Binding of Tetramethylammonium to Polyether Side-Chained Aromatic Hosts. Evaluation of the Binding Contribution from Ether Oxygen Donors

Bartoli, Sandra; Nicola, Gina Rosalinda De; Roelens, Stefano

doi:10.1021/jo034905h

Cited by 22 publications

(19 citation statements)

References 25 publications

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“…Neuere Untersuchungen dokumentieren, dass in solchen Komplexen neben den Kationen-p-Wechselwirkungen auch solche mit den Polyoxyethyleneinheiten einen -allerdings kleinen -Beitrag leisten. [293] Eine einfache Quantifizierung des Anion-Effekts wäre durch unterschiedliche Lipophilie der Salze gegeben. Abbildung S11 illustriert, dassmit Ausnahme von Sulfonaten -die Wirt-Gast-Affinitäten mit der zunehmenden Löslichkeit der Salze in Chloroform tatsächlich näherungsweise linear abnehmen.…”

Section: Kationen-p-komplexeunclassified

Bindungsmechanismen in supramolekularen Komplexen

Schneider

2009

Angewandte Chemie

185

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Kräfte‐Sammelsurium: Supramolekulare Komplexe, wie der gezeigte, beruhen meist auf einer Kombination unterschiedlichster Wechselwirkungen, wie Ionenpaarbildung, Wasserstoffbrücken und Stapelwechselwirkungen. Die nicht immer einfache Charakterisierung von Natur und Stärke der intermolekularen Kräfte liefert Beiträge zum Verständnis biomimetischer Systeme wie auch zum Design von synthetischen Rezeptoren, Wirkstoffen und intelligenten Materialien. Die supramolekulare Chemie hat in den letzten Jahren eine enorme Ausdehnung erfahren, sowohl mit Blick auf mögliche Anwendungen wie auch auf analoge biologische Systeme. Bildung und Funktion supramolekularer Komplexe werden durch eine Vielzahl von oft schwer zu differenzierenden nichtkovalenten Kräften bestimmt. Ziel dieses Aufsatzes ist es, die entscheidenden Wechselwirkungsmechanismen zusammenhängend darzustellen und das Gesamtgebiet auf diese Weise zu klassifizieren. Als Beispiele werden meist organische Wirt‐Gast‐Komplexe gewählt, unter Berücksichtigung auch von biologisch relevanten Fragestellungen. Das Verständnis und die Quantifizierung der intermolekularen Wechselwirkungen ist für die rationale Planung neuer supramolekularer Systeme, einschließlich intelligenter Materialien, ebenso von Bedeutung wie für die Entwicklung neuer Wirkstoffe.

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Section: Kationen-p-komplexeunclassified

Bindungsmechanismen in supramolekularen Komplexen

Schneider

2009

Angewandte Chemie

185

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“…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].…”

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confidence: 99%

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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“…On the other hand, the presence of benzene rings increases the stability of the complexes due to the cation-p interaction. 21,22 Therefore, as clearly seen from Fig. 1, in the complexes of (CH 3 ) 4 P þ the cation-p interaction effect slightly dominates over the flexibility effect as…”

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confidence: 81%

“…[DB18C6 þ (CH 3 ) 4 N] þ ion) is enhanced by the cation-p interaction (because the distance between the charge and the p cloud is rather large, this interaction could be also considered as ion-induced dipole interaction). 21,22 The goal of this paper is to compare the complexing ability of crown ethers towards the tetramethylammonium cation and the tetramethylphosphonium cation ((CH 3 ) 4 N þ and (CH 3 ) 4 P þ ) by ESI-MS.…”

mentioning

confidence: 99%