A POM/viologen-based supramolecular fluorescent probe for Ag+ detection and application of visible hydrogel based intelligent sensing system

Abstract

Silver (Ag+) as a typical heavy metal ion has significant impacts on human health, so monitoring Ag+ level is an important issue. In this work, a new POM (polyoxometalates)/viologen-based supramolecular compound, [(HMSBP)2(γ-Mo8O26)]·4H2O (1) has been synthesized by hydrothermal method (MSBP = 1-(4-Methanesulfonyl-benzyl)-[4,4']bipyridinyl-1-ium). This POM/viologen-based supramolecular compound exhibits the unique supramolecular structure, excellent optical stability and superior fluorescence intensity, which is expected to become a promising fluorescent sensor. The coordination reaction between SO, pyridine N atom and Ag+ in compound 1 makes the detection of Ag+ achieved and the limit of detection (LOD) is 0.0411 μM in the range of 0.1–3 μM. Moreover, this supramolecular fluorescent probe has successfully realized the quantitative monitoring of Ag+ concentration in environmental water samples and commercially available disinfectant spray. Viologen is regarded as a good external stimulus responsive material, while its discoloration behavior can be exploited as an intelligent sensor system. The platform based on hydrogel and smartphones realizes the visualization and real-time quantification of Ag+, which provides an effective way for the rapid and convenient determination of Ag+. This provides a feasible way to promote the qualitative/semi quantitative detection of visual fluorescence POM/viologen sensors.