Selective, Fast-Response, and Regenerable Metal-Organic Framework for Sampling Excess Fluoride Levels in Drinking...

Prolonged consumption of water contaminated with fluoride ions (F^-) at concentrations exceeding 1.5 ppm can lead to considerable health implications, particularly in children and developing embryos. With irreversible and potentially severe forms of fluoride (F^-) toxicity such as skeletal fluorosis being endemic in at least 25 countries, constructing affordable, remote-access, reliable water-sampling methods for F^- contamination is an important goal. In this work, we present a novel lanthanide-based luminescent metal-organic framework, named SION-105, with a boron (B) receptor site whose interactions with F^- in aqueous solutions are simultaneously electrostatic and specific in nature because of its carefully designed structural environment. This allows the material to be easily regenerated and used over 10 cycles, setting it apart from most existing molecular and polymeric F^- sensors. SION-105 has been combined with a portable prototype sampling device that was designed and built in-house to measure F^- concentrations in natural groundwater samples taken from three different countries, with the results showing excellent agreement with ion chromatography analysis.