Study On Construction And Properties Of Functional Cyclic Peptide Assemblies

In organic molecular self-assembly systems,peptide molecules containing natural amino acids have obvious advantages,such as flexible amino acid sequence design,easy regulation,convenient synthesis,and good biocompatibility.The organic nanomaterials formed by the self-assembly of polypeptide molecules,especially cyclic peptide nanotubes,have the advantage that other nanotubes cannot be replaced.Due to these advantages,they can be widely used in chemistry,materials science,biological materials and medicine.Therefore,the self-assembly of polypeptide molecules has become a research hotspot in recent years.With a large rigid planar sebimide derivative,there are large-interactions between the molecules.It has a high charge transport capacity and light,thermal and chemical stability.It has strong absorption and emission from the visible light region to the infrared light region.It is a kind of organic photoelectric material with peculiar photophysical and photochemical properties.If asymmetric perylenediimide is used as a functional side chain and the cyclic peptide is linked through a covalent bond,the cyclic peptide is modified to promote the cyclic peptide not only through side chain interactions but also hydrogen bond interactions on the backbone.Moreover,the cyclopeptide assembly has better photoelectric properties.Based on the above ideas,this dissertation studies the synthesis and self-assembly of functional cyclic peptide assemblies.First of all,according to the basic principles of cyclic peptide nanotube design,combined with the related research of Cyclopeptide by the research group,With D-leucine,L-leucine,L-alanine and L-lysine as the basic structural units,D,L-?-amino acids are alternately linked to form the basic skeleton of cyclooctapeptide;Then,the two functional cyclic peptide assemblies were designed and constructed by linking the lysine to the asymmetrical perylenediimide side chain.In the liquid phase,the Boc-strategy was used.The one-by-one linking method was combined with the fragment convergent method to successfully synthesize the cyclic peptide assembly.The synthesis methods of related intermediates and target molecules were also studied.The self-assembly of functional cyclic peptides was further studied.The assemblies were characterized by SEM and TEM,respectively,and their optical properties were further tested by a fluorescence photometer.The effect of functional side chain interactions on the self-assembly and optical properties of cyclic peptides was investigated.Through the study of the assembly,it was found that the tubular structure was not obtained,so its side chain was expanded.The cholesteryl chloride in the gel factor is used as a side chain,and it is connected with the polypeptide,which can promote the formation of a gel under certain conditions.In this paper,a tripeptide containing a gel factor was synthesized by linking it with a chain tripeptide.It was observed whether or not it could form a gel in different solvents by solvent adjustment method.The result was found in nitromethane,n-heptane,petroleum ether,and methanol water.The gel formed in the mixture.It was characterized by SEM and TEM,and the assembly of tubular structure was obtained.