Chalcone-Based Colorimetric Chemosensor for Detecting Ni2+

Abstract

The first chalcone-based colorimetric chemosensor DPP (sodium (E)-2,4-dichloro-6-(3-oxo-3-(pyridine-2-yl)prop-1-en-1-yl)phenolate) was synthesized for detecting Ni2+ in near-perfect water. The synthesis of DPP was validated by using 1H, 13C NMR and ESI-MS. DPP selectively sensed Ni2+ through the color variation from yellow to purple. Detection limit of DPP for Ni2+ was calculated to be 0.36 μM (3σ/slope), which is below the standard (1.2 μM) set by the United States Environmental Protection Agency (EPA).The binding ratio of DPP to Ni2+ was determined as a 1:1 by using a Job plot and ESI-mass. The association constant of DPP and Ni2+ was calculated as 1.06 × 104 M−1 by the non-linear fitting analysis. In real samples, the sensing application of DPP for Ni2+ was successfully performed. DPP-coated paper-supported strips could also be used for detecting Ni2+. The binding mechanism of DPP to Ni2+ was proposed by ESI-MS, Job plot, UV-vis, FT-IR spectroscopy, and DFT calculations.