Synthesis And Properties Of Small Molecule Fluorescent Probes Based On Oligothiophene

With the development of industry,human and society,environmental pollution is increasing,a large number of heavy metal ions and toxic anions are discharged into the atmosphere,soil and water body,causing disease,irreversible damage and even death to human body.Due to the advantages of simple recognition and good reactivity,fluorescence analysis has been widely used in the detection of heavy metal ions and toxic anions in recent years.The contents are as follows:A new simple oligothiophene-indenedione-based sensor 3TI has been synthesized for the highly reactive and selective detection of cyanide anion?CN^-?in 70%aqueous media.The sensor 3TI displays distinct colorimetric and fluorometric detection of CN^-due to the addition of CN^-to the electron-deficient indenedione-vinyl group of 3TI,which hampers intramolecular charge transfer?ICT?efficiencies.The recognition mechanism of 3TI for CN^-was confirmed by ¹H NMR titration,FTIR spectra,HRMS analysis,and TD-DFT calculations.The sensor 3TI for CN^-shows the outstanding advantages of high fluorescence brightness,fast response time?30 s?,low detection limit?31.3 n M?,minimal p H dependence in the physiologically relevant range,and excellent selectivity in presence of other competitive anions.Encouraged by these desirable sensing properties,the 3TI has been successfully used for determination of CN^-in food sample,silica based sensing kits and fluorescence imaging in living cells with satisfactory results.A new highly selective and sensitive dual-mode sensor 3TD based on the conjugate of oligothiophene and barbituric acid moiety was developed for colorimetric and turn-on fluorescent detection of CN^-.The sensor 3TD exhibited high specificity towards CN^-by interrupting its own ICT producing thereupon a large blue-shift in UV-Vis spectrum and remarkable“turn-on”fluorescence emission.The detection limit was 0.226?M.The fluorescent detection of CN^-was well demonstrated by filter paper strips and silica coated TLC plates.Moreover,the sensor was also used to detect CN^-in agro-products with satisfactory results.Most importantly,in terms of these advantages of colorimetric and turn-on fluorescent dual-mode,immediate response,excellent selectivity,high sensitivity,low cytotoxicity,and good biocompatibility,the sensor 3TD was successfully applied into CN^-imaging in living cells,demonstrating its excellent value in practical application.A novel dual-functional fluorescent“turn-on”sensor 3TP based on oligothiophene-phenylamine Schiff base has been synthesized for discrimination and anti-interference over other metal ions.Sensor 3TP displayed a very fast (0.177?M for Al³⁺and 0.172?M for Fe³⁺)and wide p H response range?4.0–12.0?.The titrations,FT-IR and ESI-MS spectra.Importantly,sensor 3TP was served as an efficient solid material for the highly sensitive and selective detection of Fe³⁺on TLC plates.Moreover,the sensor 3TP has been successfully used to detect trace Al³⁺and Fe³⁺in environment and food samples with satisfactory results and good recoveries, samples.A new oligothiophene functionalized Schiff base sensor 3TDC has been successfully designed and synthesized.Sensor 3TDC exhibited“naked-eye”colorimetric and selective“on-off”fluorescence response toward Cu²⁺with high selectivity and sensitivity within a wide p H range.The binding ratio of the sensor3TDC and Cu²⁺was determined to be 1:1 through fluorescence titration,Job's plot,1H NMR titration,FTIR and DFT studies.The detection limit is calculated to be as low as set by U.S.Environmental Protection Agency??20?M?and the World Health Organization??30?M?.The binding constant?K_a?of Cu²⁺to sensor 3TDC was found response within 30 s and high anti-interference performance.Moreover,sensor 3TDC could be used as an effective fluorescent sensor for detecting Cu²⁺ions in various real water and food samples with good accuracy and high precision.