| The schiff base compounds are formed by the condensation of aldol amine.Salicylaldehyde schiff base are synthesized from salicylic aldehydes derivatives and amines,which is easy to synthesize and low cost.Compared with traditional luminescent materials,salicylaldehyde schiff base fluorescent probe can aviod the occurrence of the aggregation-caused quenching and can be applied in ion detection?biological sensing?pH?gas sensing and detection of explode.In dilute solvent,C-N and N-N bonds in the structure of molecular can rotate freely,and the non-radiation energy attenuates,consuming the energy of the excited state,and generating no fluorescence signal.In aggregation,hydroxyl groups formed intramolecular hydrogen bonds with nitrogen atoms,which prevented the intramolecular rotation?RIR?and the decay of non-radiative energy.This led to the enhancement of fluorescence in the form of radiation.Salisylaldehyde Schiff base compounds contain nitrogen atoms with unshared electrons and C=N double bonds,while metal ions provide vacant orbits,which are easier to form compounds.Therefore,when a certain amount of metal ions are added to Schiff base compounds,fluorescence signal changed can be observed,thus realizing the detection of metal ins.In this paper,a series of Schiff base compounds of salicylaldehyde were synthesized and characterized by salicylaldehyde,and a Schiff base sensor of salicylaldehyde was established to detect aluminum ions,pyrophosphate ions?PPi?,zinc ions and copper ions.The contens of the study are as follows:1.Synthesis of the probe 1 by salicylaldehyde and p-phenylenediamine under mild condition.synthetic probe 1was characterized by UV-visible absorption apectrum?UV-vis?of and fluorescence apectra?FL?,nuclear magnetic resonance hydrogen spectrum?1H NMR?,Fourier infrared spectrum?FT-IR?,Scanning electron microscope?SEM?etc,and through optimization of pH conditions,probe 1 was best in PBS buffer of 7.0 cndition best,at the same time under the condition of the selectivity and anti-interference are studied,such as implementation of aluminum ion and pyrophosphate detection of ions.Aluminum ion and the heteroatoms in the probe 1 for condensation,enhance the rigidity of the structure of molecular plane,resulting in chelating enhanced fluorescence effcet,the detection limit of aluminum ion of 3.9×10-7 M,and because of the strong force of aluminum ion and phosphate ion,when pyrophosphate was present,aluminum ions was detached from probe 1,making the fluorescence decreased,realizing the test of phosphate ion,the detection limit was 7.5×10-7 M.Finally,aluminum ions and pyrophosphate ions in sample were detected by standard recovery method,the recovery rate was 94%-101%,97%-101%,satisfactory results have been obtained.2.The probe 2 was prepared of 5-chloro-salicylaldehyde and hydrazine at room temperature in stir condition.Nitrogen atoms,hydroxyl and schiff base to form a relatively stable six ring structure and the ring was very stable.The rotation of the N-N single bond leads to the rotation of the ring structure,which,to some extent,consumes the energy of the excited state,resulting in a significant weakening of the fluorescence signal.When znic ion was added in the system of the probe 2,the heteroatom in the probe 2 are complesed with znic ion which the rotation of the N-N single bond in probe 2 was limited,so that the energy of the excited state back to excimer was carried out in the form of fluorescence,thus generating strong fluorescence signals.The detection limit was 5×10-8 M,which can realize the detection of zinc ion under physical condition and the recovery rate was 98%-101%.3.The probe 3 was prepared with 2-hydroxy-1-naphthalaldehyde,hydrazine hydrate and salicylaldehyde.The probe 3 has good aggregation induced emission performance.The fluorescence intensity of the probe 3 was very weak when in dilute,the fluorescence intensity of the probe 3 was higher in aggregation.When the water fraction was 80%,adding the copper ion in the solution the fluorescence intensity of the system was decreased,then adding the EDTA in the solution,the fluorescence intensity almost unchanged.At the same time,the selectivity of the probe 3 was studied.The detection limit was 2×10-8 M and the recovery rate was 98%-101%,indicating that the probe can better detect copper ion. |
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