The Assembly And Properties Of Metal Complexes Containing Tripodal Triarylamine Ligands

The ability of coordination complexes to catalyze chemical transformation collaboratively with enzyme is of importance in the field of synthetic enzyme mimics. Of these promising examples reported using transition metal complexes as redox catalysts, the highly active systems incorporating environmentally friendly organic dye as sensitizers are high desirable. By incorporating thiosemicarbazone as metal binding chelators and potential guest accessible sites, a new approach to create metal-organic redox vehicles was achieved for photocatalytic hydrogen evolution from water. MOFs are ideally suited for homogeneous asymmetric catalysts, because they can impose size-and formselective restriction through readily fine-tuned channels and pores, we realized the homochiral crystallization of silver-based catalysis MOFs by using cinchonine or cinchonidine as chiral templates.By incorporating a phosphine donor within a thiosemicarbazone moiety, new proton reduction catalysts Co-thioP and Ni-thioP were synthesized and structurally characterized. In particuarly, the oxidative quenching process of Ni-thioP toward fluorescein enable was able to prolong the lifetime of whole system. The direct generation of H2was achieved by carrying out the photolysis of a solution containing fluorescein as the photosensitizer, triethylamine as the sacrificial and the redox catalysts. Ni-thioP exhibited excellent activity with a turnover number (TON) of8000moles of H2per mole of the catalyst after24hours and an initial TOF larger than500moles of H2per catalyst per hour. The presence of Ni… interactions relative to the amide group coupled with the easy proton immigration pathway involving thioamide/thiolate tautomer exchange indicated that the thiosemicarbazone complexes could serve as promising candidates for proton reduction.By combining three thiosemicarbazone bidentate chelators in the ligand backbone, herein, this work developed a new approach to assemble metal-organic redox vehicles. By pushed the essential components closer together to avoid unwanted energy transfer and reverse ET process, the modified supramolecular AP system exhibited excellent activity in light driven hydrogen evolution with the TON and initial TOF reaching to11000per mole catalyst and750per mole catalyst per hour, respectively. Competitive inhibition behavior was found upon addition of ATP to the reaction mixture and suggested that the photolysis occurred in the pocket of Co-TFT. Controlled experiments based on the mononuclear compound and a smaller tetrahedral analogy confirmed that the superiority of supramolecular systems over others was attributed to the closed proximity between the redox sites and photosensitizer, and the more powerful PET pathway driven by the potential oxidative quenching. By incorporating three pyridine-imine bidentate chelators into a triphenylamine fragment, this work realized the homochiral crystallization of silver-based MOFs by using cinchonine or cinchonidine as chiral templates. This work represents a new strategy for the creation of homochiral metal-organic frameworks for intrinsically asymmetric metal catalysis. The distorted tetrahedrally coordinated silver centers act as lattice nods to connect the ligand in a chiral (10,3)-a net, and locate within the chiral pores to interact with the active site of the substrate, thus ensuring the successful application in the asymmetric [3+2] cycloaddition. The structural simplicity of the building blocks and the ability to control the assembly process through conformational chiral adducts make this system a promising one for the development of a wide range of homochiral materials.