Construction of reversible enol-to-keto-to-enol tautomerization covalent organic polymer for sensitive, selective and multi-channel detection of iron (III)

Abstract

As an important element in organism, the lack and excess of ferric ions (Fe³⁺) may lead to an extensive range of diseases presenting with distinct clinical manifestations. In our design, a multi-channel probe with reversible enol-to-keto-to-enol tautomerization for the specific recognition and high sensitivity detection of Fe³⁺ was prepared. This paper reported a novel Cop-NC probe, Tris (4-formylphenyl) amine bearing 1,4-cyclohexanedione groups, which provides binding site for Fe³⁺ and also contributes both fluorescent and electrochemical signals. The as-synthesized Cop-NC exhibit intense fluorescence under an excitation wavelength at 378 nm with a quantum yield of 26%. Results of spectroscopic measurement show that Fe³⁺ can significantly cause a "Switch-off" fluorescence intensity effect. Simultaneously, the addition of Fe³⁺ can cause a "Switch-on" effect in electrochemical channel. It has realized the detection of Fe³⁺ with concentration as low as 0.4 μM and 1.0 nM in the fluorescence channel and redox channel, respectively. The development of the joint probe with multi-channel signals provides a more convenient and rapid detection method for food, medical treatment, environmental monitoring and other fields.

Keywords: Enol-to-keto-to-enol tautomerization; Ferric ions; Multi-channel probe; Tris (4-formylphenyl) amine.