Design Of Chiral Structures And Chiral Regulation Mechanism Based On Conjugated Amino Acid Derivatives

Chirality has a universal characteristic,which is a fundamental attribute of the nature.With the development of supramolecular chemistry and molecular assembly,the study of supramolecular chirality has gradually penetrated into every field of science.Amino acid derivatives have the characteristics of easy modification,economy and good biocompatibility,making them widely used in the field of chiral materials.Based on the design and synthesis of conjugated amino acid derivatives,this paper utilizes non-covalent interactions such as hydrogen bonds,halogen bonds,π-π stacking,van der Waals forces and electrostatic interactions to regulate the assembly of various chiral materials,and studies their dynamic assembly processes.The main research content is divided into the following two aspects:1.Design,preparation and properties of phenylalanine derivatives assembled chiral materials regulated by X…X halogen bonds.In this work,a variety of pyrene conjugated phenylalanine derivatives(PF-X,X=H,F,Cl,Br,I)were designed and synthesized.The intramolecular pyrene group can effectively enhance π-π stacking and promote the formation of X…X halogen bonds.It has been found that in the PF-F assembly system,fluorine atoms participated in the formation of hydrogen bonds,and under the driving of hydrogen bonds,the assembly produced left-handedness supramolecular chiral helices.In the assembly systems of PF-Cl,PF-Br and PF-I,X…X halogen bonds were formed,which can drive the formation of supramolecular helix with right-handedness.Special molecular geometric structures and the synergistic effect of various non-covalent interactions contribute to the formation and stability of weak X…X halogen bonds.Hydrogen bonds and X…X halogen bonds can drive the assembly system to form chiral helical structures with opposite helical directions,and produce opposite circular polarization luminescence(CPL),which can achieve a luminescence dissymmetry factor(glum)of order of 10-2.In addition,co-assembly cal drive the evolution of nano assemblies from nanotubes,nanorods to nano helical fibers.This work was the first to reveal the important role of weak X…X halogen bonds in the formation and evolution of supramolecular chiral helices,which can be used to regulate the chiral optical properties of conjugated amino acid derivatives and prepare single component and multi-component chiral assembly materials.2.Preparation and properties of conjugated amino acid derivatives regulated by theβ-folding strategy.In this work,nine conjugated amino acid derivatives were designed and synthesized.Research has found that β-folding strategies can induce the distortion of the aryl,which driven the generation of the aryl chirality and directional regulations of the aryl chirality of N-Ala was realized by a solvent strategy.Under the influence of CH…π,steric hindrance effects and hydrogen bonds,the plane of polycyclic aryl group was distorted and showed chiral signals.Its aryl chirality was related to the chirality of amino acids.X-ray diffraction,circular dichroism(CD),CPL and theoretical calculations were used to further confirm that β-folding structures and different amino acid substituents played a key role in the chiral generation,transfer and amplification.This work revealed that β-folding strategies can be widely applied to polycyclic aromatic hydrocarbons with diverse functions,which provided a promising strategy for tuning and controlling the aryl chirality with adaptive chiral responses.