Effect of Competing Alkali Metal Cations on Neutral Host's Anion Binding Ability

Shukla, R. C.; Kida, Toshiyuki; Smith, Bradley D.

doi:10.1021/ol0063104

Cited by 121 publications

(84 citation statements)

References 23 publications

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“…[20] An advantage of an ion-pair receptor over a simple ion receptor is that the number of competing interactions in solution (i.e., the formation of cation-anion pairs) is reduced. [21] Recently, we reported that simple mesooctamethylcalix[4]pyrrole (1) has the ability to bind ion pairs in the solid state; [22,23] these complexes consisted of a cone conformation in which the pyrrolic NHs were hydrogen bonded to the anion on one face of the macrocycle and the resulting electron-rich cavity, formed on the opposite face, contained either a cesium, imidazolium or pyridinium cation. Solvent-extraction studies, involving the use of water and nitrobenzene, provided evidence for the formation of 1:1:1 cesium/calix[4]pyrrole/ halide ion-paired complexes in the organic phase (halide = chloride or bromide).…”

Section: Introductionmentioning

confidence: 99%

Cooperative Binding of Calix[4]pyrrole–Anion Complexes and Alkylammonium Cations in Halogenated Solvents

Gross

Schmidtchen

Antonius

et al. 2008

Chemistry A European J

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Calix[4]pyrrole–chloride interactions are affected not only by the choice of countercation in halogenated solvents, but show a specific dependence on the way in which these cations are bound within the electron rich, bowl‐like calix[4]pyrrole cavity formed upon chloride anion complexation. In dichloromethane, the affinities of simple meso‐octamethylcalix[4]pyrrole (1) for methyl‐, ethyl‐, and n‐butylammonium chlorides are on the order of 105, 104, and 102 M−1, respectively, as determined from isothermal titration calorimetry (ITC) analyses. These cation‐dependent anion affinity effects, while clearly evident, are less pronounced in other halogenated solvents, such as 1,2‐dichloroethane. Support for the proposed cation complexation selectivity is provided by solid state X‐ray crystallographic analyses.

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Section: Introductionmentioning

confidence: 99%

Cooperative Binding of Calix[4]pyrrole–Anion Complexes and Alkylammonium Cations in Halogenated Solvents

Gross

Schmidtchen

Antonius

et al. 2008

Chemistry A European J

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“…The capsules 1×2 are based on two halfspheres: cavitand 2, functionalized with four azinium substituents, and calix [4]arene 1, containing four sulfonate substituents. Four pyridinium-sulfonate interactions bring the two halfspheres together to form a capsule ( Figure 1).…”

Section: Synthesis and Confirmation Of The Capsule Structurementioning

confidence: 99%

The Underestimated Role of Counter Ions in Electrostatic Self‐Assembly:[1+1] Cavitand‐Calix[4]arene Capsules Based on Azinium–Sulfonate Interactions

Oshovsky¹,

Reinhoudt²,

Verboom³

2006

Eur J Org Chem

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The apparent Ka values of the formation of [1+1] cavitand‐calix[4]arene capsules, based on azinium–sulfonate electrostatic interactions, obtained by direct titration experiments are concentration dependent due to the influence of the interaction of the charged capsule components with their initial counterions. 1H NMR and UV dilution experiments, in which this ion‐pairing is excluded, gave Ka‐values larger than 2·106 M–1 in methanol and methanol/water (1:1) for the capsule formation. The capsule encapsulates small guests like methanol, ethanol, etc., as proven by ESI‐MS. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…This strategy relies first on the selective 1,3-disubstitution of a para-tert-butylcalix [4]arene with a suitable asymmetric precursor (i.e., 6-8), followed by hydrazine-mediated cleavage of the phthalimide protecting groups. The resulting bisamines 12-14 were cyclized with suitable bis(acid chloride)s in moderate to high yields to afford the macrobicycles [15][16][17][18][19]. Oxidation of these macrobicycles with thalliumA C H T U N G T R E N N U N G (III) trifluoroacetate [14] gave the new heteroditopic calix[4]diquinone receptors 1-5 in yields of 42-89 %.…”

Section: Introductionmentioning

confidence: 99%

“…[15] The affinity of the receptor for a single ion is defined by the processes K 1(cation) and K 3(anion) , Scheme 2. Synthesis of receptors 1-5.…”

Section: Introductionmentioning

confidence: 99%

Cooperative AND Ion‐Pair Recognition by Heteroditopic Calix[4]diquinone Receptors

Lankshear

Dudley

Chan

et al. 2008

Chemistry A European J

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A new family of heteroditopic calix[4]diquinone receptors capable of the cooperative recognition of ion-pair species through a contact binding mechanism has been developed. The receptors bind contact ion pairs cooperatively, with an unprecedented AND recognition phenomenon being observed to operate in certain cases, in which receptors display no affinity for either of the individual "free" cation or anion, but bind the cation and anion ion-pair strongly. X-ray crystallographic, solution-state, and computational methods rationalize the observed recognition behavior of the receptors. It is shown that the contact ion-pair interaction occurs through a pi-stacking-mediated folding of the receptors such that the anion and cation binding sites are arranged in close proximity, while in the solid state an unusual ion-mediated receptor dimerization is observed. Molecular dynamics simulations are further used to explain the observed trends in the association constants of different ion-pair species and the mechanism of interaction.

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Effect of Competing Alkali Metal Cations on Neutral Host's Anion Binding Ability

Cited by 121 publications

References 23 publications

Cooperative Binding of Calix[4]pyrrole–Anion Complexes and Alkylammonium Cations in Halogenated Solvents

Cooperative Binding of Calix[4]pyrrole–Anion Complexes and Alkylammonium Cations in Halogenated Solvents

The Underestimated Role of Counter Ions in Electrostatic Self‐Assembly:[1+1] Cavitand‐Calix[4]arene Capsules Based on Azinium–Sulfonate Interactions

Cooperative AND Ion‐Pair Recognition by Heteroditopic Calix[4]diquinone Receptors

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