| Intramolecular covalently assembled fluorescent probes are a class of assembled probes based on specific chemical reactions.The fundamental feature of the "covalent-assembly" principle is that the color-enabling push-pull conjugative backbone of a dye is split into two fragments in the probe.These two fragments are covalently assembled to restore the dye through a chemical cascade,which is triggered selectively by the analyte of interest.The outstanding feature of this kind of probe is that the probe itself has no background interference,and has the characteristics of high detection sensitivity and fast response,which attracts the attention of researchers in the field of fluorescent probes in recent years.Based on the purposes of developing innovative recognition mechanism and high sensitivity fluorescent probes,combining with the principle of intramolecular covalent assembly,in this paper,five probes were synthesized based on two different backbone molecules(phenanthridine and coumarin derivatives),and studied their spectral properties as well as their applications in real samples.Firstly,two probes PTH and PTS that designed by employing phenanthridine backbone molecule have been developed,which are for sensing ClO-and organophosphorus nerve agent mimic(DCP),respectively.(1)PTH is a fluorescent probe that recognizes ClO-based on TEMPO(2,2,6,6-tetramethylpiperidine oxynitride)oxidation.Under the action of TEMPO and ClO-,the probe assembles the push-pull electron conjugated strand in situ to generate a fluorescent signal and respond to ClO-specifically.In addition,the probe was successfully applied in detecting trace ClO-in real water samples.(2)By combining "intramolecular covalent assembly" and "Lossen rearrangement",a probe PTS that responsed to DCP was designed and synthesized.After reacting with DCP,the probe underwent Lossen rearrangement occurred and then assembled a strong fluorescent phenanthridine skeleton molecule.In addition to investigating the response of probes to DCP solution,the prepared probe strips have a good recognition effect on DCP vapor,which has certain reference value for real-time monitoring of organophosphorus nerve agents in atmospheric environment.Next,arounding coumarin skeleton molecule,three probes CM480,CMBPO and CMF were designed and synthesized for fluorescence detection of Pd2+,BPO and F-,respectively.(1)Probe CM480 was synthesized around the Tsuji-Trost reaction,and the fluorescence detection of Pd2+was achieved under the reduction of triphenylphosphine.The probe has a fast response to Pd2+ low detection limit,and is resistant to interference by various metal ions.At the same time,the probe has also obtained relatively accurate test results in industrial wastewater and spike test.(2)Probe CMBPO for detecting BPO was synthesized by selecting 2-meth)lenephenylboronic acid pinacol ester as the site,which can be specifically oxidized by BPO,resulting to construct a push-pull electron conjugated strand.CMBPO showed an excellent spectral property,especially the shortening of response time,which improved the detection performance of these type of probes.(3)Based on thiophosphonate bond cleavage mechanism,a probe CMF for detecting F-was synthesized.Owing to the nucleophilicity of F-,the "P-O" bond can be cut off,and performed the intramolecular covalent assembly.The probe exhibited high sensitivity to F-,a low detection limit,and can detect F-in low-content fluorine-containing samples(such as toothpaste),which showed the practical value in practical application. |
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