Dual binding mode of alkylammonium cations to (1,3)-calix[5]crown-6 triesters

Gattuso, Mario; Notti, Anna; Pappalardo, Sebastiano; Parisi, Melchiorre F.

doi:10.1016/s0040-4039(98)00107-5

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…(b) Triesters. The remarkable site selectivity displayed by triethers 3b − f for linear alkylammonium ions is somehow lost in the case of triesters 3g − j , which show a dual binding mode with n BuNH 3 + ions . When exposed to 1 equiv of n BuNH 3 + under standard titration conditions (5 × 10 -3 M; CDCl 3 /CD 3 OD, 9:1, v/v; 293 K), compounds 3g − j form endo -cavity complexes in the 50−55% range (Table ), but display a second and competitive binding mode which takes place at the hydrophilic crown ether pocket of the lower rim.…”

Section: Resultsmentioning

confidence: 99%

“…Finally, the intensities of the peaks due to the complexed host correlate with those of the four resonances at very high field (δ −0.4 to −2.0 ppm) which are diagnostic of the cavity-included n BuNH 3 + guest. Although both binding sites (crown ether moiety and calix[5]arene cavity) actively recognize the n BuNH 3 + ion, endo -complexation is favored, and its percentage increases with increasing amounts of salt, until it levels off to about 80%, after 15 equiv of salt have been added. , …”

Section: Resultsmentioning

confidence: 99%

“…Cone conformer 3j : yield 62%, R f = 0.38 (cyclohexane/AcOEt 3:1); mp 218−222 °C (EtOH); MS, 1 H and 13 C NMR data have previously been reported . Anal.…”

Section: Experimental Section46mentioning

confidence: 87%

“…Selective recognition of differently shaped ions can either be provided by increasing steric hindrance of the substituents attached at the upper rim and/or rely on two topologically different regions around the polyether chain, featuring one or two lower rim pendant groups. Preliminary studies along this route have shown that tri- O -substituted (1,3)-bridged p - tert -butylcalix[5]arene crown-6 ethers, bearing alkyl or arylalkyl and alkoxycarbonylmethyl functionalities at the lower rim, behave as mono- or ditopic receptors for isomeric alkylammonium ions. These receptors generally form endo -cavity (inside the calixarene cup) and/or exo -cavity (at the crown ether moiety) 1:1 complexes according to the shape of the guest.…”

Section: Introductionmentioning

confidence: 99%

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Shape Recognition of Alkylammonium Ions by 1,3-Bridged Calix[5]arene Crown-6 Ethers: Endo- vs Exo-Cavity Complexation

et al. 2002

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A series of tri-O-substituted 1,3-bridged calix[5]arene crown-6 ethers bearing alkyl, arylalkyl, alkoxyalkyl, and alkoxycarbonylmethyl residues at the lower rim and either (t)()Bu or H substituents at the upper rim have been synthesized. (1)H NMR studies have shown that p-tert-butylcalix[5]crowns, irrespective of the size and nature of their lower rim pendant groups, adopt preorganized conelike conformations, whereas p-H-calix[5]crowns with bulky substituents preferentially exist in solution as partial cone conformers (C(1) symmetry). Calix[5]crown derivatives behave as mono- or ditopic receptors for isomeric butylammonium ions, forming endo-cavity (inside the calixarene cup) and/or exo-cavity (at the crown ether moiety) 1:1 complexes according to the shape of the guest. These two binding modes can be clearly distinguished and monitored by (1)H NMR titration experiments.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Cone conformer 3j : yield 62%, R f = 0.38 (cyclohexane/AcOEt 3:1); mp 218−222 °C (EtOH); MS, 1 H and 13 C NMR data have previously been reported . Anal.…”

Section: Experimental Section46mentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shape Recognition of Alkylammonium Ions by 1,3-Bridged Calix[5]arene Crown-6 Ethers: Endo- vs Exo-Cavity Complexation

et al. 2002

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“…Thus, it is important to modify crown ethers with appropriate hydrophobic moieties to enhance their interaction with specific organic ammonium ions. When crown ethers were coupled with calixarenes, more specific interactions of these compounds with organic ammonium ions have been observed by transport and extraction experiments [2][3][4] and spectroscopic measurements, 2,5 since the additional lipophilic moiety provided selective interaction with the nonpolar parts of the organic ammonium ions. We are particularly interested in constructing specific organic ammonium ion-selective electrodes using such calixarene-crown ether conjugates.…”

Section: Introductionmentioning

confidence: 99%

Discrimination of Methylammonium from Organic Ammonium Ions Using Ion-Selective Electrodes Based on Calix[4]arene-crown-6 Conjugates

Katsu

Matsumoto

2001

ANAL. SCI.

