Spectroscopic studies of a new multi-element sensitive fluorescent probe derived from 2-(2-pyridyl)benzimidazole: Selective discrimination of Zn ~(2+) from its congeners

摘要

A new multielement sensitive fluorescent probe, 1-(2-(phenylthio)ethyl)-2- (pyridin-2-yl)-~1H-benzo[d]imidazole (L), has been synthesized by the reaction between 2-(pyridyl) benzimidazole and 2-chloroethyl phenyl sulfide. Excitation and emission wavelength of L are at 330 and 371 nm, respectively. Among various transition and nontransition metal ions, it can selectively read Zn~(2+) ion as the emission wavelength of L undergoes a red shift by 31 nm upon binding with Zn~(2+) in methanol. In the presence of Cd~(2+), Hg ~(2+), and other common cations, the emission wavelength of L remains unchanged, and thus allows us to discriminate Zn~(2+) from its congeners. Both L and its Zn~(2+) complex are well characterized by different spectroscopic techniques like ~~1H-NMR, ESI-TOF (+) mass, FT-IR, and elemental analysis data. The binding constant value of the complexation reaction between L and Zn~(2+) is found as 724.6 M ~(-1) in methanol. Density functional theoretical (DFT) studies nicely demonstrate the red shift in the emission wavelength of L upon binding with Zn~(2+).