Synthesis Of Reaction-based Diketopyrrolopyrrole Fluorescent Probes And Theirs Application In Cyanide Anion Detection

Cyanide is a highly toxic substance.Therefore,it is highly significant to design and synthetize fluorescent probes that can detect the toxic cyanide with high selectivity and sensitivity.The fluorescence of probes used for cyanide detection is in blue to yellow range,which with red-emitting are rare.Diketopyrrolopyrrole(DPP)and its derivatives represent a class of brilliant red dyes,which have been extensively applied in fluorescent probes.They exhibit large extinction coefficients,high fluorescence quantum yields and exceptional light and heat stability.However,little fluorescent probes based on DPP to detect cyanide have been reported,which with red emission are very rare.Fluorescent probe with red emission is one of the pursuit goals when it is designed and synthesized.Because red light possesses deep tissue penetration,minimal photo-damage and low background interference.In addition,the mechanisms of fluorescent probes detecting of CN~-are mainly hydrogen bond,complexation or chemical reaction.However,hydrogen bond or complexation is a kind of weak interaction.Generally,those kinds of fluorescent probes possess poor selectivity and sensitivity.However,reaction-based fluorescent probes possess high selectivity and sensitivity,because of the formation of irreversible chemical bonds.DPP1,D PP2,DPP3 were synthesized in this paper and theirs photophysical properties and application in the detection of CN~-were tested.DPP1 and D PP3 could be used to detect CN~-with good selectivity and sensitivity.DPP nuclear is electron-deficient group with strong electronic withdrawing ability.Besides,the cyano and ester base connecting with the double bonds on D PP1 and the cyano connecting with the double bonds on DPP3 are electron withdrawing groups.These electron withdrawing groups reduce the density of electron cloud on the double bonds and improve the activity of double bonds,which make sure D PP1 and DPP3 can react with CN~-through Micheal addition reaction.DPP1 was got from diketopyrrolopyrrole with aldehyde group and tert-butyl cyanoacetate.The emission peak of D PP1 was at 640 nm in THF.Addition of CN~-aqueous solution to DPP1 in THF resulted in a rapid color change from pink to light yellow together with a large blue shift from 530 nm to 487 nm and fluorescence intensity at 640 nm was quenched 94% accompanied by appearance of a weak new emission at 560 nm.The detection limit was determined to be 0.75 ?M,which was far lower than the WHO guideline of 1.9 ?M.DPP compounds have serious aggregation-caused quenching(ACQ)phenomenon.Since the aggregation induced emission(AIE)phenomena is discovered,many researchers have been working on changing the DPP compounds from ACQ type to AIE type compounds.However,DPP compounds reported with AIE phenomena are still very few.In the third chapter,tetraphenylethene(TPE)with AIE effect was introduced into DPP2 and DPP3 molecules in order to modify DPP2 and DPP3.DPP2 was got from Wittig reaction and DPP3 was got from Suzuki coupling reaction.DPP2 and DPP3 both had strong fluorescence in solution or in solid state.DPP2 and DPP3 had aggregation induced fluorescence enhancement phenomenon in chloroform/n-hexane system.D PP2 and DPP3 fluorescence intensity increased 1.4 times and 1.3 times respectively,when the content of solvent n-hexane poor solvent of DPP2 and DPP3 reached 90%.In THF,DPP2 and DPP3 showed emission peaks at 606 nm and 632 nm with fluorescence quantum yield 32% and 11%,respectively.However,the powder samples of DPP2 and DPP3 emitted at 650 nm and 615 nm with fluorescence quantum yield 13% and 7%,respectively.The absorption peak at 340 nm disappeared accompanied by appearance of new absorption peak at 312 nm and emission peak intensity at 640 nm was quenched by 95% when CN~-aqueous solution was added to DPP3 in THF.The detection limit was determined to be 0.3 ?M.