DNA/protein binding and molecular docking studies of two tetranuclear Cu(II) complexes with double-open-cubane core like structure

Abstract

Two Cu(II) complexes [Cu4(L)2(HL)2(H2O)2](pv)2 (1) and [Cu4(L)2(HL)2(H2O)2](ssal) (2) [H2L = 2-ethoxy-6-[(1-hydroxymethyl-propylimino)-methyl]-phenol; pv = pivalate; ssal = 2-Hydroxy-5-sulfosalicylate] have been synthesized and characterized by X-ray structure determination. Structure determination reveals that both the complexes are tetranuclear with double open cubane core framework, and C-H⋯π interactions results the formation of 1D supramolecular structure. At room temperature 1 and 2 show fluorescence (λex = 267 nm, λem = 329, 516 and 620 nm for 1; λex = 277 nm, λem = 315 and 413 nm for 2) with fluorescence quantum yield 0.41 and 0.46, respectively. Interactions of complexes with calf thymus DNA (CT-DNA), bovine serum albumin (BSA) and human serum albumin (HSA) were studied using UV–vis absorption and fluorescence spectroscopic techniques, and the calculated values of intrinsic binding constants of 1 and 2 with CT-DNA are 2.71(±0.07) × 104 M−1 and 1.58(±0.11) × 104 M−1, respectively. Molecular docking technique has been used to determine the mode of interaction of complexes with CT-DNA and serum albumins. The docking studies suggest that both the complexes can interact with DNA through groove binding mode, and possible binding sites of complexes with BSA and HSA are in the proximity of Tyr149 and Tyr150, respectively.