Preparation Of Graphene Supported Metal Complex Systems &their Applications In Catalysis

As a new star of the carbon nanomaterial family, graphene has aroused great interests in related theoretical research and applications owing to its unique two-dimensional structure and extraordinary properties. In the heterocatalysis field, graphene can not only act as high-performance heterogeneous catalysts via functional modifications, but also displays great advantages in supporting catalytic active species. These properties endow graphene great potential as a desirable support for immobilizing metal complex catalysts. Considering the limitations and shortcoming of previous studies, this research aims at raising new general methods of immobilizing metal complexes with graphene-based materials and preparing efficient and recyclable heterogenized coordination catalysts, which builds the bridge of graphene-based materials and heterogeneous coordination catalysis.This research begins with the establishment of a new method by covalent immobilizing of the Wilkinson’s catalyst [RhCl(PPh3)3] on graphene-based support. Graphene oxide(GO) was amine-functionalized through a silylation process, and the Wilkinson’s catalyst was subsequently immobilized on the graphene-based support by axial coordination interaction, with a metal loading density of 0.42 mmol g–1. Hydrogenation of cyclohexene was selected as probe reaction, and the heterogenized catalyst was highly effective and showed several times enhancement in the catalytic activity compared with its homogeneous analogue. An excellent recyclability and reusability has also been achieved, and the conversion remained unchanged after 5 run reuse.This study further investigated the influence of immobilization ligands on the catalytic property. Based on the covalent immobilization methodology, a ruthenium complex [RuCl2(PPh3)3] was immobilized on the graphene-based support. The immobilization ligands endowed the heterogenized catalyst double catalytic effects, which exhibited high catalytic efficiency towards the hydrogenation of olefins and ketones, with a higher conversion and chemoselectivity for olefins. The immobilized catalyst could also be recovered and reused for at least 5 cycles without observable deterioration.This study combines the preparation and immobilization of metal complexes together. Serving as a flat formwork, GO provided a platform for the growth of copper(salen) complex via a “Graft from” method, and thus a copper(salen) complex was in situ synthesized and immobilized on graphene-based support. The immobilized copper(salen) complex served as an active catalyst for the epoxidation of olefins. In addition, the double-grafting immobilization method ensured the high stability of the catalyst, which could be reused for successive 12 times without discernible activity deterioration. This method provides research foundation for the application of graphene-based coordination catalysts in industry manufacture.A tertiary organic amine and diamine ligand were immobilized on graphene oxide by a one-pot bifunctionalization process, and a palladium(diamine) complex was subsequently in situ synthesized. Thus, a synergistic catalysis system based on the graphene support was built. The immobilized tertiary amine showed excellent synergistic catalysis effect with the palladium(diamine) complex, and a yield of 91.85% was obtained for the Tsuji–Trost allylation. The synergistic catalyst could also be readily recovered and reused for at least 5 times without reduction of its efficiency. This research provides experimental support for the establishment of multifunctional coordination catalysis system based on the graphene platform.