Design,Synthesis And Function Study Of Fluorescence Sensors Based On Naphthalimide Linking Piperazine

Because of theirs fast and specific fluorescence response to target ions and molecules,fluorescence sensors can realize non-destructive in-situ and real-time detection,and have attracted attention due to their advantages of low cost and good sensitivity.Naphthalimide is a kind of fluorescence platform with excellent performance.It has the characteristics of easy modification,high quantum yield and wide wavelength control.It is widely used in the development of fluorescence sensors.Based on the naphthalimide platform,a series of fluorescence sensors utilizing the electron conjugation between piperazine and fluorophore is designed and synthesized,and have the ability to complex with ions.The mercury ions,iron ions,and aluminum ions is detected and imaged separately.The specific work is as follows:In the first chapter,the background and development of fluorescent sensors are reviewed,and the optical properties of naphthalimide fluorescent platform are introduced.Based on the development of naphthalimide fluorescent sensors,the design strategy of this paper is brought up.In the second chapter,a fluorescence sensor Nap P-deap is constructed based on the mechanism of photoinduced electron transfer.The fluorescence sensor uses naphthalimide as the fluorophore,piperazine,pyridine,diethylamine propylthio as the recognition group.After complexing mercury ions in the solution,the fluorescence increased by a maximum of 11.6 times.The fluorescence intensity has an excellent linear relationship in the range of 0～1 Hg equiv,R²=0.997,and the detection limit is 2.2×10-8 M.At the same time,Nap P-deap can be successfully applied to fluorescence imaging of mercury ions in cells and tissues.Due to the presence of multiple recognition groups,which have different recognition modes in different solvents,the synthesis mechanism of the reference compound Nap B-deap was studied,and the design of the molecular optical switch was carried out based on its properties.Through the working curve and nuclear magnetic titration speculated that the sensor and mercury ion 1:1 complexation,complexation constant is Ka=1.46×10⁷M^-1.In the third chapter,based on the previous work,the sensor Nap TP was designed with piperazine and pyridine as the recognition groups.The fluorescence sensor can be encapsulated with CTAB emulsion and the iron ions can be detected in the pure water system.The detection of iron ions is achieved by the complexation of piperazine,pyridine and iron ions.The effect of the sensor and ferric ion enhanced the fluorescence by 8 times,and the quantum yield increased from 0.9%to 14.8%.The fluorescence intensity of the sensor has a good linear relationship R²=0.986 in the range of 0～8 iron ion equiv.The detection limit is8.05×10^-7M,which is lower than the requirements of the Environmental Protection Agency for water iron ion limits.Through the working curve and nuclear magnetic titration,it is deduced that the sensor and iron ion are 1:1 complex and the complexing constant is Ka=1.34×10⁶M^-1.In the fourth chapter,base on the second work,the sensor Nap PT was designed with piperazine and dithioacetal as the recognition groups.The sensor had a specific response to aluminum ions and the flurescence enhanced 72 times after compared with aluminum ions.When the sonser concentrastion was 1μM,the fluorescence intensity showed and excellent linear relationship R²=0.997 in the rang of 0-20 aluminum equiv.The detection limit is:5.26×10^-8M.