Sunlight and UV driven synthesis of Ag nanoparticles for fluorometric and colorimetric dual-mode sensing of ClO.

A photo-responsive compound BINOL-LA (1) having a rigid backbone ending up with two 5-membered cyclic disulfide moieties was designed. BINOL-LA capped Ag nanoparticles (1@Ag NPs) with a network structure were synthesized in a green way by sunlight or UV lamp irradiation. 1@Ag NPs exhibit a selective recognition towards ClO- in aqueous solution with a switch-on fluorescence response and a visual color change, with detection limits of 0.17 µM and 1.54 µM, respectively. The sensing mechanism is based on the ClO--mediated oxidation of AgS bond, resulting in a disaggregation of 1@Ag NPs assembly. With the strategy demonstrated here, ClO- in tap water and lake water can be detected quantitatively in 5 s.