Video Experimental Relacionado
Updated: Oct 21, 2025
14:11
Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
6.4K
Apertura del anillo mediada por la superficie y deconstrucción de la porfirina a través de la distorsión
Felix Bischoff1, Alexander Riss1, Georg S Michelitsch2
1Physics Department E20, Technical University of Munich, James-Franck Str. 1, 85748 Garching, Germany.
Journal of the American Chemical Society
|September 2, 2021
Resumen
Los investigadores desarrollaron un método químico de superficie para descomponer las porfirinas, un tipo de compuesto macrocíclico. Este proceso elimina selectivamente una unidad de pirrol, creando un derivado de tripirrina en una superficie de cobre.
Área de la Ciencia:
- Química de las superficies
- Química orgánica
- Ciencias de los materiales
Sus antecedentes:
- La descomposición de los compuestos macrocíclicos es crucial en los procesos biológicos y químicos.
- La apertura del anillo inducida por oxigenación es una vía común para estas reacciones.
Objetivo del estudio:
- Introducir una nueva vía química de superficie para la apertura selectiva del anillo de porfirina.
- Investigar el mecanismo y los productos de esta reacción a nivel atómico.
Principales métodos:
- Se utilizan condiciones de vacío ultraalto (UHV) y temperaturas moderadas.
- Se empleó microscopía de fuerza atómica con resolución de enlace (BR-AFM) para la caracterización a nivel atómico.
- Se investigó la interacción de la porfirina con un soporte de cobre para lograr una conformación molecular específica.
Principales resultados:
- Se ha logrado la escisión selectiva de una porfirina, dando como resultado un derivado de la tripirina.
- Intermedios y subproductos de reacción identificados mediante el BR-AFM.
- Racionalizó el mecanismo de apertura del anillo a través de la distorsión conformacional y redujo la estabilidad del macrociclo.
Conclusiones:
- Demostró un método asistido por la superficie para controlar la descomposición de compuestos macrocíclicos.
- Las vías abiertas para dirigir las reacciones de apertura del anillo a través del diseño conformacional.
- Permitió el estudio de los análogos catabólicos del tetrapirrol en las superficies.
Más Videos Relacionados
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Videos de Conceptos Relacionados
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
2.8K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
2.8K
02:26Base-Catalyzed Ring-Opening of Epoxides
9.0K
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
9.0K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.5K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.5K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.0K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.0K
02:24Acid-Catalyzed Ring-Opening of Epoxides
7.8K
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...
7.8K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.2K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.2K