Study On Synthesis And Sensing Properties Of Phenothiazine And Derivatives

Phenothiazine is a heterocyclic compound,which has electron-rich nitrogen and sulfur heteroatoms,good hole-transporting ability and low ionization energy.As luminescent material,the non-planar "butterfly" structure of phenothiazine could hinder the intermolecular ?-? stacking and non-radiative transition to some extent.From the perspective of its molecular structure,sulfur atoms can be oxidized to sulfoxide(S = O)or sulfone(O = S = O).And due to its non-planar configuration,the 3,7,10 th positions are fully exposed and easily attacked by different substituents.Therefore,phenothiazines are widely used in optoelectronic materials,chemical sensors and biological probes.Based on the characteristics of phenothiazine derivatives with many reaction sites and strong electron-donating ability,high-efficient fluorescent probes could be developed for chemical sensing via the functionalization of different sites.In this dissertation,the fluorescence sensing and its mechanism were systematically presented,and the research progress of phenothiazine derivatives was summarized.With phenothiazine as the backbone structure,two kinds of fluorescent probes were designed and synthesized for the vapor detection of both nitrate explosives and organic amines pollutants.The main results are as follows:1.With N-methylphenothiazine as a starting material,a simple and efficient synthetic method of N,N-bis(2,4,6-tribromophenyl)methylamine(2N-BTBPMA)was developed,the mechanism was proposed and a fluorescent probe for nitrate vapor detection was designed and synthesized.By the optimization of the reaction conditions such as feeding ratio,solvent,reaction temperature and time,the synthetic method of 2N-BTBPMA was optimized,and the highest yield of 98% was realized.Through a detailed characterization of the intermediates,the reaction mechanism was proposed.Due to its multi-active site structure,it is suitable for constructing multifunctional organic functional materials.Therefore,a carbazole-based luminescent material 4Ph-C was synthesized,which showed excellent sensing performance to nitrate explosive vapor.In nitrate estersaturated IPN vapor,the fluorescence quenching rate reaches 90% in 25 s,and in saturated EGDN vapor,the quenching rate is 90% in 300 s.2.With phenothiazine as a raw material,a 4-fluorobenzophenone unit was introduced to its N site to afford a reversible fluorescent probe 4-phenothiazinyl-4-fluorobenzophenone(PTZ-BP-F)of organic amine vapor.With phenothiazine as the electron donor and 4-fluorobenzophenone as the acceptor,a fluorescent probe PTZ-BP-F was designed and synthesized,which has a typical intramolecular charge transfer(ICT)characteristics.The carbonyl functional group can react reversibly with amine,which will reduce its electron-withdrawing capacity,and the luminescence of ICT will be affected.The fluorescent probe PTZ-BPF showed fast response and excellent reversibility to organic amine vapor.Within 20 s of exposure to the organic amine vapor,the fluorescence quenching rate was 99%.After leaving the organic amine vapor,the fluorescence quickly recovered.Therefore,it can be used for reversible detection of environmental organic amines at a lower cost.In summary,based on phenothiazine derivatives,a synthetic method of 2NBTBPMA was invented.The modified method has the advantages of mild reaction conditions,metal catalyst-free,simple separation and high yield.A fluorescent probe 4Ph-C with good response to nitrate explosives was synthesized by functional group modification.On the other hand,a fluorescent probe based on ICT luminescence was designed and synthesized.The probe responds quickly to organic amine vapors and can be reused for many times.The fluorescent probe PTZ-BP-F showed excellent application prospects.