Crown Ethers: Sensors for Ions and Molecular Scaffolds for Materials and Biological Models

Gokel, George W.; Leevy, W. Matthew; Weber, Michelle E.

doi:10.1002/chin.200432273

Cited by 76 publications

(167 citation statements)

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“…97 Over the years, crown ethers that are selective for a vast range of organic and inorganic cations have been devised. 98 However the supramolecular community has not investigated Hofmeister phenomena using these macrocycles. Indeed, there is much to learn here.…”

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confidence: 99%

Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry

et al. 2017

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Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry. AbstractOn planet Earth, water is everywhere: the majority of the surface is covered with it; it is a key component of all life; its vapor and droplets fill the lower atmosphere; even rocks contain it and undergo geomorphological changes because of it. A community of physical scientists largely drives studies of the chemistry of water and aqueous solutions, with expertise in biochemistry, spectroscopy, and computer modeling. More recently however, supramolecular chemistry -with its expertise in macrocyclic synthesis and measuring supramolecular interactions -have renewed their interest in water-mediated non-covalent interactions. These two groups offer complementary expertise that, if harnessed, offers to accelerate our understanding of aqueous supramolecular chemistry and water writ large. This review summarizes the state-of-the-art of the two fields, and highlights where there is latent chemical space for collaborative exploration by the two groups. 4Water is ubiquitous and essential to life on planet Earth. A full understanding of aqueous solutions is therefore of significance to a wide range of fields within the atmospheric, environmental, biological and geological sciences. Within the chemical sciences, a deeper appreciation of how non-covalent interactions and chemical transformations are influenced by water would benefit a variety of fields. However, as we highlight here, there are many open questions regarding the chemical and physical properties of aqueous solutions.The aqueous realm is frequently bifurcated into the Hofmeister and hydrophobic effects, phenomena that respectively deal with the properties of solutions of salts and relatively nonpolar molecules. However, it is becoming increasingly evident that these areas do in fact frequently overlap; two prime examples being the accumulation of large polarizable anions at the air-water interface, 1-5 and the favorable interactions of polarizable anions with non-polar surfaces. [6][7][8][9][10][11][12][13][14][15] Thus the hydrophobic and Hofmeister effects are but part of a greater continuum of aqueous supramolecular chemistry, with many important and outstanding questions regarding the influence of the different kinds of non-covalent interactions involved.Studies of water and aqueous solutions have mostly been driven by the physical sciences community, a broad range of scientists whose expertise in spectroscopy, computer modeling, and biochemistry (to name just three areas) has generally not involved macrocycles or host molecules in general. However, for some time now, supramolecular chemists -with their expertise in macrocyclic synthesis and measuring weak non-covalent interactions -have been travelling a parallel course of exploration. This Review, inspired by discussions between sixteen members of each community at a recent workshop, 16 is an attempt to summarize what we know about aqueous solutions, what we do not know about them, and where the two communit...

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confidence: 99%

Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry

et al. 2017

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“…Since the advent of supramolecular chemistry in the 1980s, considerable effort has been invested in developing molecules that possess defined, predictable recognition properties [5][6][7] . Special focus has been placed on macrocyclic molecules, which have been shown to possess remarkable recognition properties with respect to anions 8 , cations 9 and small neutral molecules 10 . However, owing to a size discrepancy between host and guest molecules that is typically one to two orders of magnitude, applications with larger targets, such as proteins 2,11,12 , are limited.…”

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A synthetic nanomaterial for virus recognition produced by surface imprinting

et al. 2013

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Major stumbling blocks in the production of fully synthetic materials designed to feature virus recognition properties are that the target is large and its self-assembled architecture is fragile. Here we describe a synthetic strategy to produce organic/inorganic nanoparticulate hybrids that recognize non-enveloped icosahedral viruses in water at concentrations down to the picomolar range. We demonstrate that these systems bind a virus that, in turn, acts as a template during the nanomaterial synthesis. These virus imprinted particles then display remarkable selectivity and affinity. The reported method, which is based on surface imprinting using silica nanoparticles that act as a carrier material and organosilanes serving as biomimetic building blocks, goes beyond simple shape imprinting. We demonstrate the formation of a chemical imprint, comparable to the formation of biosilica, due to the template effect of the virion surface on the synthesis of the recognition material.

