The Design,Synthesis And Properties Study Of The Two Reactive Fluorescent Sensor Based On Fluorescein And DCDHF Fluorophore

Fluorescent sensor as an analytical tool is based on the molecular identification principle.The receptor binds the analyte selectively which induces the changes of the fluorescent properties.Utilizing the changes of fluorescence can realize the purpose of detecting analyte.Fluorescent sensors have been widely used because of its advantages,including high sensitivity,high specificity,low detection limits and good biocompatible.It can be used in-situ,real-time and on-line monitoring the analyte.The fluorescent sensor also has a high temporal and spatial resolution which can be used flexible.Hydrogen sulfide(H2S)is a well-known poisonous gas by its iconic smell of rotten eggs.In recent years,H2S is considered as an important gaseous signal molecule following the nitric oxide and carbon monoxide.As a neuromodulator,H2S can regulate physiological processes of the brain.It also can relax vascular smooth muscle and regulate cell proliferation and apoptosis.In cardiovascular disease field,hydrogen sulfide also shows potential therapeutic effect.Since hydrogen sulfide is an important gas in life science,the detection of hydrogen sulfide in cell is important for investigating its physiological activity.In this thesis,we have synthesized a fluorescent sensor Fluo-1 which is based on fluorescien fluorophore for detecting hydrogen sulfide with high specificity.The sensor Fluo-1 reacts with hydrogen sulfide and emilinate 2,4-dinitrophenyl by knoevenagel condensation.Then the fluorescein undergoes intramolecular charge transfer process and transforms from lactone-fluoresce in without fluorescent to quinone fluorescein with fluorescence.A new peak at 525nm is appeared after adding hydrogen sulfide to the solution of Fluo-1,and the peak strength become stronger and stronger with the content increase of the hydrogen sulfide.The colour of the Fluo-1 changed from colourless to yellow after adding hydrogen sulfide,which can be recognized by naked eyes.Fluo-1 can detect hydrogen sulfide with high selectivity and specificity.It also has good cell membrane permeability and low cytotoxitity.For these properties,Fluo-1 is hopeful for detecting hydrogen sulfide in cell.2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene)malononitrile(DCDHF)is a common chromophore which is widely used in designing nonlinear optical materials.The structure is featured by a conjugated ? linker with electron-rich between electron donor and electron acceptor.When increasing the capacity of electron donor in electron-donating or the capacity of electron acceptor in electron-withdrawing,the fluorescent spectrum and UV-Vis spectrum of the structure will shift to longer wavelength.On the contrary,the spectrum of the structure will shift to shorter wavelength.The DCDHF chromophore is sensitive to local environment such as solvatochromic,viscosity and pH.Utilizing these properties,we design and synthesis a class of pH sensitive fluorescent sensors based on DCDHF chromophor.They are specificaly responsive to different pH ranges with wavelength shift,changes of fluorescence intensity and solution colour.The series of fluorescent sensor can provide some references for detection of environmental changes under strong alkaline conditions.