A Unique Fluoride Nanocontainer: Porous Molecular Capsules Can Accommodate an Unusually High Number of “Rather Labile” Fluoride Anions

Abstract

The present work refers to the challenging issue of fluoride anion recognition/binding in water by taking advantage of the unique possibilities offered by the porous molecular nanocontainers of the {Mo132} Keplerate type allowing the study of a variety of new phenomena. Reaction of the highly reactive carbonate-type capsule with aqueous HF results in the release of carbon dioxide and integration of an unprecedentedly large number of fluoride anions--partly as coordinated ligands at both the pentagonal units and the linkers, partly as a disordered water/fluoride assembly inside the cavity. The internal assembly and some of the fluoride ligands are easily released, which provides interesting options for future studies regarding coordination chemistry and catalysis under confined conditions.

X-ray and Neutron Scattering Study of the Formation of Core–Shell-Type Polyoxometalates

“…Gigantic polyoxometalates (POMs) are a group of well-defined molecular clusters composed of early transition metal ions and oxo ligands with sizes ranging from ca. 2 to 6 nm. − Following the seminal work of Müller, gigantic POMs of various sizes and topologies have been obtained, and their molecular structures and applications have been extensively explored. − In contrast to regular nanoparticles, these POM clusters exhibit well-defined molecular structures (including surface structures) and tunable surface properties, e.g., charge density and hydrophobicity/hydrophilicity. − , Therefore, besides their well-developed applications in catalysis and as magnetically/electronically active materials, the gigantic POMs have served as perfect physical models to understand some fundamental science problems, including the solution behavior of polyelectrolytes, interfacial science, and the nature of chirality. − Moreover, owing to their porous structures and numbers of hydrogen bond donor and acceptor groups on the surface, the clusters have also been widely used in host–guest chemistry and supramolecular science as major building blocks. − The design and synthesis of gigantic clusters with required shape, size, and surface/electronic properties is critical to extend the applications of the POMs, but the synthetic capability to do this has so far not been attained. Also, additional information will be needed to fully understand the molecular structures and formation mechanism of the gigantic POMs currently in the database.…”

Reversible Temperature Dependent Dimerization of Transition Metal Substituted Quasi Wells–Dawson Polyfluoroxometalates

“…Condensation and self‐assembly of fluoroxometalate species will form the so‐called polyfluoroxometalates, where some of the oxygen atoms will be substituted by fluoride atoms. Known compounds include polyfluoroxomolybdates, fluorine containing Keplerates, polyfluoroxovanadates, and Keggin metatungstate structures with internal fluorine atoms replacing oxygen atoms . In addition, a fluorinated polyoxoanion, [H 2 F 6 NaW 18 O 56 ] 7– , that has a Wells–Dawson shell (an elliptic compound consisting of 18 tungsten atoms) and a prismatic {NaF 6 } core has been prepared .…”

Amide‐Triazolium‐Appended Anthracenes for Turn‐On Fluorescence Sensing of Anions in Noncompetitive and Competitive Solvents

“…There has been growing interest in anion recognition because anions play ubiquitous roles in chemical and biochemical processes, and some are also of great environmental and medical concern . In particular, the binding of fluoride and phosphate ions represents an important part of this field, because fluoride ions show duplicitous clinical nature, and phosphates play important roles in biology in signaling, energy transduction, and information storage and expression . Therefore, many man‐made receptors incorporating different anion‐binding sites and signaling subunits have been developed to realize the sensitive and selective detection of these anions.…”