Chiral Nanostructures Of A Benzoate Ester Molecules:Fabrication And Applicated In Asymmetric Catalysis

Exploring chirality at the supramolecular level is very important for revealing the chirality origin in the nature,and the supramolecular chirality has caused more and more attentions.To develop new building blocks of chiral assemblies with a given structure character is of significance for exploring the assembly mechanism of chiral structures and creating functional chiral material with predictable properties.In this thesis,we reported a new building blocks of chiral assemblies,a benzoate ester molecule,4,6,8,10,12,14,16,18,20,22,24,26-dodecamethylnonacosane-2,28-diyl dibenzoate(DMNDB).As found,left-handed nanowires could be constructed by the self-assembly of DMNDB molecules in THF/water mixed solvents,where the misaligned J-aggregation of DMNDB molecules took placed and was induced by the directional ?-? stacking forces and electrostatic repulsion presented among molecular chains.In alcohol/water mixtures,these twisted nanowires would immobilize solvent to form gels,which is caused by the cross-linkage among nanowires due to the absence of the electrostatic repulsion and presence of the hydrogen bonding interactions on the surface.With high alcohol usage(such as 60%),the left-handed nanowires could transform into right-haned nanofibers,which should be ascribed to the arrangement change from the loose J-aggregation to the compact H-type stacking of DMNDB molecules driven by H-bonding and ?-? stacking interactions among the interior molecules.DMNDB as a simple benzoate ester molecule could form chiral assemblies just by mixing solvents,which might provide better understanding for the supramolecular chiralityBecause the structure of DMNDB supramolecular system is too simple,DMNDB supramolecular assemblies have limitations in practical applications because of the quite simple structure of DMNDB molecule.In order to achieve the wide application of materials in the field of chirality,the functional aniline tetramers(TANI)are added to the system to form DMNDB/TANI composite chiral nanostructures(left-handed nanowires and right-handed chiral gels).Two chiral composite materials were used to resolve racemic substances(including camphorsulfonic acid,tryptophan,alanine,phenylalanine,glutamic acid),showing the potential for enantioselective separation.Gold nanoparticles are supported on the surface of DMNDB/TANI composites as catalysts,and they also show a certain effect in the selective oxidation of chiral dopa.It can be seen that supramolecular chiral structures obtained based on the self-assembly of DMNDB molecules have obvious advantages in terms of raw material acquisition,preparation methods,and environmental impact.Moreover,these spiral chiral nanomaterials have the characteristics of uniform micromorphology,strong chiral signals and good environmental stability.