Synthesis And Applications Of New Fluorescent Probes Based On Quinazolin-4(3H)-one Derivatives

Fluorescence molecular probe technology is a detection method that expresses the change of molecular recognition information by the change of fluorescence signal.The method is better than other traditional detection technologies and is valued by researchers because of its specific selectivity,good sensitivity and simple operation.In this paper,we designed and synthesizedaseriesfluorescentprobesbasedon2-hydroxy-5-methyl-3-?quinazolin-4-?3H?-keto?benzaldehyde that exhibits excited state intramolecular proton transfer?ESIPT?property,and explored their recognition effect.The results are as follows:1.Two fluorescent probes HEMQ and AHBM containing quinazolinone skeleton were designed and synthesized.In different buffer systems,the probe exhibits highly selective fluorescence and colorimetric dual response to ClO^-.In EtOH/PBS?1/1,v/v,pH=8.7?buffered solution,HEMQ exhibits highly selective fluorescence response to ClO^-with a complete fluorescence quenching at 594 nm,the color changed from yellow to colorless.In THF/PBS?1/1,v/v,pH=8.7?buffered solution,AHBM exhibits a highly selective fluorescence response to ClO^-with a significant blue-shifted and enhanced emission,and the color also changed from yellow to colorless.The recognition mechanism that two probes were oxidized to their precursor compound was comfirmed by ¹H NMR and HRMS analysis.2.AfluorescentprobeofPHMQthatbasedon2-hydroxy-5-methyl-3-?quinazolin-4-?3H?-keto?benzaldehyde was designed and synthesized.The probe exhibits specific selectivity towards NO in THF/Tris?6/4,v/v,pH=7.4?buffered solution.Within the pH range of 7.2⁹,the fluorescence intensity was significantly enhanced at 501 nm.The probe has high sensitivity to NO with a detection limit of 5.82×10^-6 mol/L.3.Anear-infraredfluorescentprobeBHPBbasedon quinazoline-4?3H?-ketone was designed and synthesized.In THF/Tris?1/1,v/v,pH=7.2?buffered solution,the probe BHPB exhibits highly selective fluorescence response to acidic amino acids that Glutamate?Glu?and Aspartate?Asp?over other amino acids with a significant fluorescence enhancement at 650 nm.The response of probe BHPB to Glu and Asp is very fast,and the probe is applicable to detect Glu and Asp using test strip.In addition,the BHPB can be used as a pH probe because of its good sensitivity to pH.4.A Schiff-base fluorescent probe DPMQ containing quinazolinone structure was designed and synthesized.The detection behaviors of DPMQ to trace water were investigated and the results show that DPMQ can detect trace water with fluorescence enhancement and fast response in different organic solvents.The detection limit is as low as 0.05%.The detection mechanism that probe reacts with water to product precursor aldehyde was comfirmed by ¹H NMR analysis.The probe can be applied to detection of trace water in organic solvents.