Cryptates XXIV: Structure and stability of mononuclear and binuclear cation inclusion complexes of cylindrical macrotricyclic ligands

Lehn, Jean‐Maríe; Simon, Jacques

doi:10.1002/hlca.19770600116

Cited by 56 publications

(49 citation statements)

References 23 publications

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“…The following values have been obtained (at 25"): K1 and K2 correspond to the formation equilibria of the mono and binuclear complexes. The magnitude of the stability constants as well as the selectivity sequence are very similar to those obtained previously for other ligands of this type [21]. It is reasonable to assume that in the present case too, the cations were complexed by the two macrocyclic subunits.…”

supporting

confidence: 88%

“…The stability constants were determined at 25" in methanovwater 95:5 (vlv) using cation selective electrodes as described previously [21]; the ionic strength and the pH were kept constant with an aqueous solution of NEtBr ( 0 . 1~) and NEGOH (0.01~).…”

Section: Synthesis Of the Macrocyclic Compoundsmentioning

confidence: 99%

“…The stabifity constants for the complexes of ligand 2 with alkali cations have been measured in methanoYwater 95: 5 (v/v) using cation selective electrodes as in previous studies [21]. The following values have been obtained (at 25"): K1 and K2 correspond to the formation equilibria of the mono and binuclear complexes.…”

mentioning

confidence: 99%

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Synthesis and properties of chiral macrotricyclic ligands. Complexation and transport of chiral molecular cations and anions

Lehn¹,

Simon²,

Moradpour³

1978

Helvetica Chimica Acta

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SummaryThe optically active macrotricyclic cryptands 1 and 2, containing the binaphthyl group as chiral unit, have been synthesized. These compounds contain lateral cavities which may serve as anchoring sites for polar groups of the substrates and a central, chiral cavity large enough for including more or less completely the bulk of a molecular ion. Their complexation properties towards molecular ions give evidence for the occurrence of two types of processes: a) direct complexation of primary ammonium cations, like phenylethyl ammonium chloride, occurs with either 1 or 2; b) cascade binding, involving first complexation of an alkali cation followed by pairing with a molecular anion, takes place with 2. Process b) may be considered as a metallo-receptor model system where binding of an anionic substrate is dependent on initial binding of a cation. In both cases a) and b) weak resolution of chiral racemic substrates has been observed by extraction and transport (through a bulk liquid membrane) experiments. This indicates that in the complex the bulk of the substrate should be located close to the chiral unit and therefore more or less in the central cavity. In the case of cryptand 2, the resolution achieved for the ( ?C )-mandelate anion is markedly affected by the nature of the complexed cation.Molecular recognition, i.e. the ability of a ligand or receptor molecule to select and bind a substrate among a collection of molecules, can be achieved with a ligand containing an intramolecular cavity 1) of suitable size and shape for complete inclusion of the substrate, 2) lined with binding sites of appropriate nature and arrangement for strong attractive interaction with the substrate. Recognition thus requires the careful design of a receptor molecule presenting intermolecular complementarity. In particular, it involves discerning the proper interactions which will lead to substrate binding and inclusion, and building them into the walls which delineate the cavity of a synthetic receptor molecule.

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supporting

confidence: 88%

Section: Synthesis Of the Macrocyclic Compoundsmentioning

confidence: 99%

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Synthesis and properties of chiral macrotricyclic ligands. Complexation and transport of chiral molecular cations and anions

Lehn¹,

Simon²,

Moradpour³

1978

Helvetica Chimica Acta

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“…Furthermore, macropolycyclic ligands [28] [29] have been extensively studied of the macrocyclic receptor. The chelating ring can be adjusted in order to elaborate catalysts or design selective owing to their suitability as frameworks for many receptor sites [30] [31] [32] [33] [34] [35] . Since the first reports on spherical recognizers of transition or heavy metals [14] [15] [16] [53] , or of anions [16] [54] .…”

mentioning

confidence: 99%

Synthesis of Macropolycyclic Ligands Based on Tetraazacycloalkanes

Brandès¹,

Denat²,

Lacour³

et al. 1998

Eur. J. Org. Chem.

