Supramolecular Chirality Manipulation And Applications Of Amino Acid Derivatives

Chirality is a universal phenomenon in nature,and therefore the studies of the origin and rational control of chirality are closely related to the explanation of the evolution of life and the development of chiral supramolecular materials.Amino acids,as one of the simplest small biological molecules,have shown natural superiority in both structure and properties in the fields of biomimetic materials and wearable soft materials.Using co-assembly strategy or solvent effect to control the supramolecular chiral characteristics caused by the point chirality of amino acid derivatives has become the guiding ideology of the preparation of intelligent supramolecular chiral materials.In this thesis,a series of amino acid derivatives are designed as the base molecules and their supramolecular chiral characteristics are regulated by effective measures,such as halogenation effect and solvent effect,to construct flexible supramolecular chiral systems and investigate their unique chiral optical characteristics.The main research contents of the thesis are as follows:1.We realized the construction of artificial single/double helix structures directly based on simple derivatives of amino acids(ferrocenyl phenylalanine).The chirality of the superhelical structures were analyzed by single crystal structures and circular dichroism spectroscopy.The constructed motifs are orthogonally driven by intermolecular hydrogen bonding bonds and CHπ interactions leading to one-dimensional helical stacking,and the helical orientation is determined by molecular point chirality.The superhelical structures were retained by selfassembly in the aqueous phase.The multi-component co-assembly behaviors were also investigated while the hydrogen-bonding acceptor molecule benzimidazole derivative TBIB and charge-transfer acceptor TCNQ were introduced.And the transfer and inversion of chiral features of the small-molecule acceptor were demonstrated by circular dichroism spectroscopy,electron microscopy and 1H NMR.2.N-terminal aromatic amino acids with different substituted halogen atoms at pphenylalanine residues self-assembled into one-dimensional fibrous structures.Halogenation induced the emergence of macroscopic chirality regardless of halogen properties like electronegativity,generating exclusive homochiral helical structures.On the basis of ECD and solid-state X-ray structures,multiple chiral packing modalities including H-bonds and halogen bonds were determined,affording 21 supramolecular tilt chirality and propeller chirality respectively.The molecular dynamics simulation results are in good agreement with the experimentally chiral morphology.Halogenation was also reflected in the luminescent properties,whereby FH,FF,and FCl afforded blue CPL while FBr features a cyan color of CPL3.We present unprecedented hydration-driven chiral molecular rotor systems based on the Herrick’s conformation of N-terminated ferrocene diamino acids.In solid and solution phases,double intramolecular H-bonds fixed the orientation of amino acids to allow for chirality transfer to ferrocene,which demonstrated significant dependence on solvent environments.Water intercalation aroused the destruction of pristine H-bonds between adjacent amino acids and the formation of new H-bonds,driving the movement of diamino acid arms with increased dihedral angles.Water dynamics in molecular switching behavior were illustrated by proton NMR and DFT calculations that indicated the intercalation of water via multiple H-bonds.Hydration-triggered molecular movement caused pronounced variations to the induced axial chirality with switchable chiroptical responses.This work discloses the crucial role of water in chiral switchable molecular movement behavior,and provides a promising protocol for fabricating external field-responsive chiral materials.