A Novel Nickel(II) Complex Featuring Furan‐Based Dithiocarbazate Schiff Base: Synthesis, Crystal Structure, DFT Insights, Optical Properties, and Molecular Docking Against Cyclooxygenase‐2 Enzyme

Abstract A novel furan‐derived Schiff base ligand, S ‐octyl‐3‐(furan‐2‐ylmethylene)dithiocarbazate (HL), and its nickel(II) complex (NiL 2 ) were synthesized and comprehensively characterized using FTIR, UV–vis, NMR, HRMS, and single‐crystal X‐ray diffraction (SC‐XRD). Crystallographic analysis revealed that HL crystallizes in the triclinic system P in its thione tautomeric form, while NiL 2 crystallizes in monoclinic space group P 2 1 /c with the metal exhibiting a slightly distorted square‐planar geometry featuring trans N,S‐chelation. Hirshfeld surface and fingerprint plot analyses confirmed the presence of dominant H···H and S···H contacts, with enhanced supramolecular organization in the solid state. DFT calculations revealed small HOMO–LUMO energy gaps (3.627 eV for HL; 3.401 eV for NiL 2 ) and exceptional nonlinear optical (NLO) properties for HL, with first hyperpolarizability (β total ) up to 2.53 × 10 −30 esu, over six times higher than urea, and a dipole moment of 5.76 D. Natural bond orbital (NBO), natural population analysis (NPA), and reduced density gradient (RDG) analyses indicated strong charge delocalization, hyperconjugation, and van der Waals interactions. Molecular docking simulations against the cyclooxygenase‐2 (COX‐2) enzyme (PDB ID: 5F19) revealed an effective binding affinity of HL (−6.5 kcal/mol) and NiL 2 (−8.1 kcal/mol), outperforming several standard nonsteroidal anti‐inflammatory drugs (NSAIDs).