Synthesis And Detection Performance Of Fluorescent Probes For Al(Ⅲ)、Zn(Ⅱ)、HClO And Hg(Ⅱ)

In this paper,four fluorescence probes based on salicylaldehyde,naphthaldehyde and dicyanoisoflurone were designed and synthesized for the specific detection of Al³⁺,Zn²⁺,HCl O and Hg²⁺,respectively.1.A benzoic acid（4-dimethylamino-2-methylbenzyl）-hydrazine（probeⅠ）was synthesized by the Schiff base reaction of 4-（dimethylamino-2-hydroxybenzaldehyde）with benzoylhydrazine.The probe exhibited remarkable photochromism（from colorless to yellow）due to the obstruction of the ESIPT process and C=N isomerization,and this photochromism has good reversibility.The probe could complex with Al³⁺at a molar ratio of 2:1,showing remarkable fluorescence response（at 475 nm）and strong anti-interference ability.The detection limit of Al³⁺by this probe was 11.9 n M.The complexation constant（K）between probeⅠand Al³⁺was5.62×10⁴M^-1.The probe has been used for rapid detection（5 min）of Al³⁺in real water samples with a p H range of 4-9 and fluorescence imaging of Al³⁺in living cells.2.Thiene-2-carboxylic acid（2-hydroxy-naphthalene 1-methyl-hydrazine）（probeⅡ）was synthesized by Schiff base reaction between 2-hydroxy-1-naphthalene formaldehyde and thiophenyl hydrazine.The binding ratio and complex constant（K）between the probe and Al³⁺were 1:1 and of 2.93×10⁵M^-1,respectively.After the coordination of probeⅡwith Al³⁺,the PET process was inhibited due to the chelation of nitrogen atom of the C=N group with Al³⁺,resulting in the color change of probe solution from colorless to blue as well as fluorescence enhancement（at 482 nm）.The probe showed good anti-interference performance,short response time（6 min）,wide p H range（3-11）,and the detection limit as low as 7.56 n M.The probe has been successfully applied for the labeling recovery of Al³⁺in actual water samples.3.N’-{5-[2-（3-Dicyanomethylene-5,5-dimethyl-cyclohex-1-enyl）-vinyl]-2-hydro xy-benzylidene}-hydrazinecarboxylic acid methyl ester（probeⅢ）was synthesized based on the reaction of dicyanoisoflurone derivatives with carboxyhydrazine methyl ester.It could effectively detect Zn²⁺and hypochlorite by inhibiting photoinduced electron transfer（PET）and intramolecular charge transfer（ICT）.The fluorescence of the probe at 653 nm was enhanced rapidly（<20 s）after the addition of Zn²⁺in the p H5-10 range.The detection limit of the probe toward Zn²⁺was 15.3 n M.The probe could complex with Zn²⁺with a molar ratio of 1:1,and the complex constant（K）was 2.34×10⁴M^-1.In the range of p H 3-8,probeⅢshowed a good fluorescence response（705 nm）to hypochlorous acid.The detection limit was 1.39μM,and the response time was 4 min.The probe has been successfully applied in visual bioimaging of Zn²⁺and hypochlorous acid in Hep G2 cells,and realized the detection of Zn²⁺and HCl O in actual water samples.4.Pyridine-2-carboxylic acid{5-[2-（3-dicyanomethyl-5,5-dimethylcyclohexyl-1-alkenyl）-vinyl-2-hydroxy-benzyl}-hydrazine（probeⅣ）was synthesized based on dicyano-isoflurone derivatives and 2-pyridine-formyl hydrazine.After binding with Hg²⁺,the PET process was inhibited,allowing the fluorescence signal（at 660 nm）of the probe to be restored,and significant color change.The molar ratio of probeⅣto Hg²⁺was 1:1,and the complex constant（K）was 1.627×10⁴M^-1.ProbeⅣshowed good selectivity with Hg²⁺,strong anti-interference ability,large Stokes shift（220 nm）,short response time（<30 s）,wide p H range of 8-10,high sensitivity,and detection limit as low as 5.6 n M.The probe has been successfully applied to detect Hg²⁺in actual water samples.