Photodynamic therapy (PDT) is a promising and minimally invasive method for the treatment of superficial diseases, and photosensitizers with high phototoxicity indices (defined as (IC )/(IC )) are essential for the development of ideal photosensitizing properties for this technology. Herein, we report a series of photocytotoxic copper(II) complexes [Cu( QYMP)(dppn)] ( QYMP=N,N,O-tridentate Schiff-base derivatives, dppn=benzo[i]dipyrido[3,2-a;2',3'-c]phenazine), the structures of which have been confirmed by mass spectrometry and FTIR spectroscopy. X-ray crystallography revealed that the CuN O core of the [Cu( QYMP)(dppn)](ClO ) complex (3) has a distorted square-pyramidal geometry. Phototoxicity indices of 329 against human squamous cell carcinoma (SCC15) and 296 against basal cell carcinoma (BCC) cell lines have been determined with [Cu( QYMP)(dppn)](ClO ) (4). This can be attributed to the formation of reactive oxygen species, cell apoptosis, and caspase-3 activation, indicating high potential of complex 4 as a photosensitizer candidate in PDT. Thus, copper complexes bearing suitable Schiff-base ligands with a dppn co-ligand may be considered for the design of efficient metal-based anticancer agents for PDT.
A series of heteroleptic copper(II) complexes [Cu( R QYMP)(Py]] (1a-4d) supported on NNO-tridentate Schiff base ( R QYMP-H) and bipyridine (Py = bpy, a; phen, b; dpq, c; dppz, d) co-ligands have been synthesized and characterized. X-ray crystal structural studies of complexes 1b, 2c, 3d and 4a display that these complexes are mononuclear with a distorted square pyramidal geometry around the copper center.Cytotoxicity results indicate that all of these complexes have much higher activity against HeLa, SCC15, BCC and Ca9-22 cancer cell lines as compared to cisplatin. Further, copper complex bearing suitable bulky group Schiff base ligands with dppz co-ligand could be considered in designing efficient metalbased anticancer agents.
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