingly, the pH‐responsive modulation of the luminescence intensity of 1[PF 6 ] in the aqueous medium, as well as in the fabricated portable paper strips, highlighted a higher emission profile in the slightly acidic medium (pH: 3–5) with a reduced emission intensity pattern towards the neutral to alkaline medium. Moreover, the biocompatibility of 1[PF 6 ] was assessed in a representative cervical cancer cell line (HeLa) with intense green emission and a low cytotoxicity profile, indicating the potential real‐time application of 1[PF 6 ] as a pH‐responsive AIEgen in the future.