Video Experimental Relacionado

Updated: Jul 31, 2025

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Published on: May 21, 2019

Benzimidazolios sustituidos por triarilamina como fotocatalizadores de tipo díado receptor-donante de electrones para

Ryo Miyajima¹, Yuuki Ooe¹, Tomoaki Miura¹

¹Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan.

Journal of the American Chemical Society

|May 2, 2023

Resumen

Las nuevas moléculas donantes de electrones, los benzimidazolios sustituidos por triarilamina, muestran una actividad fotocatalítica prometedora para las transformaciones orgánicas reductivas. Un intermedio clave facilita la transferencia de electrones, con un análogo sustituido por bromo que muestra un rendimiento catalítico superior.

Área de la Ciencia:

Química orgánica
Fotocatálisis
Ciencias de los materiales

Sus antecedentes:

Las moléculas de díada donante-aceptora de electrones son cruciales en la fotocatálisis.
Los compuestos de benzimidazolio ofrecen propiedades electrónicas sintonizables.
El desarrollo de fotocatalizadores eficientes para transformaciones reductivas es un desafío continuo.

Objetivo del estudio:

Sintetizar y caracterizar nuevas moléculas de benzimidazolio sustituidas por triarilamina.
Investigar su potencial fotocatalítico para las transformaciones orgánicas reductivas.
Para aclarar el mecanismo de la fotocatálisis.

Principales métodos:

Síntesis de benzimidazolios sustituidos por triarilamina (BI+-PhNAr2).
Evaluación de la actividad fotocatalítica mediante técnicas espectroscópicas (absorción, fluorescencia, absorción transitoria) y mediciones del potencial redox.
Cálculos de la teoría funcional de la densidad (DFT).
Estudios mecanicistas que incluyen reducción de sustrato y agentes cooperativos.

Principales resultados:

La transferencia de electrones intramolecular inducida por la foto en BI⁺-PhNAr₂ genera un estado de carga desplazada de larga duración (BI^•-PhN^•+Ar₂).
Este intermedio facilita la fotocatálisis mediante la transferencia de un solo electrón con un agente cooperativo (BIH-Ph).
El análogo BI⁺-PhN(C₆H₄Br-p) ₂ exhibió el rendimiento catalítico más consistente.

Conclusiones:

Los benzimidazolios sustituidos por triarilamina son fotocatalizadores eficaces para las transformaciones orgánicas reductivas.
El mecanismo implica un estado de carga desplazada de larga duración y una transferencia de electrones cooperativa.
Las modificaciones estructurales, como la sustitución de bromo, pueden mejorar la eficiencia catalítica.

Más Videos Relacionados

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

Published on: July 17, 2020

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Published on: July 30, 2017

Videos de Conceptos Relacionados

Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence of a Lewis acid catalyst to give halogenated substitution products. A Lewis acid such as aluminium chloride or ferric chloride catalyzes the chlorination, and ferric bromide catalyzes the bromination reactions. During the bromination of alkenes, bromine polarizes and becomes electrophilic. However, in the bromination of benzene, the bromine...

Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene

Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene

Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.

Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...

Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic S_N1

Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

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