ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis and characterization of a sulpha drug-derived Cu(II) complex: crystal structure of the Schiff base and biological insights

Valarmathy Govindaraj, Pradeepalakshmi Mathiazhagan, Subramanian Ramasamy, Elias Jesu Packiam, Subbalakshmi Ramanathan, Durga Dhanabal, and Keerthanadevi Chandrasekran

PG and Research Department of Chemistry, Seethalakshmi Ramaswami College, (Affiliated to Bharathidasan University, Tiruchirappalli), Tiruchirappalli, India

E-mail: valarchola@gmail.com

Received: 12 June 2025  Accepted: 23 March 2026

Abstract:

A bioactive copper(II) complex [Cu(L-H)₂], was synthesized using a Schiff base ligand derived from sulfamethoxazole and 2-hydroxybenzaldehyde. The ligands coordinate to the Cu(II) center, resulting in a distorted octahedral geometry around the metal ion. The complex was characterized using FT-IR, UV–Vis, NMR, mass spectrometry, EPR, and thermal (TGA/DTA) analysis. EPR spectral parameters (g∥ > g⊥ > 2.0023) indicated an axially elongated octahedral environment and a covalent metal–ligand interaction. Single-crystal X-ray diffraction (SC-XRD) of the free Schiff base ligand confirmed a triclinic crystal system (P-1), stabilized by classical and non-classical hydrogen bonding interactions. DFT and MESP analyses revealed a HOMO–LUMO energy gap of 0.80 eV and reactive electrostatic sites. Molecular docking studies against β-catenin (PDB: 1JPW) demonstrated strong binding affinity (–9.40 kcal/mol), surpassing that of doxorubicin. The complex also exhibited enhanced fluorescence, significant antioxidant activity (IC₅₀ = 66.11 µg/mL), and potent antimicrobial efficacy. These multifaceted findings emphasize the bioactive potential of the Cu(II) complex in medicinal and pharmaceutical research.

Graphical abstract

Keywords: Schiff base; Bioactive Cu(II)complex; SC-XRD; Hydrogen bonding; DFT; Antioxidant; Docking; Antimicrobial

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04868-5

Chemical Papers 80 (7) 7973–7987 (2026)