Spectroscopic Studies of a New Multi-Element Sensitive Fluorescent Probe Derived from 2-(2-pyridyl)benzimidazole: Selective Discrimination of Zn2+ from Its Congeners

Abstract

ABSTRACT 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 Zn2+ ion as the emission wavelength of L undergoes a red shift by 31 nm upon binding with Zn2+ in methanol. In the presence of Cd2+, Hg2+, and other common cations, the emission wavelength of L remains unchanged, and thus allows us to discriminate Zn2+ from its congeners. Both L and its Zn2+ 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 Zn2+ 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 Zn2+.