Dicyanamide Anion Protracted Assemblies of Cd(II)-Salen Type Coordination Polymers: Synthetic Perspective, Characterization, Crystallographic Notability, DFT Overview, and Biological Appraisal

Abstract

This research delves into a new water-insoluble 1-D coordination polymer (CP), [(dca)Cd(L^2,2)Cd(dca)]_n(1], with a Cd(II) based on a ligand (H₂L^2,2) and sodium dicyanamide (dca), Na⁺(N(CN)₂⁻, which was characterized by spectroscopy, XRD (SCXRD/PXRD), SEM–EDX, ICP-MS, and XPS, to ascertain the structural composition. SCXRD showed that the complex crystallized in the trigonal space group R3c. The Addison parameter (τ) ensures that one Cd(II) has a square-pyramidal geometry and that the other seven coordinated resides in the external O₄ pocket. The compound crystal packing explored weak C–H···π interactions. The Hirshfeld surface (HS) and 2D fingerprint data indicate the presence of significant supramolecular contacts H…N (23.6%) despite the presence of minor O…H (4.3%). Frontier molecular orbital (FMO)/Molecular electrostatic potential (MEP) explains the complex reactivity perspective. The bonding rapports were analysed using the quantum theory of atoms in molecules-noncovalent interactions (QTAIM-NCI), Electron localization function (ELF), and localized orbital locator (LOL) plots. The antimicrobial efficacy of the compounds was assessed against Gram + ve/− ve strains of Escherichia coli, Bacillus subtilis, and Candida albicans. The complex exhibited the most potent antibacterial effects over H₂L^2,2. The structure–activity relationship (SAR) correlates with the biological profile through the chelation/polarization theory of the complex spectrum. Cytotoxicity was evaluated using the Trypan blue exclusion method for Dalton’s lymphoma ascites (DLA) cells and the MTT assay for HepG2 cells. The assay also determined the viability of the human H9c2 cells. Most of the compounds exhibited minimal toxicity toward the H9c2 cell line. The experimental biological findings further confirmed the docking of Staphylococcus aureus and EGFR tyrosine kinase. Overall, these cytotoxic effects imply that higher concentrations of the test compound resulted in decreased cell viability, indicating cell death and a decrease in membrane integrity.