Highly modulated supported triazolium-based ionic liquids: direct control of the electronic environment on Cu nanoparticles

• Published in: Nanoscale advances Vol. 2; no. 3; pp. 1325 - 1332
• Main Authors: Valdebenito, Cristián, Pinto, Jose, Nazarkovsky, Michael, Chacón, Gustavo, Martínez-Ferraté, Oriol, Wrighton-Araneda, Kerry, Cortés-Arriagada, Diego, Camarada, María Belén, Alves Fernandes, Jesum, Abarca, Gabriel
• Format: Journal Article
• Language: English
• Published: RSC 17.03.2020
• Subjects: Chemistry
• ISSN: 2516-0230; 2516-0230
• DOI: 10.1039/d0na00055h

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. 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.