New Cu(i) square grid-type and Ni(ii) triangle-type complexes: synthesis and characterization of effective binders of DNA and serum albumins

Abstract

Multivalent molecules are a potential group of bioactive compounds endowed with high affinity and specificity in innovative biomolecule-targeting therapeutic approaches. Herein, we report on a new and versatile N,N,N,N-donor ligand L (1R,4R)-N1,N4-bis(quinolin-2-ylmethylene)cyclohexane-1,4-diamine with two coordinating quinoline moieties connected with trans-1,4-diaminocyclohexane. It coordinates Cu⁺ forming a [2 × 2] square grid-type complex C1 [Cu₄L₄]⁴⁺ and Ni²⁺ giving a triangle-type complex C2 [Ni₃L₃]⁶⁺. We screened their potential as versatile metal-based Serum Albumin (SA), double helical and G-quadruplex DNA binders taking advantage of their shape, size and stability effects using different spectroscopic experiments (UV-Vis, fluorescence, circular dichroism). The findings of our work suggest the potential utility of the metal complexes herein described in the context of the new drug discovery.