Synthesis, crystal structures, and biological properties of a new naphthalimide Schiff base and its copper(II) complex

A new naphthalimide Schiff base N-allylamine-4-(ethylenediamine-3-methoxysalicylidene)-1,8-naphthalimide (HL) and its copper(II) complex {N-allylamine-4-(ethylenediamine-3-methoxysalicylidene)1,8- naphthalimide copper(II)} (CuL2) have been synthesized and characterized. The crystal structure of CuL2 has been determined by X-ray single crystal diffraction. The central Cu(II) ion is four-coordinate with an N2O2 donor set which is afforded by two L ligands, forming a slightly distorted square planar geometry. The interactions of HL and CuL2 with calf thymus DNA were investigated using electronic absorption titration, fluorescence titration, and viscosity measurements. The results indicate that free HL and CuL2 bind to DNA in an intercalation mode, and their binding affinity for DNA takes the order CuL2 > HL. Moreover, the antioxidant assay in vitro also shows that HL and CuL2 possess significant antioxidant activities and CuL2 is more effective than free HL. [GRAPHICS] .