Controlled Halogen-Bond-Involving Assembly of Double-sigma-Hole-Donating Diaryliodonium Cations and Ditopic Arene Sulfonates

The supramolecular dimensionality of halogen bonded architectures formed in the solid state by diaryliodonium salts is greater when the anion is a disulfonate rather than a monosulfonate. Specifically, diaryliodonium cations conventionally function as double-sigma-hole halogen bond (XB) donors and form 0D-heterotetrameric motifs when paired with monosulfonate anions. Here it is reported that when 1,5- and 2,6-naphthalenedisulfonate anions are used as ditopic XB acceptors, their assemblies with diaryliodonium cations provide architectures of higher dimensionality. 1,5-Naphthalenedisulfonate leads to the occurrence of 1D chains, while the longer and less sterically encumbered 2,6-naphthalenedisulfonate produces either 1D chains or 2D layers. The two-center I center dot center dot center dot OSO supramolecular synthon is observed most frequently, and the three-center I center dot center dot center dot OSO linkage was identified in some assemblies based on 2,6-naphthalenedisulfonate

Benzothienoiodolium Cations Doubly Bonded to Anions via Halogen-Chalcogen and Halogen-Hydrogen Supramolecular Synthons

The simultaneous binding of a molecular entity through two interactions is a frequently pursued recognition mode due to the advantages it offers in securing molecular self-assembly. Here, we report how the planarity of the benzothienoiodolium (BTI) cation allows for preorganizing in the cation plane the hydrogen, halogen, and chalcogen bonds (HBs, XBs, and ChBs, respectively) formed by the phenyl hydrogen, iodolium iodine, and thienyl sulfur. Crystallographic analyses of some BTI salts show how this interaction coplanarity enables their coupling to point toward a single anion that is coordinated via the supramolecular and heteroditopic synthon XB/HB or XB/ChB, the latter observed here for the first time. These synthons adopt a Janus-like arrangement around iodine. Crystallographic information suggests that interactions of the synthons act synergistically, e.g., when resulting in the unusually short ChBs formed by the thienyl sulfur. Determination of the molecular electrostatic potential, Bader's quantum theory of "atoms-in-molecules" analysis, and natural bond orbital investigations give information on the nature and energetic aspects of the short contacts observed in crystals

Sulfonium Salts as Leaving Groups for Aromatic Labelling of Drug-like Small Molecules with Fluorine-18

Positron emission tomography (PET) is unique in that it allows quantification of biochemical processes in vivo, but difficulties with preparing suitably labelled radiotracers limit its scientific and diagnostic applications. Aromatic [(18)F]fluorination of drug-like small molecules is particularly challenging as their functional group compositions often impair the labelling efficiency. Herein, we report a new strategy for incorporation of (18)F into highly functionalized aromatic compounds using sulfonium salts as leaving groups. The method is compatible with pharmacologically relevant functional groups, including aliphatic amines and basic heterocycles. Activated substrates react with [(18)F]fluoride at room temperature, and with heating the reaction proceeds in the presence of hydrogen bond donors. Furthermore, the use of electron rich spectator ligands allows efficient and regioselective [(18)F]fluorination of non-activated aromatic moieties. The method provides a broadly applicable route for (18)F labelling of biologically active small molecules, and offers immediate practical benefits for drug discovery and imaging with PET