Photodynamic therapy(PDT)has thrived as a promising cancer treatment modality in recent years1.Herein,four trinuclear platinum–triphenylamine isomers were synthesized to investigate their potential as PDT anticancer agents.The results found that when platinum(Ⅱ)moieties were conjugated to the paraposition of the pyridyl ring of the triphenylamine core(complexes 1 and 2),they exhibited much better PDT activities than their meta-position coordinated counterparts(complexes 3 and 4),owing to the redder absorption and emission wavelength,higher singlet oxygen quantum yield and cell nucleus-targeted ability2.Further studies revealed that complex 2,which was the most potent among the four complexes,effectively induced DNA damage responses,arrested the cell cycle in the G2/M phase and consequently resulted in cancer cell apoptosis upon 425 nm light irradiation(40 mW cm-2,15 min).In vivo studies also demonstrated that 2 was an effective photodynamic anticancer agent.