The synthesis of [2], [3] and [4]rotaxanes and semirotaxanes

Tuncel, Dönüş; Steinke, Joachim H. G.

doi:10.1039/b109256c

Cited by 96 publications

(58 citation statements)

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“…The reaction also displays several features that are commonly observed in enzymatic reactions, namely: 1) reaching a limit in the reaction rate at high concentrations of 38 and 39, 2) product release from CB [6]·40 is rate-limiting, 3) inhibition of the substrate through formation of nonproductive termolecular complex CB [6]·38·38, and 4) competitive inhibition by nonreactive substrate analogues. Steinkes research group has used the CB [6]-promoted dipolar cycloadditon of azides and terminal acetylenes for the preparation of catalytically selfthreading rotaxanes, [150,151] [2]-, [3]-, and [4]-rotaxanes and pseudorotaxanes, [152] as well as oligotriazoles. [153] 6.2.…”

Section: Catalysismentioning

confidence: 99%

“…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%

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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: Catalysismentioning

confidence: 99%

Section: Pseudorotaxanes Rotaxanes and Their Oligomeric Analoguesmentioning

confidence: 99%

The Cucurbit[n]uril Family

et al. 2005

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“…Starting from a previous discovery [68,69] that either preorganizational effects as well as the cationic nature of cucurbituril can effect an efficient azide/alkyne click process, Tuncel and Steinke [70] have prepared rotaxanes wherein the cucurbituril moiety serves either as catalyst as well as a rotaxane-part during an azide/alkyne click reaction. Higher rotaxanes are also accessible using bifunctional building blocks as well as under generation of rotaxanes with a pH-responsive moiety.…”

Section: Rotaxanes P-cyclophanes and Calixarenesmentioning

confidence: 99%

‘Click’ Chemistry in Polymer and Materials Science

Binder

Sachsenhofer

2007

Macromol. Rapid Commun.

1,480

866

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IntroductionThe azide/alkyne 'click' reaction [1] (also termed the Sharpless 'click' reaction) is a recent re-discovery of a reaction fulfilling many requirements for the affixation of ligands onto polymers by post-modification processes, which include a) often quantitative yields, b) a high tolerance of functional groups, c) an insensitivity of the reaction to solvents, irrespective of their protic/aprotic or polar/ non-polar character, and d) reactions at various types of interfaces, such as solid/liquid, liquid/liquid, or even solid/ solid interfaces. The present review focuses on issues related to the reaction itself as well as on the wide applications in polymer science, material, and surface science.The basic reaction, which is nowadays summed up under the name 'Sharpless-type click reaction', is a variant of the Huisgen 1,3-dipolar cycloaddition reaction [2a,2b] between C-C triple, C-N triple bonds, and alkyl-/aryl-/ sulfonyl azides (see Scheme 1).The relevant outcomes of this reaction are tetrazoles, 1,2,3-triazoles, or 1,2-oxazoles (Scheme 1a-c, respectively). Besides the 1,3-dipolar cycloaddition reaction, classical Diels-Alder-type reactions (Scheme 1d) have been used extensively for the functionalization of polymeric materials and surfaces. [3] These reactions are located within a series of reactions named click reactions, which is defined by a gain of thermodynamic enthalpy of at least 20 kcal Á mol À1 , [1] thus leading to reactions characterized by high yields, simple reaction conditions, fast reaction times, and high selectivity. Among many reactions tested, the 1,3-dipolar cycloaddition process has emerged as the method of choice to effect the requirements of ligating two ReviewThe modification of polymers after the successful achievement of a polymerization process represents an important task in macromolecular science. Cycloaddition reactions, among them the metal catalyzed azide/alkyne 'click' reaction (a variation of the Huisgen 1,3-dipolar cycloaddition reaction between terminal acetylenes and azides) represents an important contribution towards this endeavor. They combine high efficiency (usually above 95%) with a high tolerance of functional groups and solvents, as well as moderate reaction temperatures (25-70 8C). The present review assembles recent literature for applications of this reaction in the field of polymer science (linear polymers, dendrimers, gels) as well as the use of this and related reactions for surface modification on carbon nanotubes, fullerenes, and on solid substrates, and includes the authors own publications in this field. A number of references (>100) are included.