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“…Most likely the reason is the electrondonating character of anions, which is expected to lead to repulsive interactions with aromatic clouds. Anioninteractions are energetically less favorable than their cation-counterparts because the anions have greater van der Waals radii than cations and the binding energies strongly depend upon distance [2][3][4][5][6].In the field of supramolecular chemistry, crown ethers (CE) belong to the most popular hosts since their inclusion complexes have found a vast number of practical applications [7]. The aromatic ring-containing crown ethers may have enhanced complexing properties due to the -stacking interactions.…”

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Anion-π interactions—interactions between benzo-crown ether metal cation complexes and counter ions

Frański

Gierczyk

Schroeder

2009

J. Am. Soc. Mass Spectrom.

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The loss of X · radical from [M ϩ Cu ϩ X] ϩ ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M ϭ crown ether molecule, X Ϫ ϭ counter ion, ClO 4 Ϫ , NO 3 Ϫ , Cl Ϫ ). The loss of X · has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X · occurs with lower efficiency for the [NO 2 -B15C5 ϩ Cu ϩ X] ϩ ions than for the [B15C5 ϩ Cu ϩ X] ϩ ions, where NO 2 -B15C5 ϭ 3-nitro-benzo-15-crown-5, B15C5 ϭ benzo-15-crown-5. A reasonable explanation is that Anion-interactions prevent the loss of X · from the [NO 2 -B15C5 ϩ Cu ϩ X] ϩ ions. The presence of the electron-withdrawing NO 2 group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing the aromatic ring enriched in electrons, namely [NH 2 -B15C5 ϩ Cu ϩ ClO 4 ] ϩ where NH 2 -B15C5 ϭ 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anionrepulsion the loss of X · radical proceeds more readily for [ϩ . Iron reduction has also been found to be affected by Anion-interactions. Namely, the loss of . Among others, the authors discussed in details arene-arene interactions, hydrogen bonding to aromatic systems, cationinteractions, and the influence of counter ions on the cation-interactions. The possibility that aromatic ring may also interact with the anion due to the Anioninteractions has not been mentioned, which indicates that the anion-interactions are not so common. Indeed, the chemistry of noncovalent Anion-interactions is much less developed than that of the other types of interactions. Most likely the reason is the electrondonating character of anions, which is expected to lead to repulsive interactions with aromatic clouds. Anioninteractions are energetically less favorable than their cation-counterparts because the anions have greater van der Waals radii than cations and the binding energies strongly depend upon distance [2][3][4][5][6].In the field of supramolecular chemistry, crown ethers (CE) belong to the most popular hosts since their inclusion complexes have found a vast number of practical applications [7]. The aromatic ring-containing crown ethers may have enhanced complexing properties due to the -stacking interactions. It has been found that cation-interactions are of crucial importance for formation of complexes between dibenzo-24-crown-8 and tetramethylammonium cation [8]. Donoracceptor -stacking interactions have been established to significantly enhance the formation of mixed-ligand sandwich complexes formed by crown ethers [9]. Crown ethers having aromatic sidearms exhibited cation-interactions between K ϩ and a benzene ring [10]. Here we asked if the complexes of benzo-crown ethers with metal cation interact with the anion through the anion-interactions and if this interaction can be observed by ESI-MS. Obviously, a benzo-crown ether should contain an aromatic ring poor in electrons, e.g., nitro-benzo-15-crown-5 (NO 2 -B15C5). To the best of...

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Crown Ethers: Sensors for Ions and Molecular Scaffolds for Materials and Biological Models

Abstract: For Abstract see ChemInform Abstract in Full Text.

Cited by 76 publications

References 1 publication

Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry

Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry

A synthetic nanomaterial for virus recognition produced by surface imprinting

Anion-π interactions—interactions between benzo-crown ether metal cation complexes and counter ions

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