Synthesis, crystal structure and DNA/protein binding of tetranuclear Cu(II) complexes with a double-open-cubane like core framework

摘要

The copper(II) complexes [Cu-4(L)(2)(HL)(2)(H2O)(2)]center dot 2(ClO4)center dot 2(H2O)center dot DMF (1) and [Cu-4(L)(2)(HL)(2)(H2O)(2)]center dot(tP) (2) [H2L = 2-ethoxy-6-[(1-hydroxymethyl-propylimino)-methyl]-phenol; tp = terephthalate] have been synthesized and characterized by single crystal X-ray diffraction and spectroscopic studies. The structural determination reveals that both the complexes are tetranuclear with a double-open-cubane like core framework. The 2D supramolecular structure of 1 and 3D supramolecular structure of 2 are formed through C-H center dot center dot center dot pi and hydrogen bonding interactions, respectively. At room temperature both the complexes exhibit fluorescence with quantum yields of 0.41 and 0.40. The interactions of the complexes with calf thymus DNA (CT-DNA) and serum albumins were investigated using electronic absorption and fluorescence spectroscopic techniques. The studies revels that the binding affinities of 1 and 2 with CT-DNA are of the order 8.86 x 10(5) M-1 and 7.14 x 10(5) M-1, respectively. Additionally, the interaction of the complexes with bovine serum albumin and human serum albumin were studied and the number of binding sites and binding constants were calculated using a double logarithm regression equation. The redox activities of the complexes were investigated in methanol solution by cyclic voltammetry. (C) 2018 Elsevier Ltd. All rights reserved.