Highly modulated supported triazolium-based ionic liquids: direct control of the electronic environment on Cu nanoparticles
Date
2020-03-01Author
Valdebenito, Cristian [Chile. Universidad Mayor. Facultad de Ciencias. Centro de Nanotecnología Aplicada]
Pinto, José
Nazarkovsky, Michael
Chacón, Gustavo
Martínez-Ferrate, Oriol
Wrighton-Araneda, Kerry
Cortés-Arriagada, Diego
Camarada, María Belen [Chile. Universidad Mayor. Facultad de Ciencias. Centro de Nanotecnología Aplicada]
Fernandes, Alves Jesum
Abarca, Gabriel [Chile. Universidad Mayor. Facultad de Ciencias. Centro de Nanotecnología Aplicada]
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Abstract
A series of new triazolium-based supported ionic liquids (SILPs), decorated with Cu NPs, were successfully prepared and applied to the N-arylation of aryl halides with anilines. The triazoles moieties were functionalised using copper-catalysed azide-alkyne cycloaddition. SILP surface characterisation showed a strong correlation between the triazolium cation volume and textural properties. STEM images showed well-dispersed Cu NPs on SILPs with a mean diameter varying from 3.6 to 4.6 nm depending on the triazolium cation used. Besides, XPS results suggest that the Cu(0)/Cu(i) ratio can be modulated by the electronic density of triazolium substituents. XPS and computational analysis gave mechanistic insights into the Cu NP stabilisation pathways, where the presence of electron-rich groups attached to a triazolium ring plays a critical role in leading to a cation adsorption pathway (E-ads = 72 kcal mol(-1)). In contrast, less electron-rich groups favour the anion adsorption pathway (E-ads = 63 kcal mol(-1)). The Cu@SILP composite with electron-rich groups showed the highest activity for the C-N Ullmann coupling reaction, which suggests that electron-rich groups might act as an electron-like reservoir to facilitate oxidative addition for N-arylation. This strategy firmly suggests the strong dependence of the nature of triazolium-based SILPs on the Cu NP surface active sites, which may provide a new environment to confine and stabilise MNPs for catalytic applications.
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http://repositorio.umayor.cl/xmlui/handle/sibum/7356https://pubs.rsc.org/en/content/articlepdf/2020/na/d0na00055h
https://doi.org/10.1039/D0NA00055H
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