Two new binuclear copper(II) complexes bridged by N-(5-chloro-2-hydroxyphenyl)-N'-[3-(dimethylamino) propyl] oxamide (H3L), and end-capped with 4,4'-dimethyl-2,2'-bipyridine (Me(2)bpy) or 2,2'-diamino-4,4'-bithiazole (dabt), respectively, namely [Cu2L(H2O)(Me(2)bpy)][Cu2L(CH3OH)(Me(2)bpy)] (ClO4)(2)(CH3OH)(0.7) (1) and [Cu2L(CH3OH)(0.25)(dabt)]ClO4 center dot(H2O)(1.5) (2), have been synthesized and characterized by single-crystal X-ray diffraction. In complex 1, the dissymmetric unit of it contains two bicopper(II) cations, the cis-L-3 ligands bridge two copper(II) ions with the corresponding separations of 5.1881(11) angstrom (Cu1 center dot center dot center dot Cu2) and 5.2193(11) angstrom (Cu3 center dot center dot center dot Cu4), respectively. In complex 2, the L-3 ligand is adopting a cis conformation with the Cu center dot center dot center dot Cu distance of 5.2409 (7) angstrom. Through pi-pi stacking and hydrogen bonding interactions, the two bicopper(II) complexes are assembled to 3D supramolecular structures. Cytotoxic activities, and the reactivities towards DNA and protein of the two bicopper(II) complexes are investigated. The results suggest that the two bicopper(II) complexes interact with HS-DNA in the mode of intercalation, and the DNA-binding abilities are consistent with cytotoxic activities following the order of 2 > 1. The protein binding ability has been monitored using bovine serum albumin (BSA) as model protein. (C) 2012 Elsevier B. V. All rights reserved.