Controllable Chirality Of Co-assembly Systems Based On Cyanostilbene Derivatives

Chirality is closely related to the structures and functions of living organisms in nature,for example,the left-handed Z-DNA and right-handed B-DNA with different functions in cells.Besides,some misfolding peptides with inverted chirality may induce some diseases.Therefore,realizing controllable chirality in chiroptical materials remains a key problem.Supramolecular assembly based on non-covalent bond interactions has appealed the widespread attention on account of simple preparation without complex synthesis.Since the weak interaction between non-covalent bonds is sensitive to external stimuli,the chiroptical properties of supramolecular systems can be effectively regulated by different stimuli.Thus,realizing controllable chirality is beneficial to the understanding of special chiral phenomena in nature,but also provides ideas for the design and synthesis of chiroptical materials.1.In order to explore the effect of light on supramolecular chirality,we synthesized the photoresponsive cyanostilbene derivative and chiral alanine amphiphilic derivative,which could assemble the right-handed entangled fibrous structure in the mixed solvent of methanol and water.After UV radiation,the obvious morphology changes from nanofibers to spheres,accompanied by the disappearance of the supramolecular chiral.Through UV-vis spectra,FL spectra and NMR results,it is showed that UV light leads to the trans-cis,which breaks the carboxylate-pyridine hydrogen bonds and transforms the ordered layered stacking into disordered stacking,resulting to the morphologic transformation and supramolecular chiral regulation.2.To fabricating triple-modulated supramolecular chiral inversion in the assembly system,stoichiometry,cooling rate and metal ions were regulated in co-assembly systems.It is found that changing the stoichiometry can effectively cause supramolecular chiral inversion.The supramolecular handedness can be further inverted bymeans.of altering cooling rate and incorporating metal ions.The mechanism study reveals that the synergistic effect and subtle balance among hydrogen bonds,coordination interactions,and π-π stacking interactions contribute to the chirality inversion.In addition,co-assembly systems also exhibit circularly polarized luminescence properties.This work not only contributes to gain in-depth insights into the understanding of chirality inversion phenomena in the nature,but also sheds light on broadening application of chiroptical materials.