Phenylbenzothiazole Bis(Cyclometalated) Pt(IV) Complexes With Phenanthroline‐Based Ligands as ROS, NADH and Microtubule Destabilizing Agents

Pt(IV) complexes have garnered extensive attention in relation to their optical properties and biological activity. Herein, we report a new series of luminescent cationic cyclometalated Pt(IV) complexes with phenanthroline‐type ligands [Pt(pbt) 2 (N^N)](ClO 4 ) 2 (pbt = phenylbenzothiazole; N^N = phen 2 , pyraphen 3 , NH 2 ‐phen 4 ), obtained from [Pt(pbt) 2 Cl 2 ] ( 1 ), and their biological activity. Complexes 2 and 3 showed orange emissions, attributed to a 3 IL (pbt) excited state, whereas complex 4 showed dual emission arising from closely lying 3 IL′CT/ 3 L′LCT (L′ = NH 2 ‐phen) states, as confirmed by DFT calculations. Upon blue light irradiation, complexes 1 and 4 generated 1 O 2 and catalyzed NADH photooxidation. Spectroscopic studies indicated BSA binding for complexes 2 and 4 . Among the series, complex 4 exhibited the highest anticancer cytotoxic activity, comparable to cisplatin, and 1 – 3 showed mild phototoxicity. Complex 4 generated intracellular ROS production, microtubule depolymerization and mitochondrial damage in A549 cells, without DNA interaction.