The Research On The Stimuli-responsive Supramolecular Systems Constructed From Azobenzene Derivatives

Controllable construction of light-stimulated-responsive supramolecular systems by molecular recognition and molecular assembly is one of the most fascinating hotspots in supramolecular chemistry and materials science.Benefiting from the significant structural differences between cis-/trans-isomers,azobenzene has been widely utilized for constructing photo-responsive supramolecular systems.Based on this,a series of novel azobenzene derivatives were designed and synthesized,and three types of stimuli-responsive supramolecular systems were prepared by molecular assembly and host-guest bonding.The main contents are as follows:1.The supramolecular chemistry and supramolecular gels are briefly introduced,and the latest research results of azobenzene derivatives in supramolecular gels and their host-guest recognition with cucurbituril are reviewed.2.Azobenzene-bridged D/L-tryptophan enantiomers were designed and synthesized,and gluconolactone-driven chiral supramolecular hydrogels were prepared.The gel properties,driving force and coagulation process were studied in detail.The stimuli-responsive behavior of the above supramolecular gels was further investigated.The research results show that the above supramolecular gels cannot undergo phase transition under light stimulation,but the azobenzene reductase mimetic enzyme(sodium hydrosulfite)can induce them undergo gel-solution transition.3.D/L-phenylalanine-modified azobenzene derivatives were designed and synthesized and their photoisomerization behaviors were investigated.Subsequently,the host-guest bonding behavior with vinylpyridinium salt and cucurbit[8]uril was studied in detail,and a ternary composite system was successfully constructed.Utilizing the configuration and bonding differences of cis-/trans-isomers of azobenzene,the above-mentioned cis-/trans-isomers of azobenzene make the composite system of vinylpyridinium salt and cucurbit[8]uril show a significant difference in fluorescence emission.This work provides a preliminary model for photo-controlled fluorescence emission.4.Two azobenzene-derived pyridinium salts and bromophenylpyridinium salts were designed and synthesized,and their host-guest bonding behaviors with cucurbit[8]uril were investigated.Based on these,two types of ternary complex systems were successfully constructed.Subsequently,the reversible regulation of the fluorescence emission of bromophenylpyridinium salts was realized by controlling their photoisomerization of azobenzene between their cis-/trans-forms,which provided a theoretical basis for the construction of new light-regulated fluorescent materials.