Synthesis And Application Of Fluorescence Probes Based On Salicylicaldehyde Hydrazine Derivatives

The development of fluorescent probes for detecting metal ions has attracted more and more attention because of their advantages of high selectivity and sensitivity without expensive instruments.Copper ion,is a kind of essential trace element,and also plays an important role in human life activities.So,it becomes very important for detecting its amount in aqueous environment and physiological conditions by employing the more sensitive and efficient fluorescent probes.This thesis focus on a series of compounds based on salicylicaldehyde hydrazine.Although their chelating metal recognition site has certain selective recognition ability for copper ions,their selectivity and sensitivity need to be improved.The aims of this work are to improve the recognition ability for copper ions by adjusting the electronic microenvironment of chelating sites and contacting distribution between fluorescent probe and ions.The specific strategies are as follows: on the one hand,the groups with electron-withdrawing or electron-donating ability are introduced on the side of salicylaldehyde derivatives,and the chelating ability to metal ions would be tuned by electronic effects.On the other hand,the different patterns of hydroxyl group are introduced to on the benzophenone side for increasing the hydrophilicity of the probe and changing electron microstructure along the conjugate direction of the probe,which would be benefit to improving their selectivity and anti-interference ability.(1)The cyano group(electron-accepting groups),triphenylamine and carbazole group(electron-donating groups)were introduced on the side of salicylicaldehyde derivatives,respectively,and the electronic structure of compound are tuned by electronic effect.The insert of cyano group makes the coordination ability of the chelating group decrease,and the proportion of ketone form fluorescent peak of CN-DBAS,so it also affects the sensitivity of the probe.On the contrary,the introduction of electron-donating groups could enhance the coordination ability,due to weak fluorescent intensity of the state of aggregation ketone form of TPA-DBAS and Cz-DBAS,it causese the sensitivity of the probe poorly.(2)The introduction of hydroxyl group with different pattern on the side of benzophenone derivatives not only increases the hydrophilic properties of the probes,but also improves the electron-donating effect,which could effectively change the electronic microenvironment for the metal identification site along the conjugate axis,thus improving its selectivity and sensitivity.After inserting one para hydroxyl or dihydroxy groups in para-positon,or dihydroxyl groups in meta-position of benzophenone side,these derivatives exhibited better hydrophilicity,and the porosity of the nanoparticles was improved in meta-mode.Herein,a series of compounds based on triphenylamine group(p-TPA-DPAS,pb-TPA-DPAS,mb-TPA-DPAS)showed excellent selectivity and lower detection limit for copper ion.In summary,we have realized the regulation of the detection selectivity and detection limit of the probe for copper ion by changing the structure of the terminal in benzophenone or salicylicaldehyde in these hydrazine-based probes,which provides good reference for the design of more efficient ion probe.