Synthesis and sensing applications of a new fluorescent derivative of cholesterol

Abstract

A fluorescent 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD) derivative of cholesterol (CTN) was designed and synthesized. The compound forms a 1 : 1 non-fluorescent complex with Hg²⁺ in a solvent mixture of water and ethanol. Based on this discovery, a detection method with a detection limit (DL) of ∼0.08 μM for Hg²⁺ was developed. The presence of other commonly found metal ions has little effect on the detection. Though Fe²⁺ and Cu²⁺ have some interference, it could be avoided by a simple oxidation or reduction procedure. Further studies revealed that the complex can be used for the turn-on detection of some organophosphorus pesticides (OPs), such as DDVP, glyphosate, chlorpyrifos, diazinon and phoxim, either in solution or film state. The DLs for the five OPs are 0.015, 0.018, 0.087, 0.098 and 0.113 μg mL⁻¹ in solution, respectively. In addition, the compound as developed is interesting and attractive because it can sense the heavy metal ion and the OPs in a fast and sensitive manner. It is therefore believed that the developed method possesses the potential to be used for rapid on-site detection of hazardous chemicals.