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

Abstract

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, remoteaccess, 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.

Improving MOF stability: approaches and applications

“…More recently, Ebrahim et al presented a luminescent lanthanide-based MOF, SION-105, which proved to be highly sensitive to uoride ions in aqueous solution due to the strong interaction between threecoordinate boron atoms of the linker and the F À ions. 191 This MOF, due to its good stability, showed excellent regenerability even aer ten cycles. Unlike these chemical sensors, a Cu(I) triazolate framework, MAF-2, was designed as a gaseous oxygen sensor based on its high moisture stability, fast uptake and sorption kinetics for oxygen and other optical properties.…”

Temperature-dependent interchromophoric interaction in a fluorescent pyrene-based metal–organic framework

“…MOFs are crystalline materials which often exhibit high porosity and structural tuneability,9 and can be synthesised in a wide range of topologies 10. They have found numerous applications, including methane storage,11 heterogeneous catalysis12 as well as temperature,13 pressure,14 and chemical sensing 13,15. Optical properties of MOFs, such as their UV/vis absorption, are known to be finely tuneable by external stimuli, e.g.…”

Energy Transfer in Metal–Organic Frameworks and Its Applications

“…The result indicates that modifying the pyridine unit in the ligand enhances the ligand's sensitization for Tb 3+ , as evidenced by the improved Tb 3+ ‐to‐Eu 3+ EnT efficiency. More recently, a water‐stable recyclable Ln‐MOF in which a three‐coordinated boron (B) atom in the ligand acts as the active site for F − ions was presented by Ebrahim et al [ 51 ] Unlike previous studies, their research shows that the T 1 state of the ligand undergoes negligible changes when F − is presented in the MOF structure, and the interaction between B in the ligand and F − offers NR decay pathways for the quenching of Eu 3+ emissions.…”