Induced‐Fit Encapsulation by a 1,3,5‐Alternate Calix[6]arene

Ménand, Mickaël; Leroy, Axel; Marrot, Jérôme; Luhmer, Michel; Jabin, Ivan

doi:10.1002/anie.200901722

Cited by 30 publications

(25 citation statements)

References 29 publications

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“…The molecule crystallized with disordered toluene molecules (which could not be satisfactorily located) in the relatively rare 1,3,5‐ alternate conformation, in which pairs of geminal rings are pointing in opposite directions (one “up” and one “down”; Figure ). A similar conformation was previously reported for the crystal structure of 19 b hosting a CH 2 Cl 2 molecule in the calix cavity . Four methoxy groups are oriented “in” (toward the cavity) and the rest are oriented “out”.…”

Section: Resultssupporting

confidence: 78%

“…From the chemical shift difference between pairs of axial and equatorial protons at 193 K and their coalescence temperature (208 K), a barrier of 9.9 kcal mol −1 was calculated for the Ar−OMe rotation process . This barrier is substantially lower than that determined for the rotation of the OBoc groups of 19 a (18.4 kcal mol −1 ) . It is highly likely that the reason for the lower barrier is that the rotating OMe groups in 18 are significantly less bulky than the OBoc groups present in 19 a .…”

Section: Resultsmentioning

confidence: 56%

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Calixrotanes: Calixarenes Incorporating Spiro‐Linked Cyclopropyl Groups

Shalev

Biali

2019

Chemistry A European J

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Macrocyclic compounds (calix[4]‐ and calix[6]arene derivatives) with aryl rings interconnected by spirocyclopropyl groups have been synthesized and structurally characterized. The compounds were prepared by the reaction of dichlorocarbene with calixarenes possessing exocyclic double bonds at the bridges, followed by reductive perdechlorination of the spirocyclopropyl groups. In all systems, pairs of geminal rings connected to the quaternary spiro carbon atoms are oriented anti, and the methylene groups of the cyclopropyl rings are located in isoclinal positions. Calix[6]rotane adopts in the crystal and in solution a 1,3,5‐alternate conformation. The presence of the spirocyclopropyl groups increases the rigidity of the macrocyclic ring.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 56%

Calixrotanes: Calixarenes Incorporating Spiro‐Linked Cyclopropyl Groups

Shalev

Biali

2019

Chemistry A European J

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“…The Boc‐protected p‐tert ‐butylcalix[6]arene 2 was reported by Jabin and co‐workers 9. The compound adopts an 1,3‐alternate conformation (Figure 1) in 1,1,2,2‐[D 2 ]tetrachloroethane with a unique Boc group self‐included in the calix cavity as evidenced by its high‐field chemical shift in the 1 H NMR (–1.61 ppm).…”

Section: Resultsmentioning

confidence: 61%

Calix[6]arene Functionalized at Four Bridges: Conformation and Intramolecular Guest Exchange

et al. 2015

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Reaction of the tert‐butoxycarbonyl derivative of p‐tert‐butylcalix[6]arene (2) with excess NBS under irradiation yields a calixarene with four bromomethine bridges as the major product (3). On the basis of the number of signals in the NMR spectrum, to the product was assigned a 1,2,4,5‐substitution pattern. X‐ray crystallography indicates that the product possesses the rct2 configuration and crystallized as a mixture of two conformers. The major form in the crystal exists in a 1,2,3‐alternate conformation where a single tert‐butoxycarbonyl group is self‐included in the cavity and all bromines are located at equatorial positions. A rotational barrier of 18.4 kcal mol–1 was measured for the intramolecular guest exchange rotational process that involves the mutual exchange between the unique self‐included Boc group and the Boc group on the opposite ring (Boc = tert‐butoxycarbonyl).

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“…Owing to the presence of distinct hydrophobic and hydrophilic regions and adjustable cavity dimensions in their molecular architecture, calixarenes have attracted considerable attention for the design of useful receptors [10][11][12][13][14][15][16][17][18]. By functionally modifying either the hydrophobic region (upper rim) or hydrophilic region (lower rim), it is possible to obtain efficient host molecules for complexing cations [11,12,[19][20][21][22], anions [23][24][25] and neutral species [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of deep cavity imidazolylcalix[n]arenes for selective extraction of silver

Chawla

Santra

Pant

et al. 2011

J Incl Phenom Macrocycl Chem

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A series of diphenylimidazolyl calix[n]arenes (n = 4, 6, 8) obtained from readily available starting materials have been examined for selective extraction of monovalent (sodium, potassium, caesium and silver) and bivalent ions (barium and lead). It has been determined that the synthesized deep cavity imidazolyl calix[n]arenes can selectively recognize silver ions through interaction with the imidazolyl groups appended at their upper rim in contrast to their usually encountered complexation with the ester functionalities present at the lower rim. The silver extraction efficiency is limited in the absence of the calix[n]arene skeleton while it is radically influenced by the ring size of imidazolylcalix[n]arenes examined.

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Induced‐Fit Encapsulation by a 1,3,5‐Alternate Calix[6]arene

Cited by 30 publications

References 29 publications

Calixrotanes: Calixarenes Incorporating Spiro‐Linked Cyclopropyl Groups

Calixrotanes: Calixarenes Incorporating Spiro‐Linked Cyclopropyl Groups

Calix[6]arene Functionalized at Four Bridges: Conformation and Intramolecular Guest Exchange

Evaluation of deep cavity imidazolylcalix[n]arenes for selective extraction of silver

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