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“…Após a formação destes pseudo-rotaxanos é possível ligar tais grupos, criando travas nestes eixos, tornando estáveis estas estruturas supramoleculares (Figuras 5c, d). A maioria dos métodos de síntese são essencialmente variantes deste 65,[78][79][80][81] .…”

Section: Rotaxanos Pseudo-rotaxanos Rolamentos E Chaveadores Molecuunclassified

Cucurbiturilas

Demets¹

2007

Quím. Nova

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Recebido em 7/8/06; aceito em 9/11/06; publicado na web em 17/7/07 CUCURBITURILS. This review article describes the properties and the main applications of the glicol[n]urils. These compounds are cavitands made of n glycolurilic units arranged in circles, giving rise to extremely symmetric toroidal molecules. The cucurbit [n]urils create this way variable-sized hydrophobic cavities and the glycolurilic carbonyles delimit two portals on these cavities, slightly narrower than their internal radii. Their structure, physical and chemical properties favor the formation of inclusion compounds, and turn them into important building blocks for supramolecular chemistry and nanotechnology.Keywords: cucurbiturils; cucurbitands; inclusion compounds. INTRODUÇÃOAs cucurbiturilas foram sintetizadas pela primeira vez por Behrend e colaboradores 1 em 1905, como resultado da condensação da uréia e do glioxal, formando glicolurila e análogos poliméricos na presença de formaldeído. A tecnologia da época não permitiu uma caracterização inequívoca e a estrutura peculiar destes polímeros só foi elucidada pelo grupo de Mock, 80 anos mais tarde 2 . Pela primeira vez demonstrou-se que os cucurbitandos, outra designação desta família de compostos (abreviados também por CB[n]), eram estruturas cíclicas toroidais, compostas por 6 unidades de glicolurila, ligadas por grupos -CH 2 -em suas aminas de simetria D 6H (Figura 1).A nomenclatura oficial deste composto é complexa* e a sua forma de abóbora deu origem a seu nome, de cucurbita em latim (* segundo a IUPAC, o nome da cucurbit[6]urila ou CB[6] seria: dodecaidro-1H, 4H, 14H, 17H-2, 16:3, 15-dimetano-5H, 6H, 7H, 8H, 9H, 10H, 11H, 12H, 13H, 18H, 19H, 20H, 21H, 22H, 23H, 24H, 25H, 26H-2, 3-4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, 12a, 13a, 15, 16, 17a, 18a, 19a, 20a, 21a, 22a, 23a, 24a, 2 -3 -5a, 26a -tetracosaazabispentaleno[1''',6''':5'',6'',7'']cicloocta[1'', 2'', 3'':3', 4']pentaleno(1',6':5,6,7)cicloocta(1,2,3-gh:1',2',3'-g'h')cicloocta(1, 2, 3-cd:5, 6, 7-c'd')dipentaleno-1, 4, 6, 8, 10, 12, 14, 17, 19, 21, 23, 25-dodecona).Esta estrutura, além de ser simétrica, possui uma cavidade central hidrofóbica relativamente grande, que é capaz de acomodar espécies variadas para a formação de compostos de inclusão, também chamados de caviplexos, como o fazem outras famílias de cavitandos como as ciclodextrinas ou calixarenos. Na cucurbit[6]urila, existem 12 carbonilas orientadas para fora das cavidades, 6 de cada lado, formando assim dois portais para as cavidades, e conferindo à molé-cula um caráter básico de Lewis. Os métodos mais modernos de análise constataram que não eram formados apenas anéis de 6 membros nas sínteses de cucurbiturilas, mas que outros análogos cíclicos com 5 a 11 unidades glicolurílicas também eram formados durante as sínteses. Os recentes avanços em química orgânica sintética permitiram a elaboração de novas rotas, resultando em rendimentos diferenciados na produção destes homólogos. O maior controle sobre a distribuição dos produtos síntese tornou viável a síntese de CB [7] e ...

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The synthesis of [2], [3] and [4]rotaxanes and semirotaxanes

Abstract: The cucurbituril-catalysed synthesis of [2], [3] and [4]semirotaxanes allows access to regioselectively pure, 1,3-disubstituted mono-, bis- and tris-triazoles in high yield after dethreading.

Cited by 96 publications

References 13 publications

The Cucurbit[n]uril Family

The Cucurbit[n]uril Family

‘Click’ Chemistry in Polymer and Materials Science

Cucurbiturilas

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