Enhanced hydrogen-transfer catalytic activity of iridium N-heterocyclic carbenes by covalent attachment on carbon nanotubes

Oxidized multiwall carbon nanotubes (CNT) were covalently modified with appropriate hydroxyl-ending imidazolium salts using their carboxylic acid groups. Characterization of the imidazolium-modified samples through typical solid characterization techniques, such as TGA or XPS, allows for the determination of 16 wt % in CNT-1 and 31 wt % in CNT-2 as the amount of the imidazolic fragments in the carbon nanotubes. The imidazolium-functionalized materials were used to prepare nanohybrid materials containing iridium N-heterocyclic carbene (NHC)-type organometallic complexes with efficiencies as high as 95%. The nanotube-supported iridium-NHC materials were active in the heterogeneous iridium-catalyzed hydrogen-transfer reduction of cyclohexanone to cyclohexanol with 2-propanol/KOH as hydrogen source. The iridium hybrid materials are more efficient than related homogeneous catalysts based on acetoxy-functionalized Ir-NHC complexes with initial TOFs up to 5550 h -1. A good recyclability of the catalysts, without any loss of activity, and stability in air was observed. © 2013 American Chemical Society.

Bibliographic Details

Main Authors:	Blanco, Matías, Álvarez Rodríguez, Patricia, Blanco Rodríguez, Clara, Jiménez, M. Victoria, Fernández-Tornos, Javier, Pérez-Torrente, Jesús J., Oro, Luis A., Menéndez López, Rosa María
Other Authors:	Ministerio de Educación, Cultura y Deporte (España)
Format:	artículo biblioteca
Published:	American Chemical Society 2013
Online Access:	http://hdl.handle.net/10261/111183 http://dx.doi.org/10.13039/501100003176 http://dx.doi.org/10.13039/501100004837
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