New acyclic diaminocarbenes cycloplatinated(II) complexes: synthesis, photophysical properties and cytotoxic activity

Abstract

Among all phosphorescent molecules, cyclometalated platinum(II) complexes have receivedconsiderable attention because of their photophysical properties and potential applications asdopants in OLEDs, LECs, photocatalysts or bioimaging. Another research of relevant interest istheir employment as anticancer drugs with a broader spectrum of action against differenttumours and fewer side effects than the well-known cisplatin. For that reason, the choice of thecyclometalated group and ancillary ligands play an important role not only in emissive behaviorbut also on the biological activity.1N-acyclic diaminocarbenes (ADCs) show several appealing characteristics; they display strongelectron-donating ability with structural flexibility and can be easily prepared. However, thereare only a few examples of ADC-platinum complexes used as perspective metal-based drugs inthe literature.2In this contribution, we describe a series of new luminescent ADC cycloplatinated(II) compoundsfeaturing 2-(2,4-difluorophenyl)pyridine (3) and 2-phenylquinoline (4) cyclometalated groups[Pt(C^N)Cl{C(NHXyl)(NHR)}] (R = Pr a, Benzyl b) obtained by nucleophilic addition of primarypropyl and benzyl amines, to the isocyanide ligand of the corresponding precursors[Pt(C^N)Cl(CNXyl)] (1, 2) recently reported by our group.3 Their optical properties haveexamined and interpreted with the aid of DFT/TD-DFT calculations and, finally, all newcompounds have been screened for their cytotoxic activity against various cancer cell lines.