Constructions And Reversible Behaviors Of Photo-Responsive Supramolecular Assemblies

Construction of functional supramolecular assemblies based on the noncovalent bonding interactions between host and guest molecules are still an important issue of supramolecular chemistry.Meanwhile,integrating the photo-responsive elements into the hosts or guests is an efficient strategy to construct photo-controlled functional supramolecular materials.Herein,we have designed and synthesized some photo-switched hosts and guests,which are further used to construct a series of photo-responsive supramolecular asemblies sustained by the host-guest interactions.Furthermore,their switchable self-assembly behaviors under light irradiation or heating have been detailly investigated.The specific contents are as following:(1)The brief overview of supramolecular chemistry is introduced.Some representative reports on crown ethers,cucurbiturils,dynamic cyclophanes as well as photochromic molecules are reviewed.(2)A semi-rigid photo-and thermal-responsive tetracationic organic cyclophane has been synthesized,in which the configurations can be reversibly converted between (EE)-and(EZ)-forms by alternating blue light irradiation and heating.Interestingly,both the?-electron-rich and?-electron-deficient guest molecules can be reversibly released and bound by irradiation and heating in alternating fashion.(3)A two-stage assembled photoluminescence supramolecular assembly displays multicolor fluorescence outputs in an in-situ phototuning manner.Upon complexed with cucurbit[8]uril,the fluorescence of diarylethene guest undergo obvious red shift and enhancement.Significantly,the fluorescence of resulting ternary assembly can be changed efficiently from yellow to blue upon ultraviolet light irradiation.Pure white light emission can be realized expediently in the luminescence color conversion process.(4)A photo-switched[3]pseudorotaxane is constructed from diarylethene derivative and[Ru(bpy)₃]²⁺complex mediated by noncovalent association of dialkylammonium with dibenzo-24-crown-8.The fluorescence of resulting [3]pseudorotaxane can be efficiently and reversibly switched on/off by light irradiation.Significantly,this supramolecular assembly is further utilized as photo-erasable fluorescence ink.(5)Three different water soluble macrocycles have been employed as the modulater to control topological features of bipyridinium modified cholesterol derivative.Benefiting from the simple and efficient host-guest strategy,a variety of morphologically interesting supramolecular aggregates,like nanohelix,nanofiber and nanosphere have been expediently constructed.