Immobilization of metal complexes (Pd, Mn) over mesoporous materials: Synthesis Characterization and application for oxidation, Hydrogenation and C-C coupling reactions

The surface modification of M41S type mesoporous materials by transition metal complexes or reactive organic functional groups allows the preparation of multifunctional heterogeneous catalysts with desired catalytic properties. Taking into account of environmental consideration the hetrogenization of organo-catalyst of transition metal complex over organic-inorganic hybrid mesoporous support such as PMO and SBA-15 are focused. The mesoporosity and very high surface area of the surface-functionalized mesoporous materials can also be exploited for the immobilization of different catalytically reactive species. The principal aim of my research is to investigate the approach of heterogenization of various transition metals complex over solid mesoporous supports (SBA-15) and organic-inorganic hybrid mesoporous materials (PMO) for oxidation, hydrogenation and C-C coupling reactions, under different reaction conditions.
 
          Mesoporous silica materials represent a unique class of silica and organic-inorganic hybrid based materials viz; SBA-15 and PMO act as a support which have received much attention because of their uniform hexagonally ordered two dimensional mesoporous channels structure, high specific surface area, large pore volume, uniform pore size (between 2-50 nm), high hydrothermal stability and rich surface chemistry allowing ready diffusion of reactants to the active sites located in the nanopores. Homogeneous catalyst can be immobilized by different ways such as electrostatic interaction, covalent bonding and simply physical adsorption over support etc. Among the various types of immobilization covalent interaction is superior, which involve direct bonding between organic moieties with heterogeneous support through linker group. The recent discovery of the Cu(I)-catalyzed 1, 3-dipolar cycloaddition of organic azides to alkynes has provided the most powerful “click chemistry” tool for conjugation between appropriately functionalized binding partners via an 1, 2, 3-triazole linkage. Additionally, the surface modification of the synthesized mesoporous materials were done by using various organic and organo silane groups, such as 3-aminopropyltrimethoxysilane (3-APTMS), 3-mercaptopropyltrimethoxysilane (3-MPTMS), 3-azidopropyltrimethooxysilan (3-Az-PTMS) (click reaction) for transition metal complexes anchoring by post synthetic route to develop new class of mesoporous catalysts. In-depth characterizations of all synthesized catalyst systems are highlighted to understand the mode of interaction of the active sites in transition metal complex with the mesoporous silicate network and to evaluate the structure-catalytic activity relations and stability of the mesoporous solids for oxidation, hydrogenation and C-C coupling reactions.