A Synthetic Receptor for Choline and Carnitine

Ballester, Pablo; Shivanyuk, Alexander; Far, Adel Rafai; Rebek, Julius

doi:10.1021/ja0282689

Cited by 82 publications

(60 citation statements)

References 16 publications

(16 reference statements)

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“…The data complement a previous 1 H NMR investigation by Lehn et al [11] A similar data set of binding constants was recently reported by Rebek and co-workers for resorcinarenerelated cavitands as macrocyclic hosts. [43] As can be seen from the experimental data, there is little discrimination by CX4 between acetylated, carbamoylated, and unsubstituted choline, presumably because the substituted group of the guest (R in Scheme 1) remains exposed to the aqueous bulk and carries no charge for all three derivatives.…”

Section: Full Papermentioning

confidence: 99%

Fluorescence Regeneration as a Signaling Principle for Choline and Carnitine Binding: A Refined Supramolecular Sensor System Based on a Fluorescent Azoalkane

Bakirci

Nau

2005

Adv Funct Materials

127

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The fluorescent azoalkane, 2,3‐diazabicyclo[2.2.2]oct‐2‐ene (DBO), forms inclusion complexes with p‐sulfonatocalix[4]arene (CX4). The binding constants are on the order of 103 M–1 in water. The addition of CX4 to DBO solutions results in an efficient fluorescence quenching (up to 90 %). This supramolecular system can be used as a truly water‐soluble sensor system to signal the binding of organic ammonium ions over a large pH range. Addition of choline and carnitine derivatives and tetraalkylammonium ions results in regeneration of this fluorescence, from which the binding constants (KC = 103–105 M–1) are calculated by means of a competitive complexation model. Electrostatic effects are observed, namely, a more‐than‐one order of magnitude weaker binding of the carnitines in neutral solution.

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Section: Full Papermentioning

confidence: 99%

Fluorescence Regeneration as a Signaling Principle for Choline and Carnitine Binding: A Refined Supramolecular Sensor System Based on a Fluorescent Azoalkane

Bakirci

Nau

2005

Adv Funct Materials

127

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“…Entsprechend haben Diederich et al nachgewiesen, dass der Tetraamidinium-Cavitand 54 in Wasser ein sehr guter Rezeptor für Benzoldicarboxylate und Nucleotide ist. [141] [142][143][144][145] Ammonium- [146,147] oder Aminogruppen [148] erreicht. Der Cavitand 55 (R = -CH 2 [143] Die hydrophobe Adamantaneinheit ist bei diesen Komplexen tief im Innern des Hohlraums gebunden, während die primären Aminogruppen zum Tetracarboxylatrand und zum Lösungsmittel hin gerichtet sind.…”

Section: Cavitandenunclassified

Supramolekulare Chemie in Wasser

2007

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Die supramolekulare Chemie in Wasser ist ein ständig wachsendes Forschungsgebiet, da nichtkovalente Wechselwirkungen in wässrigen Medien entscheidend für ein besseres Verständnis und die Kontrolle grundlegender Prozesse in der Natur sind. Dieser Aufsatz bietet einen Überblick über aktuelle Entwicklungen auf den Gebieten der wasserlöslichen synthetischen Rezeptoren, der Selbstorganisation und der molekularen Erkennung in Wasser unter Berücksichtigung von Funktionalitäten, die zur Verbesserung der Wasserlöslichkeit eingeführt werden, sowie der supramolekularen Wechselwirkungen und der Methoden, die für eine effiziente Gasterkennung und Selbstorganisation in Wasser eingesetzt werden. Zudem beschreibt er die besonderen Eigenschaften und Anwendungsmöglichkeiten supramolekularer Einheiten in wässrigen Medien.

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“…These benzimidazoles can be stabilized in their vase shapes by small molecules such as water or methanol that offer both hydrogen bond donors and acceptors that are necessary to complete the cyclic seam of hydrogen bonds. Even the parent octaamines 3 have recognition properties when solvents with strong hydrogen bond acceptors [DMSO and dimethylformamide (DMF)] are present to complete the hydrogen-bonding seam (21).…”

Section: Synthesismentioning

confidence: 99%

“…We were also surprised to find that the octamines 3 had a complexation chemistry of their own (21). Ordinarily, benzene rings with many electron-releasing substituents are unstable toward air oxidation, so we had used these molecules as rapidly as we had made them.…”

Section: Chemistrymentioning

confidence: 99%

Functional cavitands: Chemical reactivity in structured environments

Purse

Rebek

2005

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

156

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Container-shaped molecules provide structured environments that impart geometric bounds on the motions and conformations of smaller molecular occupants. Moreover, they provide ''solvation'' that is constrained in time and space. When inwardly directed functional groups are present, they can interact chemically with the occupants. Additionally, the potential for reactivity and catalysis is greatly enhanced. Deep cavitands, derived from resorcinarenes, nearly surround smaller molecules and have been one of the most successful platforms for elaboration with functional groups. Derivatives bearing organic and metal-binding functional groups have been shown to affect recognition properties and selectively accelerate diverse reactions. In this review, we examine recent examples of these systems with an emphasis on how and why ordered nanoenvironments impart changes in the properties and reactivity of their occupants.nanoenvironments ͉ supramolecular M olecular recognition became a popular theme in physical organic chemistry during the late 1980s, and many of those studies evaluated intermolecular forces as models for biochemical phenomena. Synthetic receptors of increasing sophistication such as clefts (1), armatures (2), tweezers (3), bowls (4), and other vehicles (5, 6) were devised for the study of reversible interactions, both in aqueous and nonaqueous media. The emergence of site-directed mutagenesis replaced much of this activity. The strength of a hydrogen bond inside, say, an enzyme can be determined in situ through substitution of an unnatural amino acid (7) with the appropriate functional groups. In addition, enzymes, aptamers, ribozymes, and catalytic antibodies can fold more or less completely around a target molecule. This creates a structured environment for the functional group interactions in question, a feature missing in the various concave structures invented by synthetic chemists. A receptor that completely and reversibly encapsulated sizable molecules was prepared in 1995 (8), but it lacked any appropriately positioned functionality. It took us another 5 years to synthesize a receptor that could, more or less, surround a target molecule and present it with a reactive functional group. This led to changes in reactivity of the sort encountered in the macromolecular complexes of biology. We do not intend here to promote these as model systems. Instead, this review is concerned with effects of physical restraints on a molecule surrounded by another; the physical organic chemistry of structured environments. More specifically, the structures are specially modified cavitands, macrocyclic compounds featuring a cavity that is sealed at one end and functionalized at the other. Cavitands have a long history in studies of molecular recognition, and several reviews are available that cover the literature up to 2002 (9-13). With rare exceptions, these cavitands offer only spaces to be filled by smaller molecules. Our departure was their functionalization with groups that are directed at the molecules held tempo...

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A Synthetic Receptor for Choline and Carnitine

Cited by 82 publications

References 16 publications

Fluorescence Regeneration as a Signaling Principle for Choline and Carnitine Binding: A Refined Supramolecular Sensor System Based on a Fluorescent Azoalkane

Fluorescence Regeneration as a Signaling Principle for Choline and Carnitine Binding: A Refined Supramolecular Sensor System Based on a Fluorescent Azoalkane

Supramolekulare Chemie in Wasser

Functional cavitands: Chemical reactivity in structured environments

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