Synthesis, Characterization, X- ray Crystal Structure, Electrochemical Properties and DFT Studies of Metal(II) Complexes

A series of divalent transition metal(II) complexes derived from chalcone-based ligands were synthesized and thoroughly investigated. The chalcone derivatives were prepared via Claisen–Schmidt condensation and subsequently coordinated with selected transition metal(II) ions to afford stable complexes. The synthesized compounds were characterized by elemental analysis, molar conductivity, FT-IR, UV–Vis, (for diamagnetic complexes), and mass spectrometry, confirming the proposed ligand coordination modes. Single-crystal X-ray diffraction analysis of a representative complex revealed the exact molecular structure and coordination environment around the metal(II) center, exhibiting a well-defined geometry stabilized by intra- and intermolecular interactions. The electrochemical behavior of the complexes was examined by cyclic voltammetry, displaying metal-centered redox couples with reversible or quasi-reversible characteristics. Density Functional Theory (DFT) calculations were performed to optimize the molecular geometries and to elucidate the electronic structures of the complexes. The calculated frontier molecular orbitals, energy gaps, and theoretical spectral parameters showed good agreement with the experimental findings. The combined experimental and computational results provide valuable insights into the structural, electronic, and redox properties of chalcone-based metal(II) complexes, underscoring their potential applications in coordination chemistry and functional materials.