Synthesis Of Novel ESIPT Compounds And Its Application In Analytical Chemistry

With the development of society,the environment has also been polluted very serious.Therefore,it is very important to develop a high sensitivity,high specificity and accurate sensing method for use in important life activities such as quantitative or qualitative detection,to maintain normal life activities.The details of this paper are as follows:A fluorescent probe S-DPM for cysteine(Cys)and homocysteine(Hcy)has been prepareped by linking a dihydropyrimidobenzimidazole compound(DPM)with a 2,4-dinitrobenzene sulfonyl fragment.Upon treatment with Cys/Hcy,the probe S-DPM was reduced and released the hydroxyl group in the product DPM,thereby enabling the excited-state intramolecular proton transfer(ESIPT)process to shift the emission signal to a longer wavelength(from 420 nm to 521 nm).When 50 μM Cys were added,the emission(Em:521 nm)of the probe changed dramatically from 230 to 2400.The detection limit was also measured to be 0.15 μM(S/N = 3).Furthermore,the fluorescence imaging experiments in living cell demonstrated that probe S-DPM can permeate through the cell membrane is favourable for intracellular Cys/Hcy imaging.An excited-state intramolecular proton transfer(ESIPT)compound-based highly sensitive fluorescence probe,DPM was developed for the determination of trace levels of A13.DPM contains an o-phenolhydroxyl,pyrimidine and imidazole fragment,which can undergo ESIPT process and chelate with Al3+ in a HEPES buffer-ethanol solution(3:7 = v/v).The green-yellow(λem = 535 nm)fluorescence of the tautomeric forms of DPM turns into deep blue(λew = 451 nm)with～165-fold enhancement in emission intensity,in the presence of parts per billion level Al3+.The fluorescence changes in peak position and intensity of DPM are remarkably specific for Al3+ in the presence of other metal ions,which meet the highly selective requirements for practical application.The experimental results of pH dependent studies show that the response behavior of DPM towards Al3+ is pH independent in a large range from 5.0 to 12.0.The proposed probe has been used to detect Al3+ in water samples with a luimit of detection 0.15 nM.Furthermore,DPM can permeate through the cell membrane and detects intracellular Al3+ ions under a fluorescence microscope.A benzothiazospiro naphthopyran-based fluorogenic probe,called BTSP,has been developed for the highly sensitive and selective detection of hypochlorous acid(HOCl).As a spirocyclic compound,BTSP produces weak fluorescence with a quantum yield of Φ＝0.02 in response to PET from the 3-ethyl benzothiazole group to naphthopyran.However,the oxidation products of BTSP reacting with HOCl can produce strong fluorescence,and the fluorescence intensity of the reaction between HOCl and BTSP shows a good linearity in the HOCl concentration ranging from 2 to 25 μM.The detection limit is 18.5 nM(S/N = 3).The fluorescent turn-on mechanism is proposed to proceed by ring opening of the spironaphthopyran form promoted by HOCl to give merocyanine form which is a conventional fluorophore.In addition,the molecular probe was further demonstrated for fl uorescence imaging of HOCl in living cells.