Highly sensitive and fast responsive 'turn-on' fluorescent sensor for selectively sensing Fe~(3+) and Hg~(2+) in aqueous media based on an oligothiophene derivative and its application in real water samples

摘要

A novel fluorescent "turn-on" sensor 3TB for simultaneous sensing of Fe~(3+) and Hg~(2+) in aqueous media based on an oligothiophene Schiff base has been successfully synthesized and its fluorescent sensing properties were investigated in details. 3TB can selectively detect Fe~(3+) and Hg~(2+) by fluorescent spec troscopy among a series of various metal ions. Upon addition of Fe~(3+) or Hg~(2+) leads to a 44-fold or 19-fold fluorescence enhancement with a strong green fluorescence color. The binding stoichiometry ratio of 3TB-Fe~(3+) is recognized as 2:1 and 3TB-Hg~(2+) as 1:1 proved by the method of fluorescence measurements, FT-IR and ~1H NMR, and the possible binding mode of the sensing system is also proposed. The sensor 3TB toward Fe~(3+) and Hg~(2+) was found to possess the excellent advantages of high association constants (1.34 x 10~6 and 8.99 x 10~4M~1), low detection limits (13.6 and 61.7nM), high selectivity and sensitiv ity, good anti-interference performance, instataneous response, wide pH response range (5.0-10.0), and outstanding fluorescence capacity to detect Fe~(3+) from water. These investigated results indicate that 3TB is an ideal sensor for Fe~(3+) and Hg~(2+) recognition. Moreover, the proposed sensor was successfully applied to effectively detect Fe~(3+) in real water samples.