Coumarin And Naphthalimide Based Fluorescent Probes And Their Paper Substrate Fluorescent Sensors

Fluorescent chemosensors is simple and easy to prepare,with high sensitivity and selectivity to anions,metal ions,and pH,which has attracted wide attention of researchers.Both coumarin and naphthalimide possess advantageous photophysical properties and structural tunability,and the fluorescent chemical sensors based on them demonstrate superior properties.Therefore,in this paper,a series of fluorescent chemosensors based on coumarin and naphthalimide were designed and synthesized by using various response mechanisms.The fluorescence responses of anions,metal ions,and pH were studied and successfully applied to water samples,food freshness monitoring,and in vivo fluorescence imaging.The specific contents include:(1)A reactive fluorescent chemosensor based on 7-(diethylamino)coumarin3-carbaldehyde was constructed for the detection of ClO-.The sensor exhibits high selectivity,sensitivity,and colorimetric recognition for ClO-.In the range of 0-20 μM,the fluorescence intensity ratio has a good linear relationship with ClO-,and the detection limit is as low as 92.6 nM.In addition,a paper-based fluorescence sensor was prepared on filter paper by soaking method,which can quantitatively detect ClO-in solution by combining with smartphone color recognition software.It has been successfully applied to the rapid quantitative detection of ClO-in eukaryotic cells and large-scale water sources.(2)A fluorescent chemosensor for the detection of Cu2+and S2-was constructed by reacting 7-(diethylamino)coumarin-3-carbaldehyde with isoniazid.The sensor can selectively recognize Cu2+ among many metal ions,and the fluorescence intensity has a good linear relationship with Cu2+(0～20 μM).The coordination structure and coordination ratio between CMIA and Cu2+were verified by Job ’s plot,theoretical calculation and single crystal diffraction analysis.The stable complex formed by the sensor and Cu2+ can detect S2-with high selectivity and sensitivity.A paper-based fluorescence sensor was prepared by loading the complex on the filter paper by immersion method.By combining the smartphone color recognition software,it has been successfully applied to monitor the freshness of raw meat.(3)A fluorescent chemosensor with aggregation-induced emission properties was designed and synthesized based on 1,8-naphthalimide for pH response.The sensor exhibits good AIE properties in aqueous solutions of DMSO,DMF,EtOH,CH3CN and THF.It has a good fluorescence response in a wide pH range.When the pH is in the range of 6～9.5,the fluorescence intensity and pH show a good linear relationship.In addition,the sensor is loaded onto the filter paper to realize the detection of pH in the solution.