Synthesis Of Supramolecular Artificial Enzymes For Precise Confinement Catalysis And Its Applications

The study of supramolecular artificial enzymes belongs to the intersection of supramolecular chemistry with biochemistry and organocatalysis.Based on the excellent catalytic effect of natural enzymes in living organisms for reactions,the construction of artificial enzymes comparable to them is of great significance for organic synthesis and drug screening,and has been a challenge and goal pursued by chemists.The coordination supramolecule has been the object of research in the field of artificial enzyme simulation for decades due to its advantages of high designability and high yield.However,there is a lack of a supramolecular structure with large domain-limited cavity and high controllability,so only the active center of natural enzymes can be simulated,and it is difficult to comprehensively simulate the complex domain-limited environment of natural enzymes.In this paper,we propose a new method to transform two-dimensional supramolecular structures into three-dimensional supramolecular structures by using transition groups to design and synthesize complex organic ligands using tripyridines as ligand elements,and to form a stable,highly symmetrical coordination self-assembly with transition metal ions.The complex organic ligands were designed and self-assembled with transition metal ions to form a stable and highly symmetric three-dimensional coordination supramolecular polyhedra.These supramolecules have ultra-large domain-limited cavities and quantitatively carry multiple internal modification groups.(1)In the second chapter,two ligands 3a and 3b were successfully designed and synthesized to provide modification sites in the formed supramolecular cages,which were assembled with metallic zinc to obtain a cubic truncated octahedral supramolecule consisting of 24 metals and 72 anions.NMR and MS were used as characterization tools to confirm that the resulting supramolecular configuration was the expected simulated cubic truncated octahedron.The central group of the ligand has a hydroxyl group,and the ligand can be used as an intermediate to connect various functional groups,making the functionalization of the supramolecular cage easier.The cubic truncated octahedral supramolecular cage has a large cavity,which can wrap large target substances,and there are functional groups inside the cage,which can identify the wrapping target and specific recognition target more directly,and save a lot of tedious experiments on wrapping,which is valuable for the direct functional application of supramolecular cage in the future.(2)In Chapter 3,two functional groups were introduced on ligand 3b to form four ligands,which were assembled with metallic zinc to obtain a cubic truncated octahedral supramolecule consisting of 24 metals and 72 anions.Supramolecule 4c was tentatively identified as the designed supramolecular conformation by MS characterization,but more proof data need to be obtained next using more time due to the high difficulty of purification of the complex composition.The supramolecular conformations of supramolecules 4d,4e and4 f were confirmed by NMR and MS as the expected designed cubic truncated octahedra.Using the function of porphyrins,the molecular cages were given applicability,making the cubic truncated octahedral molecular cages very promising in many fields such as photosynthesis,artificial development of solar energy,medicine,molecular electronics,and photochemistry.Then the aldehyde group was introduced into the molecular cage,and the aldehyde group can react with the amino group to form Schiff base,which is a simple reaction condition and easy to operate,and can save a lot of experimental time.These two methods of introducing modification sites into supramolecular cages provide a theoretical basis for the subsequent functionalisation of supramolecular cages.While obtaining large domain-limited cavities,the internal cavities were modifiably modified with multiple functional groups capable of bonding substrates or catalytic centers with non-covalent interactions to obtain novel liganded supramolecular artificial enzymes.The results are expected to broaden the field of artificial enzyme simulation,provide new ideas for the application of supramolecules,and provide new methods for efficient artificial enzyme catalysis.