New phthalazine based nickel (II), cobalt (II), and copper (II) mixed-ligand complexes; characterization, physicochemical properties, anti-inflammatory, antifungal, antibacterial, DFT and molecular docking exploration

Abstract

In this study, we have employed a straightforward and easily synthesized ligand, namely 1,4-dioxo-3,4-dihydrophthalazine-2(1H)-carbothioamide (DDPC), in conjunction with 8-hydroxyquinoline (QOL) to create new mixed-ligand complex compounds such as Co (II) (C1), Ni (II) (C2), and Cu (II) (C3). Recent research has been dedicated to investigating their antibacterial, antifungal, & anti-inflammatory efficacy. Our approach involved the synthesis and characterization of these novel C1, C2, and C3 mixed-ligand complexes using various analytical methods, having elemental analysis, MS, FT-IR, UV spectroscopy, magnetic, TGA, and stoichiometry analysis by molar ratio methods. Octahedral structures were identified for isolated metal complexes. Utilizing density functional theory (DFT), we estimated the quantum chemical characteristics and optimized molecular structures for each compound. To evaluate their effectiveness in inhibiting the proliferation of harmful microorganisms, a disc diffusion test was conducted. The produced complex compounds displayed meaningfully improved antibacterial & antifungal effectiveness in comparison with the free ligands. Additionally, we investigated the anti-inflammatory effects employing the Egg albumin denaturation method. C1, C2, and C3 complexes demonstrated substantial anti-inflammatory potential, surpassing the free ligands & showing analogous efficacy to standard references. Molecular docking analyses against 5JQ9 and 6CLV from Escherichia coli, Staphylococcus aureus, and COX-2 (5IKT) as an anti-inflammatory effectiveness of enzymes confirmed the bioactivity. Among the tested compounds, C3 exhibited the highest binding affinity, suggesting its potential as a building block for the development of new antibiotics. Finally, we correlated the DFT and molecular docking results with in vitro activities and provided a comprehensive discussion.