Impact of the Aliphatic Dicarboxylate Chain of Novel Dinuclear Palladium(II) Complexes: Synthesis and Biological Evaluation

Abstract Five dinuclear palladium(II) complexes with HOOC(CH 2 ) n COOH ( n =2–6) and 2,2′‐bipyridine ligands were synthesigned by a reaction with K 2 PdCl 4 . To prepare such complexes with different aliphatic dicarboxylate chain lengths was in an attempt to correlate this length factor, which influences the biological activity of the complexes, with fluorescence spectra, DNA cleavage and cytotoxic activity. The results indicate that the complexes bind to fish sperm DNA (FS‐DNA) in an intercalative mode via fluorescence spectra, and the five complexes show different cleavage of supercoiled DNA, and then a cytotoxicity assay of these dinuclear palladium(II) complexes on human tumor cell lines was performed. In most of the cell lines, complex 5 ( n =6) and 4 ( n =5) showed much higher cytotoxicity than cis ‐platin. On the other hand, complex 3 ( n =4) was found to be moderately active, and complex 1 ( n =2), complex 2 ( n =3) were found only marginally cytotoxic. Implications of these findings were discussed from a structure‐activity relationship.