Phosphorescence properties and bioimaging of pyridine auxiliary ligand cyclometalated Pt(II) complex with multiphoton absorption

We synthesized the cyclometalated Pt(II) complex (Pt-Lyb) modified by a pyridine auxiliary ligand with electron delocalization capability. The introduction of pyridine ethylene ligand increases the conjugate structure of the system, and the heavy atom effect of the Pt(II) complex can effectively promote the intersystem crossing (ISC) between the singlet and triplet states of the Pt(II) complex. Viscosity test results revealed that the two-photon and three-photon absorption activities were enhanced with the increase in viscosity. Besides, it was found that Pt-Lyb had a better inhibitory effect on cancer cells and a stronger ability to target subcellular organelles (cell membranes) than cisplatin. This indicates that the platinum complexes have potential application prospects in bioimaging.