The Metal-organic Macrocycle Containing NADH Model For Catalytic Research

The enzyme in life which is one kind of proteins has high catalytic efficiency, but the enzyme as active material is vulnerable to inactivation by environmental factors. Since 1978, Professor Lehn J. M. proposed supramolecular chemistry theory, using supramolecular chemistry theory to solve the problems about the synthesis of artificial enzymes has drawn increasing interest in supramolecular chemists. Small and complementary molecules can be made to recognize each other through noncovalent interactions such as hydrogen bonding, charge-charge, donor-acceptor, ?-?, and van der Waals, etc. Such "programmed" molecules can thus be self-assembled by utilizing these interactions in a definite algorithm to form large supramolecules that have different physicochemical properties than those of the precursor building blocks. Typical systems are designed so that the self-assembly process is kinetically reversible; the individual building blocks gradually funnel toward an ensemble that represents the thermodynamic minimum of the system via numerous association and dissociation steps. By tuning various reaction parameters, the reaction equilibrium can be shifted toward the desired product. As such, self-assembly has a distinct advantage over traditional, stepwise synthetic approaches when accessing large molecules. Currently, supramolecular chemistry has a wide range of applications in molecular recognition, catalysis, storage and other fields.Deriving two arms ligands of tridentate NNO coordination sites through Schiff base reaction, coordination with transition metal Ni ion self-assembly, Ni-ZPB metal-organic four-member ring structure is obtained. Ru(bpy)3(PF6)2 works as photosensitizer,ascorbic acid works as electron sacrificial agent, Ni-ZPB works as catalyst to model a hydrogenase in nature catalytic center structure, to achieve light-driven hydrogen product research. Ni-ZPB containing dihydropyridine amide group improves elector transfer rate, so that it makes the whole hydrogen product system shows higher catalytic efficiency.By incorporating NADH active center within the ligand backbone, a NADH model nickel-based square Ni-ZPB was developed as a renewable molecular reactor for the construction of artificially photosynthetic system. Under low pressure of hydrogen gas, a catalytic amount of the catalyst Ni-ZPB work as hydrogen source that could be regenerated in situ by light-driven H2 evolution is able to encapsulate benzoxazinone within its cavity for biomimetic hydrogenation of benzoxazinone with up to 98% yield in the absence of other catalysts. This renewable reactor that could imitate complete natural photosynthesis for the regeneration of square Ni-ZPB makes this hydrogenation a more perfect atom economic process. It's the first time to realize regeneration of hydrogen source without high pressure of hydrogen gas.