Construction And Application Of Multi-responsive Organic Fluorescent Probe Based On 3-dehydroshikimic Acid Uni

Shikimic acid,as a renewable and environmentally friendly biomass,has been recognized as a promising platform compound,which can be used to produce a variety of bulk chemicals and higher value-added chemicals by non-aromatized routes.Due to its multifunctional structure and synthetic potential,shikimic acid can transfrom into a series of novel compounds under different conditions.To date,shikimic acid has been successfully used in the industrial for the synthesis of the anti-influenza drug Tamiflu.However,the development and application in the field of new functional materials are still in its infancy.Herein,shikimic acid as a renewable biomass-based chemical with multiple functional groups,is used as a platform molecule for the synthesis of a series of novel functional fluorescent probes.Organic small molecule fluorescent probes have unique advantages such as controllable synthesis,modifiable structure,adjustable fluorescence,good biocompatibility,sensitivity and selectivity.Therefore,the photochemical properties of organic fluorescent probes are generally more stable than other types of probes when applied to biological imaging.Additionally,organic fluorescent probes also help to achieve higher fluorophore density and spatial resolution.At present,fluorescent organic small molecule probes have been used in the detection of ions,neutral molecules,biological macromolecules and environmental parameters in biological systems.Therefore,it is of great significance to design organic small molecule fluorescence probes with novel structure and function to detect the changes of relevant parameters in the environment and biological system.Based on（-）-ethyl-3-dehydroshikimiate,herein,we revealed the constructed and applications of fluorescent organic small molecule probes with good selectivity,high sensitivity and strong ability to resist external environmental interference to detect environmental parameters（such as temperature,pressure,polarity,viscosity）and hydrogen sulfide.The specific contents of the study are as follows:（1）A series of aggregation-induced emission（AIE）organic small molecule fluorescence probes were designed and synthesized.These AIE probes could specific response to temperature and pressure changes.In Chapter 2,based on the aromatization reaction of o-aminobenzoic acid with3-dehydroshikimate,15 compounds（a-o）with the key structure of o-carboxyl diaromatic amine（A-O）were obtained from the renewable biomass molecule shikimic acid,and 10 of them showed typical AIE behavior.The fluorescent emission of those AIE dyes can be changed from white to green or blue by changing the substituent groups that may affect the properties of AIE.The fluorescence emission of AIE molecules varies with the change of temperature/pressure,and the change of fluorescence intensity can be used as a quantitative signal of ambient temperature/pressure.Density functional theory calculations revealed the regulatory effect of substituent on the AIE properties of compounds a-o.In addition,organic nanoparticle fluorescence probe（ONFP）based on compound o was prepared and applied to the selective and sensitive detection of arginine in real water.（2）Based on the torsional intramolecular charge transfer（TICT）mechanism,the organic small molecule fluorescence probe QF-OH was constructed to achieve the specific detection of the viscosity and polarity of the system.In Chapter 3,we synthesized a small molecule organic fluorescent probe QF-OH in green chemistry manner.Structurally,the probe QF-OH possesses a C=N bond conjugated D-π-A system which is much easier to be polarized compared with the C=C bond conjugated D-π-A system The fluorescence emission wavelength of probe QF-OH changed remarkably with the variation of solvent polarity and the fluorescence intensity of QF-OH enhanced sharply with the increase of solvent viscosity,which indicate QF-OH could be a promising indicator for the variation of viscosity and polarity.In order to reveal the potential applications of probe QF-OH in monitor the polarity changes of proteins,probe QF-OH was incubation with albumin during thermal denaturation.The experiment results indicated that the polarity of protein would decrease with the increase of temperature during thermal denaturation.In addition,an acetylcholinesterase（Ach E）targeting fluorescent probe named QF-OH-Ach E was designed.After incubation with Ach E,QF-OH could be in situ generated and combined with Ach E to quantify the polarity change of Ach E during the protein aggregation.（3）An organic small molecule fluorescence probe QF-OH-H₂S was designed for the detection of H₂S with low background and high sensitivity based on the intramolecular charge transfer（ICT）mechanism.In Chapter 4,in order to demonstrate the versatility of QF-OH in probe design,a turn-on type fluorescent probe,named QF-OH-H₂S,for H₂S detection was rationally fabricated based on the reaction of QF-OH and 4-dinitrofluorobenzene.In the structure of QF-OH-H₂S,the dinitrobenzene,as the recognition unit is located in the middle of the electron donor and the electron acceptor group,which will effectively block the ICT process within the molecule,wihci would lead to efficient fluorescence quenching.After treatment with hydrogen sulfide,the dinitrobenzene unit will be eliminated from QF-OH-H₂S and the ICT process would be recovered.Probe QF-OH-H₂S can selective react with H₂S and result in the strong green fluorescence.The fluorescence intensity of probe QF-OH-H₂S showed a good linear relationship with the concentration of H₂S,and the detection limit of H₂S was 36 n M.At the same time,the organic small molecule fluorescence probe has good biocompatibility and can be used for the detection of exogenous H₂S.