Synthesis And Recognition Performance Of Benzothiazole-based Long-wavelength Emission Fluroescent Probes

2-?2?-Hydroxyphenyl?benzothiazole?HBT?is a dye with excellent fluorescence properties with excited state intramolecular proton transfer.However,most of its derivative emit are in the blue and green regions.View of this,three kinds of 2-?2?-hydroxyphenyl?benzothiazole-based long-wavelength emission fluorescent probes were designed and synthesized.The recognition performance and spectral characteristics of the probes toward Hg²⁺,H₂S and Cys were studied.The results obtained are as follows:1.A 2-?2?-hydroxy-5-methylphenyl?benzothiazole-based fluorescence probe HBTDA for Hg²⁺recognition utilizing‘‘ESIPT+AIE”strategy has been developed and characterized.In THF/H₂O?1:1,v/v,PBS 20 mM,p H=8.5?mixed solution,probe HBTDA displays rapid fluorescence responses to Hg²⁺ions with high selectivity and sensitivity through Hg²⁺-triggered releasing of a compound possessing‘‘ESIPT+AIE”characteristics.HBTDA has excellent selectivity and anti-interference,and the detection limit=15.9 nM.Cell imaging investigations indicate that probe HBTDA is applicable to detect Hg²⁺ions in living MCF-7 cells.2.A new near-infrared?NIR?fluorescence dye o-HBTPY was synthesized from5-methyl-3-?2?-benzothiazolyl?salicylaldehyde and 4-acetyl pyridine.It consists of o-HBTPY as the fluorophore,linked via a hydroxyl moiety to an acrylate group.The acrylate group acts as a functional recognition moiety.A o-HBTPY-based NIR fluorescence probe HBTPA has been developed and characterized.The recognition behavior of HBTPA toward bio-thiols were studied.The results show that HBTPA can selectively recognize HS^-in DMSO/H₂O?v/v,1/9,HEPES buffer,pH=8.6?system.The probe has a very large Stokes shift of 250 nm and can quickly and sensitively detect the presence of HS^-with a detection limit of 260 nM.3.A 5-methyl-3-?2?-benzothiazolyl?-p-hydroxybenzaldehyde and 1,4-dimethyl-pyridinium iodide-based long-wavelength emission fluorescence probe HBTMP has been synthesized and characterized.The hydroxyl moiety of the dye was linked to an acrylate group.The acrylate group acts as a functional recognition moiety.The acrylate group acts as a functional recognition moiety.The recognition of cysteine?Cys?by probe HBTMP was studied.The results showed that HBTMP can recognize Cys in water solution?Tris-HCl buffer,1%DMSO?and release soluble ESIPT reactive dye 4-2.The existence of pyridinium structure leads to good Cys/Hcy discrimination ability,good selectivity,strong anti-interference ability and high sensitivity.The calculated second-order kinetic constant is 3.58 M^-1S^-1 and the detection limit is 120 nM.In addition,the cytotoxicity test results showed that HBTMP is MCF-7 cell permeable and applicable for fluorescence imaging of exogenous and intrinsically generated intracellular Cys in the living cells.Fluorescence co-localization studies reveal that HBTMP is a mitochondria-targetable fluorescent probe.