Research In Cyclodextrin Derivatives-based Supramolecular Assemblies And Their Photoswitchable Behaviors

Due to abroad applications in chemistry,biological,material science,environment and informational science,supramolecular chemisty has been drawn increasing attention since its inception,in which molecular recognation and molecular assembly are the hot spots.how to realize the construction of high-ordered nanoassemblies bearing special functionsto mimic the functional aggregations in nature is one of themost important goals for supramolecular chemists.In this thesis,novel supramolecular systems were constructed by cyclodextrin derivatives and/or azobenzene derivatives,and the corresponding propertives and functions were further investigated.The specific contents are as follows:(1)The general aspect of supramolecular chemistry and cyclodextrin were descripted in brief.The new progress and important achievements on ionic cyclodextrin derivatives and azobenzene derivatives in supramolecular chemistry were reviewed.(2)A series of carboxyl-modified cyclodextrin were syntheiszed and applied to investigate their induced aggregation towards amphiphilic cationic molecule.The results indicated multi-charge and electrostatic interaction played key roles in the molecular induced aggregation.Based on these disscoveries,a stable supramolecular nanoparticle was fabricated to encapsulate model drugs for the controlled released.(3)The azobenzene-bridged bis(permethyl-?-cyclodextrrin)was designed and synthesized viaclick reaction.Taking advantage of the conformational difference between its trans-and cis-isomer,the assembly morphology of the aggregation with amphiphilic porphyrin derivative turned to nanotube and sphere nanomicelle respectively via second assembly.Crucially,it was thefirst time to realized the interconvension betweeen two obviously different supamolecular assemblies upon photo-irradiation.(4)The azobenzene-bridged bis(permethyl-?-cyclodextrrin)was synthesized via clilk reaction.The conformation of its trans-and cis-isomer in different solutions were further investigated,thereafter we investigated their binding behaviors and assembly behaviors toward tetracarboxyphenylporphyrin.Meanwhile,a photoswitchable nanoparticle and nanowire was successfully constructed.(5)The adamantanyl-modified diphenylalanine and azobenzene-bridged bis(?-cyclodextrrin)were designed and synthesized.The adamantanyl-modified diphenylalanine self-assembled into nanofibers due to the assembly character of diphenylalanine.Taking the advantage of the strong binding affinity between the amantanyl group and the ?-cyclodextrin cavity as well as the conformational difference of azobenzene derivative;the nanofiber turned to nanotube and nanosheet with addition of cis-and trans-isomer respectively.Furthermore,these two kinds of dimensional supramolecular assemblies could reversibly and repeatedly interconvert to each other with irradiation at different wavelengths(6)A photo-stimuli responsive pseudo[2]rotaxane was successfully constructed by the azobenzne-bridged bis-ferrocene derivative and ?-cyclodextrin,thereafter a pseudo[4]rotaxane was successfully obtainedupon the addition oftwice of cucurbit[7]urils due to the ultrahigh binding affinity between cucurbit[7]uril and ferrocene.Interestingly,the obtained pseudo[4]rotaxane displayed high stability in the tough environment such as hightemperature and UV irradiation,thus it be regarded as a [2]rotaxane.Based on these results,it could be expected that the macrocycle molecules worked as “stoppers” instead of “rings” connected to axle via noncovalent interactions will broaden the constructional strategy of rotaxane.