Construction Of NAD~+ Model-based MOFs For Catalytic Aerobic Oxidation Of Alcohols

Catalysis is at the heart of chemistry and provides tools for efficiently and selectively making and breaking chemical bonds that are crucial for converting basic chemicals into useful products for society in a sustainable fashion, especially in redox. Nicotinamide adenine dinucleotide (NAD+) as an important coenzyme of organisms has the ability to carry protons and electrons and transmit energy which are the essential process of redox reactions in organisms. For now the research is mostly based on the NAD+ models which are easily synthesis and have a breadth of reaction conditions, but not the NAD+ coenzyme which is most stringent to temperature and acidity and alkalinity of reaction system, and it also has the weakness of difficult to separate from organisms and cost much as the catalysis. For this reason, which is extremely important ability to reuse catalysts in a heterogeneous manner, reduces potentially the processing and waste disposal costs in large-scale reactions.Metal-organic frameworks are hybrid crystal solids with the infinite network structures built from organic bridging ligands and inorganic connecting nodes. Besides the potential applications in many diverse areas, MOFs are ideally suited for catalytic conversions, since they can endow size and shape selective restriction through readily fine-tuned channels or pores, providing precise knowledge about the pore structure, the nature and distribution of catalytically active sites. In comparison to the heterogeneous catalytic systems that have been examined earlier, the design flexibility and framework tenability resulting from the huge variations of metal nodes and organic linkers allow the introduction of more than two independent catalysts in one single MOF. Accordingly, the incorporation of an organic functional group within MOF-based metal catalyst possibly is a promising approach to create new synergistic catalysts combining enzyme model and metal catalytic cycles.Some new interesting 2D MOFs were synthesized successfully with the ligand of tricarboxylic and easy negatively charged NAD+ models and among which the zinc-based MOFs exhibited a high efficiency for the photo-oxidation of benzyl alcohols with the turnover number (TON) reached to 150 while irradiation by Hg light at room temperature under air atmosphere. Moreover, the composite enabled to solve the dilemma of aggregation and recycle of NAD+ model in homogeneous catalysis process.A charge neutrality dicarboxylic NAD+ model ligand was designed and synthesized to break the charge restriction of ligand. A 3D porous MOFs was constructed by the ligand and zinc ion, which were used in the reaction of photocatalytic oxidation of alcohols, through a self-assembled process under solvothermal conditions. Under air atmosphere, the MOFs exhibited a high photocatalytic activity (TON number of 170) for oxidation of benzyl alcohol while irradiation of Hg light at room temperature. At the same time, the NAD+-based MOFs could provide a Lewis acid active site in the catalytic reaction which is benefit for simulating the synergistic catalytic behavior of biological enzymes and coenzymes in the organism. These results demonstrated the significance of the ligand choice to control the structure and the function of the metal ion, highlighting the cooperation of functional components in one MOF.