Synthesis And Properties Of Oligothiophene-based Fluorescent Probes

Fluorescent probes have been widely used in many fields such as environment,biology,medicine,etc.because of their advantages such as high sensitivity,good selectivity and real-time detection.It is one of the research hotspots in recent years.This topic selected polythiophene as the main body,designed and synthesized three new types of organic small molecule fluorescent probes,and studied its synthetic route and sensing performance.1?A novel fluorescent“turn-on”probe 3TB for simultaneous sensing of Fe³⁺and Hg²⁺in aqueous mediabased on an oligothiophene Schiff base has been successfully synthesized and its fluorescent sensingproperties were investigated in details.3TB can selectively detect Fe³⁺and Hg²⁺by fluorescent spectroscopy among a series of various metal ions.Upon addition of Fe³⁺or Hg²⁺leads to a 44-fold or 19-fold fluorescence enhancement with a strong green fluorescence color.The binding stoichiometry ratio of3TB–Fe³⁺is recognized as 2:1 and 3TB–Hg²⁺as 1:1 proved by the method of fluorescence measurements,FT-IR and¹H NMR,and the possible binding mode of the sensing system is also proposed.The probe 3TB toward Fe³⁺and Hg²⁺was found to possess the excellent advantages of high association constants(1.34×10⁶ and 8.99×10⁴ M^-1),low detection limits?13.6 and 61.7 nM?,high selectivity and sensitiv-ity,good anti-interference performance,instataneous response,wide pH response range?5.0¹0.0?,andoutstanding fluorescence capacity to detect Fe³⁺from water.These investigated results indicate that 3TB is an ideal sensor for Fe³⁺and Hg²⁺recognition.Moreover,the probe was successfully appliedto effectively detect Fe³⁺in real water samples.2?An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide probe 3T-2CN was reported.the probe 3T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN^-with an excellent selectivity and high sensitivity.The sensing mechanism based on the nucleophilic attack of CN^-on the vinyl C=C bond has been successfully confirmed by the optical measurements,¹H NMR titration,FT-IR spectra aswell as the DFT/TD-DFT calculations.Moreover,the detection limit was calculated to be 0.19?M,which ismuch lower than themaximumpermission concentration in drinking water?1.9?M?.Importantly,test strips?filter paper and TLC plates?containing 3T-2CNwere fabricated,which could act as a practical and efficient solid state optical probe for CN^-in field measurements.3?A simple and efficient oligothiophene-based colorimetric and ratiometric fluorescent probe 3TS for highly sensitive and fast detection of Hg²⁺in water,soil and seafood has been developed.The probe can selectively detect Hg²⁺via the Hg²⁺-promoted deprotection reaction of thioacetals,which caused a remarkable color change from colorless to yellow and a strong fluorescence enhancement with emission color varying from blue to yellow,enabling naked-eye detection of Hg²⁺.The probe shows high sensitivity with the detection limit down to 10.3 nM.Visual color changes of 3TS were observed on filter paper and TLC testing strips when they were impregnated on testing strips and immersed in Hg²⁺solution.Moreover,the probe 3TS has been successfully used to rapidly detect trace amounts of hazardous Hg²⁺ions in tap,distilled,river and lake water,cropland soil,fish,shrimp and kelp samples with acceptable results and good recoveries.