Development Of Benzopyrylium-based Fluorescent Probes And Their Applications In Analytical Chemistry

Flavylium dyes have long history,and a great number of native dyes belong to them.Researchers have obtained a plenty of novel fluorophores by replacing substitutes in the flavylium platform.Up to now,the chemical properties of flavylium dyes and fluorescent probes have been widely reported.In our research,two fluorescent probes are constructed on the basis of benzopyrylium platform which are able to conduct Baeyer-Villiger reaction.The prime contents are as follows:In chapter 1,the basic structures,chemical properties of flavylium dyes and the research progress of relevant probes have been briefly introduced.By poring over the reference,we have come up with ideas about our research.In chapter 2,a new ratiometric fluorescent probe based on a benzopyrylium platform for hydroxyl radicals?·OH?has been designed and synthesized.The free probe BCN exhibits strong fluorescence emission at 652 nm.The ratiometric sensing of probe BCN toward·OH is realized by the oxidation of the dicyanovinyl group of probe BCN to afford the corresponding epoxide,which can further reaction with·OH to give a coumarin derivative as the final product.The research shows that the emission intensity ratio?I492/I652?were linearly increased with the concentration of Fenton reagent?0.2-3.5?M?.The detection limit was determined to be 30.8nM.Probe BCN exhibits high selectivity toward·OH over other reactive oxygen species and reactive nitrogen species.Furthermore,probe BCN have been employed to monitor·OH in living cells with a ratiometric fluorescent imaging manner.In chapter 3,the probe BP based on a benzopyrylium platform was synthesized for the detection of Cu²⁺.The free BP is non-fluorescent.The oxygen atom of the carbonyl group of BP with more positive charge can undergo a Baeyer-Villiger reaction inducing by Cu²⁺in the presence of dissolved oxygen,giving the corresponding lactone 3.Meanwhile,the other route of the reaction is that the aerobic hydroxylation of?-C-H bond in oxonium of probe BP before Baeyer-Villiger reaction,which transforming probe BP into the corresponding lactone 5.Additionaly,lactone 3 and 5 undergo hydration and tautomerization to yield coumarin C1 and C2 as the final products,affording fluorescence emission at 492 nm.The study depictes that fluorescence intensity was linearly increased with the concentration of Cu²⁺?0-1?M?and the detection limit for Cu²⁺was determined to be as low as 16 nM.BP also displays excellent selectivity to Cu²⁺over other metal ions.Furthermore,BP has performed well in detecting Cu²⁺in tap water and Moat River.