A nitrobenzodioxazole‐based water‐soluble chemosensor for colorimetric quantification of aqueous hypochlorite

Abstract

A nitrobenzoxadiazole (NBD)‐based colorimetric chemosensor CNA (N,N,N‐trimethyl‐2‐(2‐(7‐nitrobenzo[c][1,2,5]oxadiazol‐4‐yl)hydrazineyl)‐2‐oxoethan‐1‐aminium chloride) was synthesised. The sensor CNA can detect hypochlorite (ClO⁻) via colour variation of yellow to colourless. The detection limit for ClO⁻ by CNA was analysed to be 0.36 μM. Moreover, the naked‐eye test strip was successfully applied for ClO⁻ detection. The probing mechanism of CNA to ClO⁻ was proposed to be a hydrolytic cleavage reaction of CNA by ClO⁻ and was demonstrated by electrospray ionisation mass spectrometry (ESI‐MS), Fourier‐transform infrared (FTIR), proton nuclear magnetic resonance (¹H NMR) analysis and density functional theory (DFT) calculations.