Two Octahedral Ni(II) and Cu(II) Mixed-Ligand Complexes Incorporating 2,6-Di(1H-Pyrazol-1-yl)Pyridine and 4,4′-Bipyridine: Synthesis, Characterization, In Vitro Bioactivity, and Molecular Docking Exploration

This study focuses on the synthesis, characterization, and evaluation of NiBIDP and CuBIDP mixed-ligand complexes. Synthesized with high yields in ethanol-based solutions, these complexes demonstrate exceptional stability and non-hygroscopic properties, with melting points exceeding 300 degrees C. Solubility tests reveal compatibility with organic solvents such as acetonitrile, DMF, and DMSO, while being insoluble in water. Characterization through UV-visible, IR, and mass spectrometry confirms octahedral coordination geometries around Ni(II) and Cu(II) centers. Thermal stability assessments indicate robust properties up to 180 degrees C for NiBIDP and 170 degrees C for CuBIDP. Computational analyses reveal significant electron localization and enhanced electron-accepting capabilities in CuBIDP, as evidenced by its low LUMO value and high electrophilicity index. Molecular electrostatic potential (MEP) analyses identify nucleophilic sites important for protein interactions, underscoring their potential in catalysis and materials science. Biological evaluations show that although the BI and DP ligands exhibit moderate antimicrobial, anti-inflammatory, and antioxidant activity, their metal complexes, particularly CuBIDP, demonstrate enhanced efficacy. Molecular docking studies further highlight the improved binding affinities of NiBIDP and CuBIDP with target proteins, suggesting their potential as therapeutic agents in drug discovery. In conclusion, this study provides significant insights into the structural, electronic, and biological properties of NiBIDP and CuBIDP complexes, supporting their development as versatile compounds in biomedical and materials science applications. Key outcomes include enhanced stability and bioactivity of metal complexes compared with their ligands, as well as promising therapeutic potential revealed through molecular docking analyses.