Structure–function relationships in a square-planar Cu(ii) hybrid halometalate: experimental, DFT, molecular docking, optical, and biological studies

Abstract

A novel organic–inorganic copper(ii) hybrid halometalate, (C6H8BrN2)2[CuBr4], was successfully synthesized and investigated using complementary experimental and computational approaches. Single-crystal X-ray diffraction analysis revealed discrete square-planar [CuBr4]2− anions embedded within a three-dimensional supramolecular architecture stabilized by N–H⋯Br hydrogen bonds, π–π stacking interactions, and halogen contacts. Optical studies indicated semiconducting characteristics with an estimated band gap of approximately 2.5 eV, together with a broad visible emission assigned to ligand-to-metal and/or charge-transfer transitions. Density functional theory (DFT) calculations yielded a HOMO–LUMO energy gap of 2.78 eV, consistent with the observed electronic properties, while ADMET predictions suggested acceptable aqueous solubility, moderate membrane permeability, limited blood–brain barrier penetration, and no P-glycoprotein substrate liability. Molecular docking showed favorable binding affinities toward human α/β-tubulin (PDB ID: 5J2T; −5.12 kcal mol−1) and human peroxiredoxin 5 (PDB ID: 1HD2; −4.85 kcal mol−1), in agreement with the experimentally observed antiproliferative and antioxidant performances. Biological assays further confirmed moderate free-radical scavenging capacity in DPPH and ABTS tests, together with significant cytotoxic effects against HCT-116 and HepG-2 cancer cell lines. Overall, these results establish (C6H8BrN2)2[CuBr4] as a multifunctional Cu(ii)-based hybrid material with promising prospects for both optoelectronic and biomedical applications.