Synthesis of Cucurbituril-spermine-[2]rotaxanes of the Amide-type

Buschmann, Hans‐Jürgen; Wego, Andreas; Schollmeyer, Eckhard; Döpp, D.

doi:10.1080/10610270008049132

Cited by 25 publications

(32 citation statements)

References 27 publications

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“…Indeed, any CB[n] complex which extends past the rim of the cavity can be considered a pseudorotaxane starting material for reactions leading to the formation of rotaxane, polyrotaxane, and polypseudorotaxanes. [186] CB [6]-based rotaxanes have been prepared in solution by dipolar cycloadditions, [147,[150][151][152]187] stoppering with dinitrophenyl groups, [188] amide-bond formation, [189][190][191][192][193] ionic interactions, [194] and coordination of alkylcobaloximes. [195,196] A variety of polymer backbones and side chains have been threaded with CB [6] beads including polyacrylamides and polystyrenes, [197] poly(hexamethyleneimine), [151,198] di-and polyviologen, [98,199] and poly(propyleneimine) dendrimers.…”

Section: Pseudorotaxanes Rotaxanes and Their Oligomeric Analoguesmentioning

confidence: 99%

The Cucurbit[n]uril Family

et al. 2005

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In 1981, the macrocyclic methylene-bridged glycoluril hexamer (CB[6]) was dubbed "cucurbituril" by Mock and co-workers because of its resemblance to the most prominent member of the cucurbitaceae family of plants--the pumpkin. In the intervening years, the fundamental binding properties of CB[6]-high affinity, highly selective, and constrictive binding interactions--have been delineated by the pioneering work of the research groups of Mock, Kim, and Buschmann, and has led to their applications in waste-water remediation, as artificial enzymes, and as molecular switches. More recently, the cucurbit[n]uril family has grown to include homologues (CB[5]-CB[10]), derivatives, congeners, and analogues whose sizes span and exceed the range available with the alpha-, beta-, and gamma-cyclodextrins. Their shapes, solubility, and chemical functionality may now be tailored by synthetic chemistry to play a central role in molecular recognition, self-assembly, and nanotechnology. This Review focuses on the synthesis, recognition properties, and applications of these unique macrocycles.

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Section: Pseudorotaxanes Rotaxanes and Their Oligomeric Analoguesmentioning

confidence: 99%

The Cucurbit[n]uril Family

et al. 2005

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“…35 Å 3 on each side), while a very early prediction has placed this volume as 30 Å 3 31. This is sufficiently large for threading, a property which has been abundantly employed in the construction of rotaxanes 132–135. The isobutyl group is still sufficiently small to thread through the portal,136 while the neopentyl group serves as a permanent stopper in rotaxane architectures 100.…”

Section: Volumes Of the Inner Cavity And Packing Coefficients For mentioning

confidence: 99%

Deep Inside Cucurbiturils: Physical Properties and Volumes of their Inner Cavity Determine the Hydrophobic Driving Force for Host–Guest Complexation

