Video Experimental Relacionado

Updated: Oct 18, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

Solo agrega agua: modulación de la acidez derivada de la estructura de las cápsulas catalíticas de hexameric

David A Poole¹, Simon Mathew¹, Joost N H Reek¹

¹Homogeneous, Supramolecular, and Bioinspired Catalysis Group, van't Hoff Institute for Molecular Science (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands.

Journal of the American Chemical Society

|September 30, 2021

Resumen

Este estudio revela dos formas de la cápsula de undecil-resorcina[4]areno, que difieren en el contenido de agua. La modulación de este contenido de agua aumenta su actividad catalítica para las reacciones de Diels-Alder.

Área de la Ciencia:

Química supramolecular
Catálisis
Física y Química

Sus antecedentes:

La cápsula de undecil-resorcina[4]areno (R) es una superestructura hexámica con un marco cúbico.
Este marco de la cápsula naturalmente incorpora ocho moléculas estructurales de agua.

Objetivo del estudio:

Identificar y caracterizar las especies distintas de la cápsula R en función de la incorporación de agua.
Investigar la influencia del contenido de agua en la estructura supramolecular y la actividad catalítica de la cápsula.

Principales métodos:

Se empleó la espectroscopia de Resonancia Magnética Nuclear (RMN) para estudiar la estructura de la cápsula.
Se utilizaron simulaciones de dinámica molecular clásica (DM) para analizar las interacciones de las moléculas de agua y las redes de enlaces de hidrógeno.
El rendimiento catalítico de diferentes especies de cápsulas se evaluó utilizando un modelo de reacción de ciclización de Diels-Alder.

Principales resultados:

Se identificaron dos especies de cápsulas distintas, R-A (8 moléculas de agua) y R-B (15 moléculas de agua).
La relación entre R-A y R-B en solución puede controlarse ajustando el contenido de agua de la muestra.
La conversión de R-A a R-B aumentó significativamente la velocidad catalítica de una reacción de Diels-Alder en 10 veces.

Conclusiones:

La modulación supramolecular del contenido de agua dentro de las cápsulas R influye en sus propiedades catalíticas.
Este control supramolecular mediado por agua imita los sistemas enzimáticos naturales, lo que demuestra un mecanismo catalítico derivado del cofactor.

Más Videos Relacionados

Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether

Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether

Published on: August 17, 2019

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs

Published on: January 17, 2020

Videos de Conceptos Relacionados

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.

Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis

Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis

Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...

Molecular Structure and Acidity

Molecular Structure and Acidity

An acid can be deprotonated to form a conjugate base or an anion. If the produced anion is more stable, then the acid is stronger. On the contrary, if the anion is unstable, then the acid is weaker. Hence, to determine the acidity of the compound, the stability of its conjugate base is studied using various factors.
The size effect explains the change in atomic size on acidity. When comparing the acids formed from elements that belong to the same column in the periodic table, their atomic sizes...

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...

Acid-Catalyzed Ring-Opening of Epoxides

Acid-Catalyzed Ring-Opening of Epoxides

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...

[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.