| Stimuli responsive molecules can respond to external stimuli,like anions,temperature and light,et al.Recently,due to their good performance and development space,more and more attention has been paid to them.In the past few years,they have been applied in many areas,like ions detection,photoelectric functional materials,and environmental monitoring,et al.Because of the disadvantage of some anion probs,like poor selectivity,low efficiency and rarely being used in pure water,anion probes based on small organic molecules developed more slowly than cation probes.So it has great practical value to prepare anion probes with appropriate sites for anion recognition and mechanism to obtain excellent property.In addition,traditional thermometer can not be used in micro field and harsh environment.In this case,thermometers based on molecular level become very important.It is a good choice to use AIE property of small organic molecules to prepare this kind of thermometer.Otherwise,photo-responsive compounds can undergo physical and chemical changes after the UV irridiation.Among them,photoinduced isomerization is one of the most widely studied photochemical reaction.In this thesis,anions,temperature and photo reponse systems were constructed and their properties were also studied.Firstly,two novel Schiff base type receptors containing phenol hydroxyl group(1)or methoxy group(2)were designed and synthesized.The receptor 1 with phenol hydroxyl group exhibited different colorimetric and fluorimetric responses to fluoride ions and cyanide ions.In the colorimetric channel,the colorless solution turned to yellow towards F￣,but red in the presence of CN￣.In the fluorimetric channel,the nonluminous solution showed different “turn-on” response to F￣ and CN￣,respectively.The distinguishing responses of receptor 1 to the two anions in dual channels were attributed to the disparate interaction mechanisms.F￣ was detected through the formation of hydrogen bonds and the subsequent deprotonation process.CN￣ initially formed hydrogen bonds and then it attacked the receptor via a nucleophilic addition reaction.In contrast,the receptor 2 with methoxy group only showed remarkable color change from colorless to yellow towards F￣.These results proved that the phenol hydroxyl group played an important role in the discriminating detection of F￣ and CN￣.This part of work provided a new way for the design and synthesis of “one to more” anion probes.Secondly,the anion recognition properties of 1 and 2 of the above part were investigated in the semi aquoues system(THF/H2 O = 6: 4).The molecule 1 showed "OFF-ON" fluorescence changes to CN￣,while compound 2 completely lost the ability of anion recognition.The phenomenon induced by the addition of OH￣ to 1 was nearly the same as that of CN￣.And combining with the anion response behavior of 2 and 4,it was believed that there was a deproton interaction between 1 and CN￣.The hydroxyl group and amide group in the structure of 1 played a very important role through the fluorescence and colorimetric channel respectively in the CN￣ detection process.Otherwise,the value of pH and the fractions of water(fw)in the mixed solvent both affect the detection of CN￣.It showed the best detection property,when the value of pH was 5 and the fw was 40%.Then a new amphiphilic polymer P1 was obtained by the copolymerazition of NIPAM and molecule 1.It could also work as a fluorescence “turn on” CN￣ probe.The detection process can be returned back by copper ions.Thirdly,we prepared a kind of cyanostyrene derivative A2 with nitro group.The compound could selectively and rapidly(1 minute)detect cyanide anions by naked eyes,without interference from other anions.The detection limit is about 1 ppb.The results of 1H NMR,IR and MS revealed that CN￣ firstly attacked the C=C double bond of A2 and a new compound was obtained.Then this new compound was oxidized,and an oxidation product appeared.Finally,a test paper was made of this effective and sensitive probe to detect CN￣.In addition,A2 also has photoisomerization property.It could respond to UV light and undergo changes in the UV-absorption spectrum.The maximum absorption band blue shifted with its intensity decrease.According to the results of 1H NMR,after the UV irradiation,about 56.52% of the original Z isomers of A2 transformed into E isomer,when they were at photostationary state.In a word,this work has made contribution to the development of cyanostyrene derivatives in novel area,and also provided a direction for the design of new CN￣ probes.At last,two kinds of cyanostilbene derivatives A1 and M5 were synthesized.We studied their photoinduced isomerization,supermolecule self-assembly behavior and spectral properties.The results showed that both of them showed response to UV light at dissolved state and aggregated state.They both exhibited "OFF-ON" fluorescence changes in THF,during the whole photoisomerization process.Otherwise,in the mixture solvent(THF/H2 O = 5: 95),M5 showed AIE property,while A1 was still nonluminous.In micro-field,dendritic morphology and nanofiber were formed respectively through the self-assemble of A1 and M5.But all of them dissociated into nanoparticles after the irradiation.Due to the AIE property and the change of isomer,M5 showed “ON-OFF-ON” transformation in fluorescence channel upon the irradiation,while A1 exhited "OFF-ON" fluorescence changes.A novel amphiphilic polymer P5 was obtained by the polymerization between M5 and NIPAM.It could responsed to temperature and UV light.It could respond to temperature in a wide range(15 – 70 ℃).When the temperature was between 15 ℃ and 35 ℃,the intensity of the fluorescent peak increased with the increase of temperature.But when the temperature exceeded 35 ℃ and under 70 ℃,the fluorescence emission became weak with the increase of temperature.Moreover,due to the incompact aggregation,it exhibited very weak fluorescence emission at 425 nm at room temperature.However,the intensity of fluorescent peak enhanced obviously,and blue shifted to 382 nm after the irradiation by UV light.In brief,this work made a contribution to the study of AIE properties and photoisomerization behavior of cyanostilbene derivatives,and offered a new idea for the application of such compounds in intelligent polymer materials. |
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