Nau

Florea

Assaf

2011

Israel Journal of Chemistry

337

406

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Cucurbit[n]urils (CBn) bind guest molecules through a combination of electrostatic interactions with the carbonyl rims and hydrophobic interactions with the inner cavity. Investigations with solvatochromic probes in CB7 reveal that the polarity of the cavity resembles that of alcohols (e.g., n‐octanol), while its polarizability (P=0.12) and apparent refractive index (nD=1.10±0.12) are extremely low, close to the gas phase. The calculated molecular quadrupole moments of CBs are extremely large (Θzz=−120 to −340 Buckingham). A survey of reported binding constants of neutral guests and hydrophobic residues that form 1 : 1 inclusion complexes with CB6, reveals a preferential inclusion of C3–C5 residues in its cavity. The largest guests which show non‐negligible binding contain 7 heavy atoms (excluding hydrogen). For CB7, the strongest binding is observed for guests with adamantyl (10 heavy atoms) and ferrocenyl groups (11 heavy atoms), while the largest guests known to be complexed are carborane and the adduct of two pyridine derivatives (12 heavy atoms). The evaluation of different volumes shows that the most meaningful cavity, namely that responsible for binding of hydrophobic residues, is confined by the planes through the oxygen carbonyls. The volume of this inner cavity follows the formula V/Å3=68+62(n−5)+12.5(n−5)2, affording representative cavity volumes of 68 Å3 for CB5, 142 Å3 for CB6, 242 Å3 for CB7, and 367 Å3 for CB8. The volume of the 2 bond dipole regions is comparably smaller, amounting, for example, to 2×35 Å3 for CB6. The analysis of packing coefficients for representative sets of known guests with clearly defined hydrophobic binding motifs reveals average values of 47 % for CB5, 58 % for CB6, 52 % for CB7, and 53 % for CB8, which are well in line with the preferred packing (“55 % solution”, see S. Mecozzi, J. Rebek, Chem. Eur. J. 1998, 4, 1016–1022) in related supramolecular host–guest assemblies. The driving force for binding of hydrophobic guests and residues by CBs is interpreted in terms of the unimportance of dispersion interactions (owing to the low polarizability of their cavity) and the dominance of classical and nonclassical hydrophobic effects related to the removal of very‐high‐energy water molecules (2 for CB5, 4 for CB6, 8 for CB7, and 12 for CB8) from the cavity.

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“…Genau genommen kann jeder CB[ n ]‐Komplex, in dem der Gast aus dem Hohlraum hinausragt, bereits als Pseudorotaxan und damit als Ausgangspunkt für die Synthese von Rotaxanen, Polyrotaxanen und Polypseudorotaxanen angesehen werden 186. In Lösung wurden Rotaxane mit CB[6] auf verschiedenen Wegen erhalten: durch dipolare Cycloadditionen,147, 150–152, 187 Anknüpfung von Dinitrophenyl‐Gruppen als Stopper,188 Amidbindungsknüpfungen,189–193 ionische Wechselwirkungen194 und Koordination von Alkylcobaloximen 195. 196 Die Haupt‐ oder Seitenketten einer Vielzahl von Polymeren, darunter Polyacrylamide und Polystyrole,197 Poly(hexamethylenimine),151, 198 Di‐ und Polyviologene98, 199 und Polypropylenimin‐Dendrimere,200 wurden in CB[6] eingefädelt.…”

Section: Selbstorganisation Mit Cb[n]unclassified

Die Cucurbit[n]uril‐Familie

et al. 2005

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Im Jahre 1981 tauften Mock und Mitarbeiter das makrocyclische methylenverbrückte Glycoluril‐Hexamer (CB[6]) auf den Namen “Cucurbituril” – da ihre Form einem Kürbis ähnelt, dem bekanntesten Mitglied der Cucurbitaceae‐Familie in der Pflanzenwelt. In den folgenden Jahren wurden die grundlegenden Bindungseigenschaften von CB[6] – die hohe Affinität und Selektivität sowie der Einschluss von Gästen – in bahnbrechenden Arbeiten der Gruppen von Mock, Kim und Buschmann aufgezeigt; es folgten Anwendungen in der Wasseraufarbeitung, künstlichen Enzymen und molekularen Schaltern. Erst vor kurzem wuchs die Cucurbit[n]uril‐Familie um Homologe (CB[5]–CB[10]), Derivate, Verwandte und Analoga, sodass sie nun die Molekülgrößen von α‐, β‐ und γ‐Cyclodextrinen umfasst und übersteigt. Auch die Formen, Löslichkeiten und chemischen Funktionalitäten können inzwischen durch spezielle Synthesen den Erfordernissen angepasst werden. Durch diese Eigenschaften sind die Cucurbiturile prädestiniert für eine zentrale Rolle in molekularer Erkennung, Selbstorganisation und Nanotechnologie. Dieser Aufsatz stellt Synthesen, Erkennungseigenschaften und Anwendungen dieser einzigartigen Makrocyclen vor.

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Synthesis of Cucurbituril-spermine-[2]rotaxanes of the Amide-type

Cited by 25 publications

References 27 publications

The Cucurbit[n]uril Family

The Cucurbit[n]uril Family

Deep Inside Cucurbiturils: Physical Properties and Volumes of their Inner Cavity Determine the Hydrophobic Driving Force for Host–Guest Complexation

Die Cucurbit[n]uril‐Familie

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