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A versatile synthesis of spherical macrobicyclic and cylindrical macrotricyclic ligands is described using 1,4,8,11‐tetraazacyclotetradecane (cyclam), 1,4,7,10‐tetraazacyclododecane (cyclen), or dioxo macrocycles as precursors. Macrobicycles have been obtained by allowing cyclam, cyclen, or 5,12‐dioxocyclam (1,4,8,11‐tetraazacyclotetradecane‐5,12‐dione) to react with a bis‐electrophilic spacer under high dilution conditions. A surprising selectivity has been observed for 2,6‐dioxocyclen (1,4,7,10‐tetraazacyclododecane‐2,6‐dione), which yields only macrotricycles under the same reaction conditions. Molecular modelling studies have been carried out to investigate the selectivity of the reactions, and good agreement has been observed between the theoretical predictions and experimental data. 1D‐ and 2D‐NMR studies reveal a highly rigid structure in the case of macrobicycles. The macropolycyclic ligands show very different basicities, which demonstrates the influence of the cross‐linker on the coordination properties of the ligands.

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“…It was therefore thought that complexation of anions should also be feasible with metallic cations located in related cavities. [9,10] A macrobicyclic biscopper cryptate complex was thus synthesised which was shown by potentiometric studies to display the expected interactions between the bis-metallic centres and a chloride anion. Another related compound containing one copper atom only displayed a chloride anion interacting with the Cu centre and the ammonium yields of the neutral compound 3.…”

Section: Introductionmentioning

confidence: 99%

Molecular Recognition of Anions by a Novel Organocobalt Receptor: Oxyanion versus Halide Selectivity in Water

Robitzer

Sirlin

Kyritsakas³

et al. 2002

Eur. J. Inorg. Chem.

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The dissolution of [Co{2,6‐(Me2NCH2)2C6H3}(η5‐C5H5)(H2O)]PF6 (1a) in dry methanol or dry acetonitrile affords compounds 1b and 1c, respectively, in which the water ligand of 1a has been substituted by MeOH or by CH3CN. The crystal structure analysis of 1b established that a strong intramolecular interaction exists between the methanolic proton and the NMe2 group that was interacting with H2O in 1a. For 1c no interaction could be found between the Co‐bound acetonitrile ligand and this NMe2 as it has changed its position in order to be as far away from the cobalt atom as possible. Whereas no reaction takes place between 1a and an excess of sodium iodide in water or in methanol, in acetone I− easily substitutes the water ligand of 1a to afford high yields of the neutral compound 3. Here also 1H NMR spectroscopic data are in favour of a structure with no interaction between the NMe2 and the iodide ligand as in 1c. Protonation of the free NMe2 unit of 1a by adding increasing amounts of HPF6 in water leads to the synthesis of 4a. The pKa of 1a in D2O was found to be 6.1. Treating 1a with acidic buffered water solutions (pH = 5.5) leads to the in situ formation of 4a. From these solutions, association constants were determined for Cl−, Br−, I−, AcO−, H2PO4− and NO3−. Significant selectivity in water for AcO− and H2PO4− vs. halide anions has been established. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Cryptates XXIV: Structure and stability of mononuclear and binuclear cation inclusion complexes of cylindrical macrotricyclic ligands

Cited by 56 publications

References 23 publications

Synthesis and properties of chiral macrotricyclic ligands. Complexation and transport of chiral molecular cations and anions

Synthesis and properties of chiral macrotricyclic ligands. Complexation and transport of chiral molecular cations and anions

Synthesis of Macropolycyclic Ligands Based on Tetraazacycloalkanes

Molecular Recognition of Anions by a Novel Organocobalt Receptor: Oxyanion versus Halide Selectivity in Water

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