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Crown ethers have been successfully used to construct ionselective electrodes for primary organic ammonium ions as well as alkali metal cations. 1 The cavity of regularly arranged oxygen atoms of crown ethers provides the site for interaction with not only alkali metal ions but also the NH3 + group of organic ammonium ions. These electrodes, however, responded to primary organic ammonium ions in the order of their lipophilicity, because crown ethers lack the ability to discriminate the hydrophobic part of organic ammonium ions. Thus, it is important to modify crown ethers with appropriate hydrophobic moieties to enhance their interaction with specific organic ammonium ions. When crown ethers were coupled with calixarenes, more specific interactions of these compounds with organic ammonium ions have been observed by transport and extraction experiments 2-4 and spectroscopic measurements, 2,5 since the additional lipophilic moiety provided selective interaction with the nonpolar parts of the organic ammonium ions. We are particularly interested in constructing specific organic ammonium ion-selective electrodes using such calixarene-crown ether conjugates. We used the calix[4]arenecrown-6 derivatives shown in Fig. 1. Our results indicated that calix[4]-bis-2,3-naphtho-crown-6 has excellent ability to discriminate between methylammonium and other organic ammonium ions, although there was a great deal of interference by inorganic cations, especially Cs + . Experimental ReagentsThe reagents were obtained from the following sources:arene-crown-6 and 1,3-dimethoxy-calix[4]arene-crown-6 were from Acros (Geel, Belgium); dibenzo-18-crown-6 was from Aldrich (Milwaukee, WI, USA); potassium tetrakis(p-chlorophenyl)borate (KTpClPB) was from Dojindo Laboratories (Kumamoto, Japan); bis(2-ethylhexyl) sebacate, tris(2-ethylhexyl) phosphate and o-nitrophenyl octyl ether were from Fluka (Buchs, Switzerland); dioctyl phthalate was from Tokyo Kasei (Tokyo, Japan); and poly(vinyl chloride) (PVC) (degree of polymerization, 1020) was from Nacalai Tesque (Kyoto, Japan). All other chemicals were of analytical reagent grade. Electrode systemThe methylammonium-selective electrode was constructed using PVC-based membranes as reported previously. 6,7 PVC membranes had the following composition: 1 mg of ionophore, 20 mol% of KTpClPB relative to the ionophore, 60 µl (55 mg) of bis(2-ethylhexyl) sebacate and 30 mg of PVC. In some instances, the sensor membrane without KTpClPB was prepared. The materials were dissolved in tetrahydrofuran (about 1 ml) and poured into a flat Petri dish (28 mm diameter). Then, the solvent was evaporated off at room temperature. The resulting membrane was excised and attached to a PVC tube (4 mm o.d., 3 mm i.d.) with tetrahydrofuran adhesive. PVC membranes containing other solvent mediators were similarly prepared using 1 mg of ionophore, 20 mol% of KTpClPB relative to the ionophore, 60 µl of solvent mediator and 30 mg of PVC. For comparison, a sensor membrane based on an ionexchanger alone, composed of 0.5 mg of KTpC...

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Counterion‐Dependent Proton‐Driven Self‐Assembly of Linear Supramolecular Oligomers Based on Amino‐Calix[5]arene Building Blocks

Pappalardo¹,

Villari²,

Slovak³

et al. 2007

Chemistry A European J

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Self-assembly of a calix[5]arene bearing a 12-aminododecyl pendant group on the lower rim into supramolecular oligomers through intermolecular iterative inclusion events is readily triggered by contact with acid solutions and is reversed to the amino monomer precursor by treatment with a base. 1H NMR data are consistent with the formation of head-to-tail assemblies derived from endo-cavity inclusion of the alkylammonium moiety. Diffusion NMR and light-scattering studies provide evidence for the presence of oligomers in solution and show that different counterions and concentrations result in different oligomer sizes, whereas ESI-MS and SEM investigations, respectively, indicate that self-assembly also takes place in the gas phase and in the solid state. The growth of these supramolecular oligomers is concentration-dependent; however, as a consequence of the saline nature of the monomer, it also shows a distinct counterion-dependence owing to ion-pairing/solvation effects.

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Dual binding mode of alkylammonium cations to (1,3)-calix[5]crown-6 triesters

Cited by 15 publications

References 8 publications

Shape Recognition of Alkylammonium Ions by 1,3-Bridged Calix[5]arene Crown-6 Ethers: Endo- vs Exo-Cavity Complexation

Shape Recognition of Alkylammonium Ions by 1,3-Bridged Calix[5]arene Crown-6 Ethers: Endo- vs Exo-Cavity Complexation

Discrimination of Methylammonium from Organic Ammonium Ions Using Ion-Selective Electrodes Based on Calix[4]arene-crown-6 Conjugates

Counterion‐Dependent Proton‐Driven Self‐Assembly of Linear Supramolecular Oligomers Based on Amino‐Calix[5]arene Building Blocks

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