Preparation And Study Of Stimuli-responsive Fluorescent Supramolecular Polymers Based On Pillar[5]arenes

Aggregation-Induced-Emission（AIE）materials have become a hot research topic in the field of functional materials in the recent 20 years,due to their unique luminescent property and the outstanding pohotphysical property in the solid state,and they are not only applied in light-emitting devices,dyestuff,anti-counterfeit field,but also provides new ideas and opportunities for the development of biology,medicine and life science.In the nowadays of diversified demands and interdisciplinarity,single functional fluorescent materials are harder and harder to satisfy people’s increasing needs.Ingenious design and synthesis of intelligent fluorescent material system possessing unique photophysical property has become one of the most meaningful research topics.Supramolecular polymers are the high molecular weight aggregates assemblesd by repeating units based on the noncovalent bonds.The dynamic reversibility of noncovalent bond provides supramolecular polymer with stimulus-responsive property.Introduced AIE molecules into supramolecular polymer system,the photophysical property can be guaranteed,and the luminescent property can be controlled by the process of stimulus-response,which makes AIE-supramolecular polymer become an ideal kind of smart fluorescent materials.Based on these,we choose pillar[5]arenes as the supramolecular macrocyclic molecules,diselenium bonds as the stimuli-responsive blocks and the tetraphenylethylene derivatives as the AIE-active fluorescent guests to construct two different kind of stimuli-responsive fluorescent supramolecular polymeric systems.Moreover,we explored the application of these two fluorescent supramolecular polymeric systems in the field of sensor and detection.The main research contents of this paper are as follows:In the first part,we use diselenium-bridged pillar[5]arenes dimer as the supramolecular host,and ingeniously synthesized an tetraphenylethylene（TPE）derivative bearing two imidazole terminal binding sites（TPE-（Im）₂）as the“double-arm”guest.Based on the host-guest interaction between TPE-Im₂ and SeSe-（P5）₂,the viscous fluorescent supramolecular polymers with stimuli-responsive properties were obtained.And then we studied on the fluorescent property during the self-assembly process and the fluorescent property changes during the different depolymerization process upon two kinds of stimuli（dithiothreitol,adiponitrile）.The results show that the existence of these two kinds of stimuli can make the fluorescence intensity of the materials increase in different degree,which realizes the sensitive detection of these two kinds of stimuli.In the second part,we further designed a kind of tetrastyrene derivate modified by four imidazole terminal binding sites,（TPE-（Im）₄）,and used it as the“quadruple-arm”guest.Three-dimensional structure network can be formed through the host-guest interactions between TPE-（Im）₄ and SeSe-（P5）.Furthermore,fluorescent supramolecular gel can be successfully obtained by the optimization of experimental conditions.The results illustrate that the aggregation-state structure of the supramolecular gel results in distinctly fluorescence intensity increasing phenomenon,which is totally different from the fluorescent property of linear fluorescent supramolecular polymer.And we further study on the thermal response property of this kind of fluorescent supramolecular gel,the result shows that the fluorescence can be quenched by increasing the temperature,which can be used to construct the fluorescence gel with thermal response.