Construction And Properties Of Ultra-sensitive Ratiometic Fluorescent Probes Based On AIE And DTBET Mechanisms

The ratiometic fluorescent probes can eliminate the error and improve the sensitivity by the built-in correction of the two emission bands.The fluorescent changes can be clearly observed and the fluorescence intuitive detection can be realized in the process of detecting the target object using the ratiometric fluorescent probes.At present,the development of a novel ratiometric fluorescent probe with practical value is a major research hotspot.In this paper,two ratiometric fluorescent sensors consist of rhodamine-tetraphenylethylene derivatives based on the through bond energy transfer mechanism were designed for the detection of Hg²⁺and hypochlorite molecules respectively.The main points are as follows:In first chapter,we introduced the research background of fluorescent probe,the luminescence mechanism of fluorescent probe,the research progress of fluorescent probe based on the mechanism of through bond energy transfer,as well as the research content of this paper.In second chapter,a ratiometric fluorescent probe TR-Hg detecting Hg²⁺based on the through bond energy transfer mechanism was presented.The probe TR-Hg consists of tetraphenylethylene moiety?energy donor?and rhodamine B thiolactone moiety?energy acceptor?.Because the rhodamine containing closed-loop structure does not emit fluorescence,the probe TR-Hg only emit fluorescence of the tetraphenylethylene moiety.After the reaction with Hg²⁺,the rhodamine moiety opened ring and the through bond energy transfer process occurred leading to the fluorescence of the rhodamine moiety.Combined with the advantages of aggregation-induced emission effect and through bond energy transfer mechanism,the emission leakage of dark energy donor during energy transfer is eliminated,and the energy transfer efficiency is close to 100%.The data shows that the probe TR-Hg has great selectivity for Hg²⁺,low detection limit?43 p M?,short response time?less than 10 s?and wide p H response range.After reacting with Hg²⁺,the fluorescent intensity ratio was enhanced by more than 30000 times.Finally,the probe TR-Hg can be successfully applied to cell imaging in onion epidermal cells,indicating that the probe TR-Hg has potential biological applications.In third chapter,a ratiometric fluorescent probe TR-OCl detecting HOCl based on the through bond energy transfer mechanism was presented.The probe consists of tetraphenylethylene moiety?energy donor?and rhodamine B thiohydrazide moirty?energy acceptor?.Before the reaction with hypochloric acid,the probe TR-OCl only emits fluorescence of the tetraphenylethylene moiety.Aafter the reaction with hypochloric acid,the monothio-bishydrazide of the rhodamine moiety becomes 1,2,4-oxadiazole,the process of through bond energy transfer,and fluorescence of the rhodamine moiety emerge.Energy transfer efficiency is close to 100%.The data show that the fluorescent intensity ratio of probe TR-OCl detecting hypochloric acid is more than 7000 times and the detection limit is 1.29 n M.The probe has excellent selectivity and fast responsiveness toward hypochloric acid.Moreover,the probe TR-OCl was able to successfully perform exogenous hypochloric acid imaging in B16F10 and WI38 cells,as well as endogenous hypochlorite imaging in RAW 264.7macrophages,suggesting potential applications of probe TR-OCl in livesystem.