Synthesis and Characterization of New Schiff Bases Ligands with their Transition and Actinide Metals
Date of Award
Doctor of Philosophy
Dr. Ekkehard Sinn
Dr. Ramakrishna Guda
Dr. Michael J. Barcelona
Dr. William W. Cobern
Over recent years a great deal of interest has developed in new transition metal complexes of Schiff base ligand. The preparation of new ligand is the most important step in the development of metal complexes that exhibit unique properties and novel reactivity. The electron donor and electron acceptor properties of the ligand, the structural function groups and the position of the ligand in the coordination sphere, together with the reactivity of coordination compounds may be the factor for different studies. The synthesis and structural investigations of Schiff bases and their metal complexes are a considerable center of attention because of their potentially beneficial pharmacological properties and a wide variation in their mode of bonding. Metal coordination complexes have a wide variety of technological and industrial application, ranging from catalysis to anticancer drugs. In these compounds the metal atom itself may have a number of roles, based on its coordination geometry, oxidation state, and magnetic electronic and photochemical behaviors.
This study presents the synthesis, characterization, and structural studies of different series of Copper and Uranium complexes of salicylaldehyde Schiff base derivatives with various organic amine compounds. The Schiff bases act as neutral and bidentate ligands, which can attach the metal through the azomethine nitrogen and furfural oxygens. These Schiff bases are prepared by iii reacting salicylaldehyde with various organic amines. In the case of most complexation reactions, highly colored precipitates were formed immediately. The complexes were found to have composition ML2 and M2L2, where M is the metal and L the organic ligand. This implies “mononuclear” structures with one metal + 2 ligands, and “binuclear” where the ligands hold two metal atoms in close proximity.
The interesting molecular and crystal structural features of the Schiff base ligand called E-2-((benzo[d]thiazol-2-ylimino)methyl)phenol and its Cu(II) complex are presented in Chapter 2. Further investigations on the coordination chemistry of the Schiff base ligands are made by reacting these ligands with copper and uranium, described in Chapter 3.
Another series of dicopper(II) complexes and diuranium complex of the Schiff base ligands, containing azomethine nitrogen and furfural oxygen donor group are investigated to evaluate the role of alkoxo bridge on the structures. Making the compounds with two uranium atoms leads to very high molecular weight, as a path to the highest molecular weight liquid crystal. This lays the pathway to future work for making those crystals. These dinuclear complexes are presented in chapter 4.
The objective of the present study is to investigate the coordination chemistry of these ligands with Copper and Uranium. For the ligands this was done by a combination of nuclear magnetic resonance spectroscopy, infrared spectroscopy, ultraviolet-visible spectroscopy and single X-ray crystallography. The metal complexes were analyzed by the same techniques, except that in the case of uranium, all efforts to obtain single crystal for X-ray crystallography proved unsuccessful, so the molecular structure had to be ascertained from the other techniques.
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Jabrou, Sali Nabeel Hanna, "Synthesis and Characterization of New Schiff Bases Ligands with their Transition and Actinide Metals" (2019). Dissertations. 3466.