Synthesis And Application Of Fluorescent Dyes For Microenvironmental Detection Based On ICT Mechanism

Fluorescent dye is a molecule that can produce high fluorescence when reacting with the analyte.As a small organic light-emitting molecule,the fluorescent probe has the advantages of high sensitivity,good selectivity,convenient use and low cost.Fluorescent probes are widely used in biomedicine,liquid crystal display,thermosensitive pressure sensitive recording,optical disc recording,photochemical catalysis,etc.The ICT mechanism refers to the intramolecular charge transfer of molecules with push-pull electron structure in the excited state,causing the separation of positive and negative charges in the molecule.When the external environment changes or the molecule and the guest combine,it will affect the electronic structure of the push-pull,enhance or weaken the charge transfer within the molecule,and change the fluorescence spectrum.This paper designed and synthesized several small-molecule fluorescent probes based on ICT mechanism.main tasks as follows:1,Design and synthesis of near-infrared polar fluorescent dye PO1.PO1 was based on coumarin.It has strong push-pull electronic structures.PO1 havs the advantages of large emission wavelength,excellent light stability,and strong anti-interference ability.The fluorescence intensity at the maximum emission wavelength of PO1 has a good linear relationship with the change of environmental polarity.2,Basing on coumarin,designed and synthesized another polar fluorescent dyes PO2,PO2 was an example of ratio type fluorescent dye.Comparing with PO1,it has great anti-interference ability.The ratio of PO2 in fluorescence intensity I₄₁₀/I₄₆₀ has a good linear relationship with the polarity parameter??.3,A fluorescence probe Mito-VC was designed and synthesized basing on naphthalimide that can be used to detect the mitochondrial viscosity.Mito-VC was found to be a near-infrared ratio type fluorescent probe.Fluorescence intensity ratio I₆₂₀/I₄₇₀ has a good linear relationship with viscosity.The increase in viscosity will increase the I₆₂₀/I₄₇₀ value,and the probe has good anti-interference ability and light stability.Mito-VC can successfully locate the cell mitochondria.4,An example of a reactive fluorescent probe NH1 basing on the ICT luminescence mechanism was designed and synthesized using naphthalimide as the electron donating group and 3-bromocinnamic acid as the electron withdrawing group.The probe can complete specific response to hydrazine.As the hydrazine content increases,the fluorescence intensity rises and has a good linear relationship with the hydrazine content.Linear correlation coefficient was 0.99,and the detection limit is 0.23?M.The probe responds quickly with a response time of 80 s.In addition,NH1 has good selectivity to hydrazine,strong anti-interference ability,and can adapt to a large pH range.Experiments show that the probe can successfully stain cells and detect hydrazine in cells.In this paper,four simple fluorescent probes of PO1,PO2,Mito-VC and NH1 were designed and synthesized by relatively simple synthetic steps.And the structure was characterized by nuclear magnetic resonance hydrogen spectroscopy,carbon spectroscopy(¹H NMR,¹³C NMR),high-resolution mass spectrometry?HRMS?,etc.Its optical properties were analyzed by its ultraviolet absorption and fluorescence emission spectra.Among them,PO1and PO2 can detect the polarity of the solvent,and the performance is good;Mito-VC can complete the mitochondrial viscosity test;NH1 can achieve the detection of hydrazine in the cell,which has good application prospect...