Synthesis and characterization of some new Schiff bases and benzimidazoles and their Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes

Complex heterocyclic compounds containing nitrogen are biochemical entities that play a significant role in the targeted synthesis of physiologically active substances. For inorganic chemistry researchers, examining various biologically important reactions using model systems presents a great opportunity. Schiff bases, benzimidazole derivatives, and similar compounds play important roles in both chemistry and medicine. Particularly, benzimidazole derivatives are privileged structures in medicinal chemistry and are frequently utilized in drug discovery and development due to their wide range of biological activities. The broad pharmacological properties of such compounds render them potential drug candidates and enable them to play a significant role in the treatment of various diseases. For instance, benzimidazole derivatives can exhibit antimicrobial, antiviral, antitumoral, and anti-inflammatory activities. Additionally, Schiff bases and benzimidazole derivatives have the potential to be used in the treatment of various health issues, such as neurodegenerative diseases. Benzimidazole derivatives and Schiff bases are potential ligands for studying complex formation properties. The presence of various hetero atoms and functional groups in these compounds enables them to form various complexes with transition metals. Moreover, the different tautomeric forms of these compounds can also influence complex formation, leading to complexes with different coordination structures with various metal ions. These properties play an important role in the synthesis, structural analysis, and exploration of potential applications of metal complexes. In this doctoral thesis, the aim was to synthesize new Schiff bases and benzimidazolylphenol compounds containing tertiary butyl, chloro, methoxy, and other substituents using known synthesis methods. These compounds were then reacted with Co(II), Ni(II), Cu(II), Zn(II), and Pd(II) salts to obtain complexes, and the structures and various properties of the resulting complex compounds were investigated. In this context, a total of five new Schiff bases and benzimidazolylphenol compounds, along with their corresponding metal complexes, were synthesized, resulting in a total of 40 complex compounds. The obtained ligands and compounds were subjected to various analyses including melting point determination, elemental analysis, FTIR, NMR, UV-visible spectroscopy, mass spectrometry, molar conductivity measurements, and magnetic moment analysis. It was observed that Schiff base ligands H2SB1, H2SB2, H2SB3, H2SB4, HSB5, and benzimidazole derivative ligands HBz1, HBz2, HBz3 reacted with metal salts in 1:1 and 2:1 ratios, and their molecular weights were confirmed through elemental analysis. Peaks corresponding to Schiff bases and benzimidazole derivatives were observed in the infrared and NMR spectra and tabulated. Single crystals of the ligands H2SB1, H2SB2, H2SB4 and HSB5 were obtained and their crystal structures were examined. Additionally, magnetic moment measurement results provided important contributions to understanding the geometries and structural properties of the complex compounds. UV-visible spectroscopy data indicated intramolecular charge transfer transitions in the ligands, while in the complexes, transitions from the ligands to the metals were observed. Furthermore, the antibacterial, antifungal, and antiviral activities of the obtained ligands and complexes were tested to investigate how substituents and metal ions affected these properties.