The Design Of Naphthalimide Fluorescent Probes For Calcium And Magnesium Ion And Their Application

Ca²⁺and Mg²⁺are the alkaline-earth divalent cation,and are also intracellular abundant metal ions.Besides,they play important roles in many physiological processes.For example,changes in the intracellular Ca²⁺concentration are related to physiological responses in obesity,as well as immune responses and pathological responses in Alzheimer?s disease.Intracellular decrease in Mg²⁺concentration and abnormal metabolic processing of Mg²⁺has been implicated in the causes of gastrointestinal,renal losses,hypocalcaemia,neurological manifestations,and a number of chronic diseases.Therefore,it is crucial to develop efficient analytical methods for detecting and monitoring of Mg²⁺at the level of cells.And the fluorescent molecular probe is a kind of efficient,convenient and sensitive method,which has been widely accepted by researchers in recent years,especially,naphthalimide fluorescent probes have become a hotspot in chemical and biological fields.In this work,two novel Ca²⁺and Mg²⁺fluorescent probes based on naphthalimide fluorophore were designed and synthesized.The recognition responses between probes and Ca²⁺and Mg²⁺were investigated by UV-vis and fluorescence spectra.The experiments indicated that probes had good performance and achieve the recognition and response by the coordination reaction between the receptor unit and Ca²⁺and Mg²⁺.Detailed as follows:1.Choose 4-bromine-1,8-naphthalene as the starting material for its no fluorescence emission and easy to reaction,and synthesized 2-1 naphthalimide fluorophore with large conjugate structure and easy modification through the fabrication in the top,3 and 4 of4-bromine-1,8-naphthalene.Based on the modifation of the fluorophore,we mainly consider the structure of the receptor unit which have the recognition function of Ca²⁺and Mg²⁺and could react with the aldehyde group.A Ca²⁺fluorescent probe naphthalimide was synthesized.The optical properties exhibited that probe 1 have good sensitivity and selectivity,rapid response time,good linear realation,low detection limit,and probe 1 response to Ca²⁺with the coordination of 1:1.Probe 1 was also successfully applied to celluar fluorescence imaging.2.Compound 2-1 reacted with 2-hydrazinylbenzo[d]thiazole to generate O-hydroxyl Schiff base probe 2.The results showed that probe 2 had good resonse to Mg²⁺.When Mg²⁺was added,the fluorescence intensity of probe 2 was enhanced about 15 times.Besides,the response to Mg²⁺was based on the specific affinity to Mg²⁺of O and N atoms in probe 2.Probe 2 also could apply for fluorescence imaging.