Synthesis,Characterization And Stimulus Responsive Characteristics Of Compounds Containing Spiropyran Groups

Spiropyran derivatives showing characteristics of rapid light response,acid-base response,p H response,temperature response and force response have attracted abundant attention for their wide applications in optical data storage,chemical sensors,displays,security ink,anticounterfeiting,bioimaging,optical shutters,and photoswitchable molecular devices.In recent years,most of the reported fluorescent switches with spiropyran（SP）units work only in solution and very few were reported in the solid state.The main battle for the solid-state photochromism of spiropyrane is their strong intermolecular accumulation.Its isomerization requires a large amount of free volume to complete the response from SP to MC form.Therefore,in this paper,the free volume in the system is increased by highly twisted TPE molecules and introduced into the side-chain of polymers,and its AIE performance,photochromic performance,acid-base response characteristics and material surface wettability are carried out.1、We covalently linked TPE with two SPs at the N-site through spacers to obtain compounds of SP-TPEm（m=4,6）,the monomers’chemical structures is confirmed by¹H NMR,¹C NMR and MALDI-TOF.Through the fluorescence emission spectra test of different H₂O/THF content,it is proved that both target small molecules have the characteristics of aggregation-induced emission;The UV spectra test before and after the 365nm UV lamp illumination and the intuitive sample discoloration test show that the two target small molecules have photochromic properties in the state of solution or solid powder;Infrared spectra test before and after acid-base gas stimulation show that the target products have acid-base response characteristics;The water contact angle test before and after illumination shows that the target molecule can realize the transition from hydrophobic to hydrophilic.2、We successfully introduced the spiropyran structure into the side group of vinyl terephthalic acid through the N-position connection,and copolymerized with MMA through radical polymerization and obtained our target polymers P10,P20,P30.The chemical structures of monomers and polymers were confirmed by ¹H NMR and MALDI-TOF and GPC.TGA tests exhibited that all three polymers show good thermal stabilities and the decomposition temperature with 5%weight loss was above310℃.After UV irradiation at 365 nm,a new absorption peak at about 590 nm appeared in the absorption spectra of polymer solutions,and the solutions changed from colorless to deep blue;a new absorption peak at about 570 nm emerged in the film absorption spectra of the polymers,and the polymer powders changed from white to brick red.In addition,the absorption intensity at the new absorption peak was proportional to the copolymerization ratio of spiropyran monomer.It can be seen that our target polymer realized photochromism in the solid state or powder.In addition,the series of polymers exhibited solid-state acid-base response characteristics.