The Constructions Of Organic Small Molecule Fluorescent Probes For Phosgene And Their Applications

Fluorescent probes have attracted great attention because of the advantages of realtime,convenience and high sensitivity.Phosgene(COCl2)is an amphiphilic reagent with high chemical activity,and reacts rapidly with amino group or hydroxyl group.It is commonly used in the preparation of chemical products such as pharmaceuticals,polymer materials,and pesticides.At the same time,it is a choking agent,which causes significant casualties in war.Therefore,it is of importance to develop detection methods with rapid speed and high accuracy to protect human health and safety.This Master’s thesis focuses on the research about fluorescence chemistry of phosgene detection,and has achieved the following results:1)The probe NSD-P was designed and synthesized using nitrobenzoselenidazole as the fluorophore and piperazine as the reaction site.This probe has a rapid and distinct response to phosgene and shows fluorescence "on" when it contacts with phosgene.But it shows a similar response to other electrophilic reagents such as oxalyl chloride because it just contains single reactive site.2)Probe 2a was constructed based on 1,8-naphthalimide,which utilizes benzoyl hydrazide as the recognition site.This recognition site produces two nucleophilic sites after intramolecular isomerization and forms a five-membered oxadiazolone after reacting with phosgene.By regulating intramtolecular charge transfer,the emission properties were affected.Probe 2a has a rapid response to phosgene in solution(30 s),a low detection limit(LOD=1.7 nM),and the fluorescent color changes a lot.In addition,the sensing product was isolated and characterized by multiple methods to verify the sensing mechanism.3)Using 2a as the basis,the sensing performance was optimized by structural improvements.By introducing different substituents in the para-position of the reaction site,probes 2b(R=CH3)and 2c(R=CN)at para-substituent of reactive site were synthesized and the effects of para-substituents on the sensing performance were explored.After spectral tests,probe 2c has better performance than 2a and 2b,with a response time of only 5 seconds,a low limit of detection of 1.4 nM,emission growth over 300-folds and good selectivity.Subsequently,probe 2c was embedded in test paper for the detection of gaseous phosgene.The results showed that the test paper could detect phosgene below the safe concentration of human body(～20 ppm).These results suggest that 2c is promising to apply in the field-detection of phosgene.