Construction And Properties Of Cyanostilbene-based Supramolecular Polymers

Supramolecular chemistry,or "chemistry beyond molecules",is a subject based on non-covalent interactions.Supramolecular polymers refer to ordered and regular structures arising out of non-covalent interactions between molecules.Supramolecular polymers present incomparable dynamic reversibility of traditional polymers.Therefore,they can be used for the development of self-healing materials,self-adaptation materials,shape memory materials,multiple responses materials and so on.Nowadays,how to precisely regulate the structure and function of supramolecular polymers is still a challenge for the scientific community.Since changing the molecular skeleton structure causes discrepancies in intermolecular interactions,a series of supramolecular materials with different morphologies and functions and functions can be obtained by constructing monomer molecules with different skeleton structures.Due to its electron-deficient properties and AIE/AIEE effects,the cyanostilbene motif is concerned as an interesting candidate for supramolecular polymers.In this dissertation,we chose cyanostilbenes as a fluorescent moiety to construct novel rod-like and propeller-like monomers.Through the "bottom-up" self-assembly strategy,supramolecular polymers with different functions were obtained.In the first part,we designed a novel type of rod-like supramolecular monomer baseed on α-dicyanostyrene motif.Then we investigated the behavior of supramolecular polymers though UV,fluorescence and CD spectroscopy.The results show that the supramolecular monomers assemble into regular and ordered one-dimensional helical nanofibers via nucleation-elongation mechanism.Due to the AIEE effect of α-dicyanostyrene,the polymers present dual amplification of fluorescence emission and chirality signals in low concentration MCH solution.Therefore,the resultant supramolecular polymers exhibit excellent circularly polarized luminescence properties without CD artifacts derived from macroscopic alignments.In the second part,a novel D-π-A supramolecular system has been designed and synthesized.For the designed supramolecular monomer,triphenylamine serves as the π-aromatic core.Thiophene and N-(1-phenylethyl)benzamide linkages are attached on ends of triphenylamine.Through the spectroscopic study and crystal analysis of the model small molecule,this D-π-A molecular has been proved to have intramolecular charge transfer effect and symmetrical non planar propeller-like structure.On this basis,we explored the application of this D-π-A supramolecular system in the detection of nitroaromatic compounds.Benefiting from the AIEE effect of supramolecular polymers,the photoresponse sensitivity of supramolecular polymers to 2,6-dinitrotoluene is significantly higher than that of monomers,which would benefit for the design of optically responsive materials.