Unlocking Biomedical Potential of the [Cu( l -isoleucine)(1,10-phenanthroline)(H ₂ O)]Cl·2H ₂ O Complex: A Comprehensive Study of Synthesis, Spectroscopic Analyses, Antitumor Efficacy, and Computational Insights

We report the synthesis and comprehensive characterization of a ternary copper(II) complex, [Cu(l-isoleucine)(1,10-phenanthroline)(H2O)]Cl·2H2O, combining single-crystal X-ray diffraction (SCXRD), ultraviolet–visible (UV–vis), Fourier-transform infrared (FT-IR), and Raman spectroscopy, and Hirshfeld surface analyses, with molecular docking, and in vitro cytotoxicity assays. SCXRD reveals a distorted square-pyramidal Cu(II) center (monoclinic, P21 (C22) space group, 300 K). Hirshfeld analysis indicates that H···H (52.8%), O···H/H···O (17.4%), and Cl···H/H···Cl (10.3%) contacts dominate the crystal packing. Docking of the biologically main cation [Cu(l-Ile)(phen)(H2O)]+ predicts favorable binding to deoxyribonucleic acid (ΔG = −8.26 kcal/mol) and bovine serum albumin (ΔG = −7.17 kcal/mol), supported by π–π and electrostatic interactions. The complex exhibits a dose-dependent antiproliferative effect against SiHa cervical carcinoma cells (IC50 = 2.57 μM) and comparable toxicity toward GM07492A fibroblasts (IC50 = 2.77 μM), yielding a selectivity index of 1.08. These findings establish a structurally validated Cu(II) mixed-ligand complex and provide an integrated experimental-computational framework for future optimization toward improved biological selectivity.