Design,Synthesis And Performance Of Reactive Fluorescence Probe For Detecting Cysteine And Metal Ion

Fluorescence analysis have been widely used in the detection of bioactive molecules and the monitoring of environmental pollutants due to the operate simplicity,rapid response and excellent sensitivity.The recognition mechanism of reactive fluorescent probes derive from the specific chemical reaction between probes and analytes,thus exhibiting higher sensitivity and anti-interference capability,as well as more distinctive fluorescence signal change.At present,the research on reactive fluorescent probes has mostly focused on the design of fluorophores and recognition groups to obtain single-response fluorescent probes with excellent performance for small molecules,but very few systematic studies have been conducted on the substituent effects of the probes.In addition,single response probes mostly identify a single detection target,which is still challenging to be used for simultaneous detection of correlated co-existing analytes.To address these limitations,in this thesis,a number of representative fluorophores were selected,various substituents were introduced and their effects on the fluorescence performance of the probes were investigated,and"dual-key-and-lock"probes were synthesized by molecular design for the sequential detection of biological thiols and metal ions to prepare recoverable and visualized hydrogel fluorescent sensors,the specific contents are as follows:（1）Based on the 2-（2-hydroxyphenyl）benzothiazole（HBT）skeleton,methoxy,nitro and bromine groups were introduced at the response site to explore the effect of substituent electronic effects on the fluorescence properties of the intermediates.The results show that when the HBT hydroxyl group is the electron donor（-OCH₃）,it can obviously enhance the fluorescence emission and lead to the red shift of the emission peak and form a large Stokes shift,which is helpful to improve the recognition effect of the probe.On this basis,methoxy substituted cysteine（Cys）fluorescent probe BT-1was synthesized.Using acrylate as the reaction site,the probe restored the ESIPT effect by Cys addition-cyclization-cleavage reaction,and the fluorescence was enhanced more than 100 times.There is a linear relationship between the concentration of Cys and the fluorescence intensity of 506 nm in the range of 10-100μM,and the detection limit is as low as 450 n M.Under the coexistence of 10 common amino acids,the probe showed excellent selective recognition ability to Cys.（2）The fluorescent master of 2-（2’-hydroxyphenyl）benzimidazole（HBI）was chemically modified by introducing acrylate as the Cys response site and alkyne group as the Hg²⁺response site to synthesize the"dual-key-and-lock"probe BM-1.The probe has a"off-on-off"response mode,which is turned on by the addition-cyclization-cleavage reaction of Cys,and turned off by the hydration reaction of alkynyl catalyzed by Hg²⁺,thus achieving the sequential detection of Cys and Hg²⁺.The experimental results show that the fluorescence of the probe in 10min is enhanced by 500 times after adding Cys,and the probe has good temperature adaptability.There is a good linear relationship between Cys concentration and 468 nm fluorescence intensity in the range of 25-50μM,and the detection limit is 270 n M.After the addition of Hg²⁺to the detection solution,the fluorescence of the probe decreased linearly until quenched in the range of Hg²⁺concentration of 55-90μM and 100-150μM,and the detection limit was 145 n M.The probe has excellent anti-interference,and it can still realize the"double lock"detection of Cys and Hg²⁺under the coexistence of 27 kinds of common interferers.（3）The Fe³⁺fluorescent probe RBNCH was designed and synthesized based on the spirolactam ring-opening reaction with rhodamine moiety as the backbone.In acetonitrile/water solvent system,the detection of Fe³⁺has excellent selectivity and sensitivity.The fluorescence intensity of 568 nm increased linearly when the concentration of Fe³⁺was 100-200μM,and the detection limit was as low as 27 n M.On this basis,using the acrylamide group in the probe,the hydrogel fluorescent probe with naked eye recognition ability and recyclable function was prepared by copolymerization,and the instrumental application of the probe was realized.