Detection of Hg²⁺ with NBD‐based colorimetric chemosensor: Practical application to water samples and test strips

Abstract

A new nitrobenzoxadiazole (NBD)‐based chemosensor N′‐(7‐nitrobenzo[c][1,2,5]oxadiazol‐4‐yl)thiophene‐2‐carbohydrazide (NTCH) was synthesized for detecting Hg2+. NTCH could sense Hg2+ through a color change method from pale yellow to pink. Binding ratio of NTCH and Hg2+ was determined to be 1:1 with the analysis of electrospray ionization mass spectrometry and Job plot. Detection limit turned out to be 0.69 μM. In addition, NTCH could be successfully utilized for detecting Hg2+ in real water samples and visible color test strips. The probing mechanism of NTCH to Hg2+ was explained with 1H nuclear magnetic resonance (NMR) titration, Job plot, electrospray ionization mass spectrometry (ESI‐MS), and theoretical calculations.