Anion binding and catalytic studies of metal salen complexes .

摘要

Of all the substrates and cofactors involved in biological processes, it is estimated that 70-75% of the species are negatively charged. Since anionic species are essential for life, their presence or imperfect regulation can be either beneficial or harmful to living organisms. Despite the importance of anions in nature, the recognition of anions by synthetic hosts has been largely unexplored. A series of tripodal triphenoxymethane salens were synthesized and then used to chelate lanthanides and transition metals with 3+ oxidation states. The metal chelation facilitates the formation of well-defined binding pockets containing six O-H moieties of varying sizes depending upon the chelated metal ion. The same approach was also used to produce large macrocyclic urea-based salen ligands and the corresponding metal complexes as well as mixed O-H/N-H metal salens. Both the O-H and N-H based complexes were treated with the tetrabutylammonium salts of a wide range of anion and then studied for their anion binding capabilities.;Chiral metal salen molecules have also been used extensively to perform asymmetric catalysis. A series of chiral BINAM triphenoxymethane-based salen ligands were produced and used to synthesize extremely bulky chiral dinuclear catalysts. These catalysts were found to facilitate the asymmetric addition of ZnEt2 to benzaldehyde giving a secondary alcohol. In addition, the chiral BINAM catalysts can also produce quantitative amounts of cyclic carbonates through a cycloaddition reaction of CO2 to epoxides. The synthesis of the metal salen complexes and the results of the anion binding and catalytic studies are presented herein. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)