Tetrapyridyl functionalised tetraphenylethylene AIEgen highly selective chemosensor for zinc sulfate

Abstract

In this work, we have used tetraphenylethylene bearing four pyridine moieties to the core (coded as TPy-TPE) AIEgen and which gives selective sensing of zinc ions when only sulfate is counter ion. Importantly, selective zinc sulfate ion sensing can be easily seen by the naked eye under UV-light i.e. at 365 nm wavelength, it clearly shows upon addition of zinc sulfate ‘Turn-On’ fluorescence was observed. The selectivity was demonstrated when no changes were observed not to other divalent cations (some of them having sulfate counter ion) nor zinc bearing other counter ions. The sensing of zinc sulfate was evaluated by means of UV-Vis absorption, fluorescence spectroscopy and for practical application using test strips. The selectivity of TPy-TPE towards zinc sulfate is shown to be in the 2:1 ratio. The binding constant (Ka) between TPy-TPE and zinc sulfate is 1.43 × 10−4 M−1 with a very low detection limit found to be 1.59 nM. Thus, we believe that this easy to make TPy-TPE may have real practical applications in the future.

Keywords

• Tetrapyridyl-tetraphenylethylene
• Sensor
• Zinc sulfate
• Fluorescence
• Turn-on