Crystallographic and computational investigation of a bent-core Schiff base Ni(ii) complex with DNA and protein...

The rational design and synthesis of a three-ring bent-core Schiff base ligand, (E)-4-(trifluoromethyl)phenyl-3-((4-butoxy-2-hydroxybenzylidene)amino)-2-methylbenzoate (HL), and its mononuclear Ni(ii) complex, [Ni(L)₂] (1), are described. The presence of a polar -CF₃ group and a flexible butoxy chain imparts amphiphilic character to HL and induces aggregation-induced emission (AIE) behavior. Coordination with NiCl₂ yields a square-planar complex, as confirmed by spectroscopic methods, single-crystal X-ray diffraction analysis, and topological analysis. Fluorescence and SEM studies substantiate the aggregation propensity of HL. Density functional theory (DFT) and natural bond orbital (NBO) analyses reveal pronounced ligand-to-metal charge transfer in (1) and a moderate HOMO-LUMO gap of 4.00 eV, indicative of kinetic stability and optoelectronic relevance. Complex (1) exhibits strong binding affinity toward duplex DNA and serum proteins (BSA and HSA), evidenced by red-shifted fluorescence enhancement at 475 nm and low detection limits (0.075-0.188 µM). Molecular docking further supports stable BSA binding (-8.52 kcal mol^-1), highlighting the potential of this Ni(ii) system for biomolecular recognition.