Host–guest complexes of cucurbituril with the 4-methylbenzylammonium lon, alkali-metal cations and NH<sub>4</sub><sup>+</sup>

Hoffmann, Rüdiger; Knoche, Wilhelm; Fenn, Christian; Buschmann, Hans‐Jürgen

doi:10.1039/ft9949001507

Cited by 136 publications

(164 citation statements)

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“…13 Kinetic measurements indicated that 4-methylbenzylammonium produces with CB6 not only inclusion but also exclusion complexes. 14 In the latter, the ammonium group interacts with one of the polar portals of the host and the aromatic moiety extends into the solvent. The equilibrium for the inclusion of protonated cyclohexylmethylamine in CB6 was reached only after several days, whereas the rates of ingression and egression were much faster for the unprotonated amine.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Miskolczy

Biczók

2014

J. Phys. Chem. B

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Section: Introductionmentioning

confidence: 99%

“…[14][15][16][17] Yu and coworkers found that the dissociation of neutral guests occurs in one step from CB7, but ammonium cyclohexyl derivatives egress in multi-step processes. 29 The hydrophobic, ion-dipole and hydrogen bonding interactions are the strongest in different guest positions in CB7.…”

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confidence: 99%

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Miskolczy

Biczók

2014

J. Phys. Chem. B

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“…Desta forma, os cucurbitandos são capazes de formar compostos de inclusão, complexos e adutos com uma enorme variedade de espécies quí-micas 35,36 . Podemos citar entre elas as aminas 12,14,34,[37][38][39] , compostos aromáticos 40,41 , heterocíclicos [42][43][44] , viologênios [44][45][46][47][48][49] , poliaminas, peptídios e aminoácidos [50][51][52] , álcoóis 50,53,54 , surfatantes 53,55 , tióis, gases como CO 2 , O 2 , Kr, N 2 e Xe 31,32,56-58 , metais, complexos e muitas outras, como corantes 59,60 e fármacos [59][60][61][62] (Tabela 2). Em termos de constantes de formação médias de caviplexos de CB [6] com um grande número de compostos, como álcoóis por exemplo, são geralmente uma ordem de grandeza superiores às obtidas com α-ciclodextrinas, mostrando que também exibem uma grande afinidade por moléculas neutras, além de maior seletividade por conta dos fatores mencionados anteriormente.…”

Section: Compostos De Inclusão Com Cucurbitandosunclassified

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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“…S-shaped oligomers II-5 and II-6 yield CB [5] and CB [6] Behrend's report and disclosed the remarkable macrocyclic structure comprising six glycoluril units and twelve methylene bridges and dubbed it cucurbituril in recognition of its resemblance to a pumpkin which is a prominent member of the cucurbitaceae family ( Figure 1). 2 We refer to cucurbituril as cucurbit [6]uril and abbreviate this as CB [6] In contrast to the host-guest chemistry of -, -, and -cyclodextrin which has developed steadily over the past century, the supramolecular chemistry of CB [6] only began to develop in the 1980's and 1990's due to the pioneering work of Mock, 3 Buschmann, 4 and Kim. 5,6 Interest in the CB[n] family has increased dramatically in the new millennium following the preparation of four new CB[n] homologues (CB [5], CB [7], CB [8], and CB [10]•CB [5]) by the groups of Kim and Day.…”

Section: List Of Figuresmentioning

confidence: 99%

“…1 Figure 2. Chemical structures of -, -, and -cyclodextrin, 18-crown-6, and a calix [4]arene. 3 Figure 3.…”

Section: List Of Figuresmentioning

confidence: 99%

Cucurbit[n]uril Analogues.

2004

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Molecular recognition and self-assembly in aqueous solution have experienced rapid growth in recent years. The use of -, -, and -cyclodextrins, calixarenes, and cyclophanes have served as the platforms for molecular recognition in aqueous solution. Recently, the investigation of an alternative platform based on cucurbituril has become the focus of several research groups. The rigid structure and capability of forming complexes with molecules and ions through hydrophobic, iondipole and hydrogen-bonding interactions make cucurbituril an attractive candidate as a synthetic receptor as well as a building block for the construction of supramolecular architectures.However, before cucurbituril can be used to supplant the more common platforms as the molecule of choice for molecular recognition and self-assembly in aqueous solution, several advances must be made: 1) cucurbiturils must become available in a variety of sizes, 2) their solubility must be improved, and 3) synthetic procedures must be advanced to include the ability to selectively generate specific cucurbituril homologues, derivatives, and analogues. To help rationalize the high yields obtained in these macrocyclization reactions, we performed mechanistic studies of model methylene bridged glycoluril dimers.The molecular recognition properties of a water soluble cucurbit[6]uril analogue in aqueous buffer toward a variety of guests including alkanediamines, aromatics, amino acids, and nucleobases were studied by fluorescence spectroscopy.For the alkanediamines studied, as the length of the alkane is increased between the amines, the association constants also increase. The CB [6] analogue is capable of forming strong complexes with guests containing aromatic rings with association constants (K a ) ranging from 10 2 to 10 6 M -1 due to the favorable -interactions that occur between the host and the aromatic portion of the guest while encapsulated in its hydrophobic cavity. CUCURBIT[N]URIL ANALOGUES

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Host–guest complexes of cucurbituril with the 4-methylbenzylammonium lon, alkali-metal cations and NH₄⁺

Cited by 136 publications

References 10 publications

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Cucurbiturilas

Cucurbit[n]uril Analogues.

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Host–guest complexes of cucurbituril with the 4-methylbenzylammonium lon, alkali-metal cations and NH4+

Cited by 136 publications

References 10 publications

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Cucurbiturilas

Cucurbit[n]uril Analogues.

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Host–guest complexes of cucurbituril with the 4-methylbenzylammonium lon, alkali-metal cations and NH₄⁺