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The synthesis of a hemicryptophane cage combining a CTV unit with a C3 symmetrical moiety bearing three urea functions is reported. This host was found to bind anions with higher binding constants than other previously reported hemicryptophanes. Due to its heteroditopic character this cage proved to be an efficient ion‐pair receptor. The best cooperativity effect was observed for the tetramethylammonium bromide (TMABr) salt, which was confirmed and rationalized by DFT calculations. A tris‐urea unit was combined with CTV moiety, leading to a heteroditopic hemicryptophane capable of binding ion pairs efficiently and selectively. [ABSTRACT FROM AUTHOR]

Two strategies have been explored towards the heterogenization of a host–guest catalytic system where either cavitand host [3iPO] or quaternary ammonium catalysts are grafted on silica supports. The bis-propargyl substituted triphosphonate cavitand [3iPO] was clicked onto an azido functionalized ultra-large pore SBA-15 type silica (UL-SBA-15). Ammonium hybrid materials were produced by grafting a propyltrimethylammonium chloride silane precursor onto silicas of varying porosities and textural properties (UL-SBA-15, SBA-15 and SiO2). Extensive characterization of each material is presented (XRD, N2 sorption, TGA, solid state NMR, elemental analyses, FT-IR). The effect of heterogenization was investigated in the coupling of CO2 with styrene oxide and was compared to all-soluble cavitand/ammonium homogeneous analogs. [ABSTRACT FROM AUTHOR]

Experimental approaches to tetraphosphonate cavitands bearing fluorenyl-phosphonate bridges are reported. Different routes are described depending on the substitution on the cavitand structure. Tetra-, tri- and di-bridged phosphonate cavitands have been prepared as precursors of fluorescent hosts, for which the stereochemistry is highly dependent on the substitution at the wide rim of the resorcin[4]arene scaffold. The conformational change in 3iotetraphosphonate cavitands has been characterised by X-ray diffraction. These new molecular receptors have been used for the recognition of acetylcholine. [ABSTRACT FROM AUTHOR]

The use of tri- and tetraphosphonate cavitand hosts in conjunction with tetrabutylammonium halide catalysts led to improved activity in the coupling of 1,2-epoxyhexane and CO 2 . Catalytic efficiency of the supramolecular assembly strongly relies on both the structural features and binding properties of the cavitand host. Tetraphosphonate cavitand host (4 i PO 1 ) was shown to impact more markedly n- Bu 4 NCl reactivity than triphosphonate counterpart (3iPO 3 ) due to its greater binding strength toward the ammonium cation as evidenced by titration experiments. The participation of acidic functional groups within the cavitand structure to activity enhancement was also clearly demonstrated. The best result was obtained with n- Bu 4 NI/3iPO 2 supramolecular assembly affording hexene carbonate in quantitative yield after 18 h of reaction. The improved performance observed with the cavitand 3 i PO 2 relies on a double activation of both the nucleophile (halide) through efficient encapsulation of the ammonium cation and the substrate (epoxide) through hydrogen bonding. [ABSTRACT FROM AUTHOR]

Enantiopurehemicryptophanes designed from the cyclotriveratrylene(CTV) unit display remarkable properties in selective host–guestrecognition or as supramolecular catalysts. The unprecedented controlof the helical chirality of the CTV unit by remote stereogenic centersof a tren moiety is reported, providing an original access to thishighly promising class of host molecules. Although the chiral centersand the CTV unit are separated by more than 10 Å, one singlediastereomer is formed; the nature of the diastereoselective processis discussed and the procedure is exemplified using different enantiopuretren derivatives. This work also highlights the influence of the chiralityof the CTV unit on the whole cage structure. [ABSTRACT FROM AUTHOR]

Abstract: Triphosphonate cavitand, 3iPO, has been designed for the recognition of ammonium in solution. This Letter presents a study of the selective guest–host recognition between Acetylcholine and Choline ions, ACh+ and Ch+, and the host. We are able to observe that the ACh+ ion replaces the Ch+ ion in the 3iPO-Ch+ complexes with a concomitant exchange/substitution constant of 7×104 M−1. Conversely a replacement of the ACh+ ions by the Ch+ ions in the 3iPO-ACh+ complexes has been also observed with a concomitant exchange constant of 5.8×103 M−1. The structure of the 3iPO-ACh+ complex is determined by single crystal X-ray crystallography. [Copyright &y& Elsevier]