Construction Of Supramolecules With Transmembrane Function By Molecule Folding And Self-assembly

Self-assembly phenomena exist widely in living systems,such as the formation of cell membranes and folding of proteins,which all occur under the influence of various non-covalent forces.After decades of development to mimic the structure and properties of natural living systems,chemists have developed the ability to give molecules specific functions through structural preorganization.Among them,foldamers have become one of the emerging research fields in supramolecular chemistry by virtue of their unique properties.Foldamers have the advantages of stable structure,strong predictability,good modifiability,etc.,and can be used to construct the basic element to simulate the function of natural proteins.This paper aims to simulate the transport function of natural channel proteins by artificial folding bodies,and successfully construct supramolecular structures with transmembrane capability by using the supramolecular strategy of molecular folding and self-assembly,and study the morphology and transport properties of the supramolecular assembly.The experimental results proved the unique spatial effects of the artificial folding body and the importance of the terminal group in the ion transport system.Two different proton transport mechanisms were revealed,which enriched the structural model of the artificial ion transport system.1.Macrocyclic aromatic amides self-stacking to construct transmembrane supramoleculesA new quinoline monomer primitive was designed and synthesized,and a folding structure with matching size was formed through reasonable molecular design.By means of the unique spatial limiting effect of the foldamer,the intramolecular amine transesterification reaction was realized to construct a macrocycle structure connected by amide bonds.The new structure brings new properties and functions.The aromatic amide macrocycle is easy to accumulate on the membrane due to the extremely strongπ-π interaction between molecules,and the supramolecular assembly formed by the accumulation has the ability of ion transport.The planar conformation of the macroring in space is proved by theoretical simulation and NOESY experiment.On this basis,the molecular folding strategy is validated by reference molecules,and a novel ring synthesis method is developed.The macroring of aromatic amide can self-stack to form supramolecular polymer with transmembrane ability and realize ion transport through the gaps between the rod-like assemblers.This pattern of ion transport through multiple columnar aggregates is similar to that of natural ion channel proteins,which provides a good model for simulating the structure and function of natural biomolecules by means of supramolecular assemblers.2.Construction of transmembrane supramolecular polymers by helical elementsThree kinds of folding molecules with different terminal functional groups were synthesized by using the same aromatic spiral skeleton,and it was determined that the terminal functional groups have an important effect on the transport capacity of the system.By introducing UPy units at both ends of the helical skeleton to modify the functional groups,the assembly mode of helical oligomers can be changed under the action of quadruple hydrogen bond,and supramolecular polymers with transmembrane function can be constructed.In our system,helical oligomers with amino functional groups can carry protons with amino functional groups to achieve proton transmembrane transport by proton gradient;The supramolecular polymers constructed by helical elements can transfer protons across membranes by means of waterlines through the gaps between the assemblers.In addition,the ion transport properties of supramolecular polymers E and F,which have similar structures,are significantly different.Such changes in ion selectivity may be caused by differences in the arrangement order and quantity of ether bonds and carbonyl oxygen in the skeleton structure of monomer molecules.This finding can provide experience and reference for the structural design of ion selective transport simulating natural channel proteins.