The Coiling Effect in Ether Ionic Liquids: Exploiting Acetate as a Probe for Transport Properties and Microenvironment Analysis

Autor(es)

de Moraes, Beatriz R. ; Paschoal, Vitor H. ; Keppeler, Nicolas ; El Seoud, Omar A. ; Ando, Romulo A.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry B; v. 128, n. 19, p. 11-pg., 2024-04-12.

Resumo

The inherently high viscosity of ionic liquids (ILs) can limit their potential applications. One approach to address this drawback is to modify the cation side chain with ether groups. Herein, we assessed the structure-property relationship by focusing on acetate (OAc), a strongly coordinating anion, with 1,3-dialkylimidazolium cations with different side chains, including alkyl, ether, and hydroxyl functionalized, as well as their combinations. We evaluated their viscosity, thermal stabilities, and microstructure using Raman and infrared (IR) spectroscopies, allied to density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. The viscosity data showed that the ether insertion significantly enhances the fluidity of the ILs, consistent with the coiling effect of the cation chain. Through a combined experimental and theoretical approach, we analyzed how the OAc anion interacts with ether ILs, revealing a characteristic bidentate coordination, particularly in hydroxyl functionalized ILs due to specific hydrogen bonding with the OH group. IR spectroscopy showed subtle shifts in the acidic hydrogens of imidazolium ring C(2)-H and C(4,5)-H, suggesting weaker interactions between OAc and the imidazolium ring in ether-functionalized ILs. Additionally, spatial distribution functions (SDF) and dihedral angle distribution obtained via AIMD confirmed the intramolecular hydrogen bonding due to the coiling effect of the ether side chain. (AU)

• Processo FAPESP: 22/11983-4 - Espectroscopias com intensificação de sinal: nanomateriais, teoria e simulação computacional
• Beneficiário: Mauro Carlos Costa Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 20/09250-3 - Ligações de Hidrogênio em Líquidos Iônicos - Espectroscopia Vibracional e Propriedades Físicas
• Beneficiário: Beatriz Rocha de Moraes
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 16/21070-5 - Espectroscopia vibracional com resolução espacial
• Beneficiário: Mauro Carlos Costa Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Temático