Pendant arm pyrrolic amide cleft anion receptors

Navakhun, Korakot; Gale, Philip A.; Camiolo, Salvatore; Light, Mark E.; Hursthouse, Michael B.

doi:10.1039/b204295a

Cited by 27 publications

(4 citation statements)

References 11 publications

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“…It is difficult to ascribe specific values to the stability constants of receptor 17 , because of considerable discrepancies between the values obtained from different signals: the stability constants derived from amide groups joined by aliphatic linkers (triplet) are higher than those from internal aromatic CH protons, which are in turn higher than the values resulting from terminal amide protons (quartet; Table 3). A similar phenomenon was observed by Gale et al for another acyclic tetraamide and interpreted as reflecting the differences in the strength of interaction with the anion 61. However, discrepancies among the dissociation constants determined by following the shift of different protons indicate that the observed titration curves may not be the result of a simple 1:1 binding process 62.…”

Section: Synthesissupporting

confidence: 80%

Anion Binding versus Intramolecular Hydrogen Bonding in Neutral Macrocyclic Amides

Chmielewski

Jurczak

2006

Chemistry A European J

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Although amide groups are important hydrogen-bond donors in natural and synthetic anion receptors, studies on structure-affinity relationships of amide-based macrocyclic receptors are still very limited. Therefore, we synthesized a series of macrocyclic tetraamides 5-8 derived from 1,3-benzenedicarboxylic (isophthalic) acid and aliphatic alpha,omega-diamines of different lengths. (1)H NMR titrations in DMSO solution show that the anion affinity of these receptors decreases with increasing size of the macrocycle irrespective of the anion, and this suggests a minor role of geometric complementarity. Comparison with their previously studied pyridine congeners reveals that the isophthalic acid based macrocycles are less potent, in contrast to what was found for simple model diamides. Combined theoretical and experimental structural studies were carried out to determine the reasons behind this behaviour. The results show that the unexpectedly low anion binding ability of the isophthalic acid-based receptors is due to the self-complementary nature of the isophthalic bis-amide fragments: when two such moieties are present within a sufficiently flexible macrocycle, they adopt syn-anti conformations and bind each other by two strong intramolecular hydrogen bonds that close the macrocyclic cavity. Nevertheless, anion binding is able to break these hydrogen bonds and switch a macrocycle into a convergent all-syn conformation. Despite the ill-preorganized conformation, 20-membered receptor 6 is better than either its open-chain analogue (macrocyclic effect) and/or its isomer having differently placed carbonyl groups. The crystal structures of four anion complexes of the macrocyclic receptors are reported. X-ray studies and solution NMR data confirmed the inclusive nature of the complexes and pointed to strong involvement of aromatic CH hydrogen atoms in anion binding.

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Section: Synthesissupporting

confidence: 80%

Anion Binding versus Intramolecular Hydrogen Bonding in Neutral Macrocyclic Amides

Chmielewski

Jurczak

2006

Chemistry A European J

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“…Another strategy used to improve the anion affinity of receptors 1 is to introduce additional hydrogen bonding groups into a receptor. In one study, 23 a family of amide derivatives of ethylenediamine was obtained. Among the neutral receptors studied, the best results were obtained for tetramide 7 (Table 1).…”

Section: Pyrrolecarboxyamidesmentioning

confidence: 99%

Amide- and urea-functionalized pyrroles and benzopyrroles as synthetic, neutral anion receptors

2011

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This critical review is dedicated to the anion complexation chemistry of amide- and urea-functionalized (benzo)pyrroles, such as pyrroles, indoles, carbazoles, isoindoles, naphthalenodipyrroles and benzodipyrroles. It provides a comprehensive overview of these simple and neutral anion sensors from the first examples up to very recent studies. There is a discussion of a gradual progress made over time, often based on careful analysis of the properties of former generations that have subsequently led to obtaining excellent effectivities and selectivities. The influence of these species on other fields of chemistry and their applications there are also discussed (57 references).

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“…Compounds 7-9 were synthesised and their anion binding properties studied. 15 Notably, compound 7 showed a very high affinity for hydrogen sulfate anions (K . 10 4 M 21 ) presumably due to protonation of the amine functionalised receptor by the acidic anion and subsequent binding of SO 4 22 by the mono-positive host in DMSO-d 6 /0.5% water at 298 K (similar behaviour had been observed previously by Bowman-James and co-workers in mixed amine-amide macrocycles).…”

Section: 5-bisamidopyrrolesmentioning

confidence: 99%

Amidopyrroles: from anion receptors to membrane transport agents

Gale

2005

Chem. Commun.

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199

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Amidopyrroles have been employed in a variety of anion receptors and sensors. 2,5-Bisamidopyrroles show selective oxo-anion complexation properties in organic solution whilst bis-amides containing dipyrrolylmethane groups form strong complexes with dihydrogen phosphate anions in mixtures of DMSO-d6 and water. Deprotonation of the 2,5-bisamidopyrrole unit can lead to interesting solid-state structures including the formation of orthogonal hydrogen bonded dimers. Amidopyrrole groups have also been employed in receptors for ion-pairs and in membrane transport agents for HCl.

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Pendant arm pyrrolic amide cleft anion receptors

Cited by 27 publications

References 11 publications

Anion Binding versus Intramolecular Hydrogen Bonding in Neutral Macrocyclic Amides

Anion Binding versus Intramolecular Hydrogen Bonding in Neutral Macrocyclic Amides

Amide- and urea-functionalized pyrroles and benzopyrroles as synthetic, neutral anion receptors

Amidopyrroles: from anion receptors to membrane transport agents

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