Synthesis And Self-Assembly Of Rigid-Flexible Block Molecules And Their Derivatives Based On Pentaphenyl And Pentabipyridine

Rigid-flexible block molecule is a molecule composed of a rigid part and a flexible part.Multiple non-covalent forces between rigid-flexible block molecules drive their self-assembly to form various nanoaggregates.The supramolecular aggregates formed by the self-assembly of rigid-flexible block molecules have broad application potential in the fields of optoelectronic materials,catalysis,controlled drug release,drug delivery,and biomimetic materials.In this thesis,rigid-flexible block molecules of A(A1 and A2),B(B1 and B2),C(C1 and C2)and D(D1 and D2)based on pentaphenyl and pentadipyridine were designed and synthesized.The flexible chains of molecule 1 are all polyethylene oxides with a degree of polymerization of 6,and the flexible chains of molecule 2 are all dendritic polyethylene oxides.The rigid part of the molecule consists of pentaphenyl and pentabipyridine and their derivatives.The flexible chains are all connected in the center of the rigid part.There is a molecular-structure connection between these molecules,some with the same rigid aromatic conjugated moiety and some with the same flexible chain.Using atomic force microscopy(AFM),transmission electron microscopy(TEM),ultraviolet absorption spectroscopy(UV)and fluorescence emission spectroscopy(FL)and other testing methods,this thesis studies in detail the difference in molecular structure and the effect of acidity on these molecular morphological changes in a mixed solution of water and tetrahydrofuran,and summarize the relationship between its structure and morphology.The results show that for the same rigid aromatic conjugated molecules,the molecular assembly size of linear flexible PEO chain with polymerization degree 6 is larger than that of dendritic flexible PEO chain due to different steric hindrance and intermolecular force.Molecules with the same flexible chain,the B series molecules are compared with the A series,the molecular size of the series is smaller than that of the A series;Compared with the B series,the N atom on the pyridyl group of the C series molecule was methylated with methyl iodide to make it an ionic compound,because the existence of electrostatic repulsion force makes the assembly size of the C series molecule smaller than B series;Compared with the B series,the D series molecules use silver trifluoromethanesulfonate to coordinate with the pyridyl group to obtain a high molecular weight coordination polymer,so that the size of the D series polymer assembly is larger than that of the B series.We also found that when p H=3.0,the pyridyl group of the rigid conjugated part of the B-series molecules would be protonated,and the electrostatic repulsion would make the assembly size of the B-series molecules significantly smaller.Therefore,in this thesis,by designing a series of molecules to precisely control the aqueous assembly morphology of four series of molecules based on pentphenyl and pentadipyridine.It provides a solid theoretical basis for further study of the target molecular transport,ion sensing and spectroscopic properties of these molecules.