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The formation of a supramolecular core–shell like assembly upon interaction of the receptor with potassium sulfate enables its selective extraction.

A bowl‐shaped nitrogen‐doped nanographene composed of a pyrrolo[3,2‐b]pyrrole core substituted with six arene rings circularly bonded with one another has been prepared via a concise synthetic strategy encompassing the multicomponent tetraarylpyrrolopyrrole (TAPP) synthesis, the Scholl reaction, and intramolecular direct arylation. This synthesis represents the first case of programmed sequential intramolecular direct arylation reactions utilizing the different reactivity of C–Br and C–Cl bonds. The target compound contains two central pentagons confined between two adjacent heptagons—the inverse Stone–Thrower–Wales topology. The presence of both five‐ and seven‐membered rings in the final structure is responsible for interesting properties such as a perpendicularly aligned dipole moment, absorption and fluorescence in the orange‐red region, weak emission originating from the charge‐transfer character of a low‐energy absorption band, and a high lying HOMO. In the solid state slipped convex‐to‐convex π–π stacking dominates.

The crystals of new ambient pressure, high temperature (HT) polymorphs of neat pyrrolidine hemi- and hexahydrates were obtained using the IR laser assisted in situ crystallization method. They were subsequently investigated by single crystal X-ray diffraction and Raman spectroscopy. The transition from HT form to the known low temperature (LT) polymorph of the amine was monitored by X-ray powder diffraction. Although the investigated amine is an analogue to tetrahydrofuran (THF) which forms a stable clathrate hydrate, both binary pyrrolidine hydrates are dissimilar to the THF hydrate. The hexahydrate of pyrrolidine represents a class of semiclathrates where “guest” molecules are incorporated in the water framework. While cooling it undergoes a phase transition to the fully ordered phase. At higher temperatures the structure contains disordered pyrrolidine and water molecules. The latter adopts the same type of disorder as typical for H-disordered ice polymorphs (e.g., I h, I c, ...) and most clathrate hydrates.

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The use of a squaramide-based ion pair receptor offers a solution to the very challenging problem of extraction and transport of extremely hydrated sulfate salt. Herein we demonstrate for the first time that a neutral receptor is able not only to selectively extract but also to transport sulfates in the form of an alkali metal salt across membranes and to do so in a cooperative manner while overcoming the Hofmeister bias. This was made possible by an enhancement in anion binding promoted by cation assistance and by diversifying the stoichiometry of receptor complexes with sulfates and other ions. The existence of a peculiar 4:1 complex of receptor 2 with sulfates in solution was confirmed by UV–vis and 1 H NMR titration experiments, DOSY and DLS measurements, and supported by solid-state X-ray measurements. By varying the separation technique and experimental conditions, it was possible to switch the depletion of the aqueous layer into extremely hydrophilic or less lipophilic salts, thus obtaining the desired selectivity.