Pinched-cone conformers of calix 4 arenes

Conner, Mark D.; Janout, Václav; Regen, Steven L.

doi:10.1021/ja00025a041

Cited by 93 publications

(44 citation statements)

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“…The unusual IH NMR spectra of 1 [4]arene derivatives. In particular, the bridging methylenes (-CH2-) remained a simple AB quartet with a 6,, characteristic of the cone-conformation (22,23).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and assembly of self-complementary calix[4]arenes.

Shimizu

Rebek

1995

Proc. Natl. Acad. Sci. U.S.A.

283

138

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A calix [4]arene was designed to reversibly dimerize and form an egg-shaped enclosure. Adhesive interactions in the assembly were provided by four self-associating ureas, which form a cyclic array containing 16 hydrogen bonds. The synthesis was completed in four steps from theEvidence for dimerization of the calixarene tetraurea was provided by 'H NMR, mass spectrometry, and the observation of encapsulated molecules. The resulting cavity was of sufficient size to capture guests such as ethyl benzene andp-xylene.

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Section: Resultsmentioning

confidence: 99%

Synthesis and assembly of self-complementary calix[4]arenes.

Shimizu

Rebek

1995

Proc. Natl. Acad. Sci. U.S.A.

283

138

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“…An important feature which contributes to the valuable binding properties of functionalized calix [4]arenes in the cone conformation concerns the plasticity of the calixarene matrix. The flexibility of the cavity allows adoption of numerous geometries ranging from an almost C 4 -symmetrical structure [20] [21] to that of a so-called "pinched cone" [22] [23] . In most structures where the latter shape has been encountered, two of the opposite aryl rings of the calixarene matrix lie almost coparallel, with the other two being essentially perpendicular.…”

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confidence: 99%

Complexation Studies with a Calix[4]arene-Derived Phosphinite − Divergent Arrays of Cavities Linked by MCl2 Fragments (M = Pd, Pt)

Faidherbe¹,

Wieser²,

Matt³

et al. 1998

Eur. J. Inorg. Chem.

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A cone‐shaped calix[4]arene‐derived monophosphinite, 25,27‐di(ethoxycarbonylmethoxy)‐26‐hydroxy‐28‐(diphenylphosphinooxy)calix[4]arene (L1), has been prepared in two steps from calix[4]arene. Treatment of L1 with [AuCl(tetrahydrothiophene)] in tetrahydrofuran gave the phosphinite complex [AuClL1] (1). Reaction of [PdCl2(PhCN)2] with two equivalents of L1 gave selectively trans‐[PdCl2L12] (2). Complex 2 · 2 CH2Cl2 crystallizes in the triclinic space group P1¯. The molecule is centrosymmetric, leading to a divergent array of the two calixarene moieties. The palladium atom resides outside both cones. As a result of steric interactions, the meta and para carbon atoms of the PPh2‐bearing aryl ring are significantly pushed to the interior of the cavity. The related platinum complex trans‐[PtCl2L122] (3), was obtained similarly from [PtCl2(PhCN)2] and presents in the solid state a structure which is isomorphous to that of 2. The diphosphinite 25,27‐di(ethoxycarbonylmethoxy)‐26,28‐bis(diphenylphosphinoxy)calix[4]arene (cone) (L2) has also been prepared and reacts with [PtCl2(PhCN)2] to yield oligomeric material.

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“…1, exists as four conformers in solution as cone, partial cone, 1,2-alternate, and 1,3-alternate, which are defined by the orientation of the respective phenolic rings toward each other and the linking methylene bridges. The conformation of the coned shape can be fixed in solution [19], but the rigid skeleton is still flexible resulting in geometric changes [20,21].…”

Section: Introductionmentioning

confidence: 99%