Recent advances in 3d-block metal complexes with bi, tri, and tetradentate Schiff base ligands derived from salicylaldehyde and its derivatives: Synthesis, characterization and applications

Schiff bases have been of continued interest in coordination chemistry for a long time because they provide new ligand platforms that make reactivity easier and their metal complexes represent one of the most adaptable and well-established fields of research. Because of their numerous uses in analytical, pharmaceutical, organic, bioinorganic and metal catalysis, as well as material science, there is a notable interest in Schiff bases and their metal complexes. For these applications, the Schiff bases must have an azomethine group that can link with various metal ions. Recognizing the accessibility and simplicity of multidentate Schiff bases and related metal complexes, it is essential to investigate these compounds so that we can understand structure-property connections in an effort to maximize and enhance their applications in a variety of domains, such as catalysis, energy materials, supramolecular chemistry, electrochemistry, magnetism, nanoscience, and biological applications. This review underlines the current progress of bi, tri and tetradentate Schiff bases originating from salicylaldehyde and their derivatives having different donor sets of N and O- atoms and their complexes with 3d-block transition metal ions in addition to describing synthetic procedures and fascinating structures of complexes designed by the transition metals. The present review article is split into three core units, each consistent with Schiff bases having one type of denticity and their metal complexes including an outline of their synthesis, characterization and applications. The present paper containing 262 references would provide important knowledge for investigators which are concerned with this field and inspire them for further research in this attractive field of Schiff base complexes.