Impact of Anions on the Partition Constant, Self-Diffusion, Thermal Stability, and Toxicity of Dicationic Ionic Liquids

Clarissa P Frizzo; Caroline R Bender; Paulo R S Salbego; Carla A A Farias; Thayanara C da Silva; Sílvio T Stefanello; Tássia L da Silveira; Félix A A Soares; Marcos A Villetti; Marcos A P Martins

doi:10.1021/acsomega.7b01873

Impact of Anions on the Partition Constant, Self-Diffusion, Thermal Stability, and Toxicity of Dicationic Ionic Liquids

ACS Omega. 2018 Jan 31;3(1):734-743. doi: 10.1021/acsomega.7b01873. Epub 2018 Jan 22.

Affiliation

¹ Núcleo de Química de Heterociclos (NUQUIMHE), Department of Chemistry, Department of Biochemistry and Molecular Biology, and Laboratório de Espectroscopia e Polímeros (LEPOL), Department of Physics, Federal University of Santa Maria (UFSM), CEP 97105-900 Santa Maria, RS, Brazil.

Abstract

Partition constants (K_D^°), molecular dynamics (T₁, T₂, and DOSY measurements), thermal stability, and toxicity of dicationic ionic liquids (ILs) were determined. The dicationic ILs derived from 1,n-bis(3-methylimidazolim-1-yl)octane, [BisOct(MIM)₂][2X] (in which X = Cl, Br, NO₃, SCN, BF₄, and NTf₂), were evaluated to verify the influence of anion structure on the IL properties. A monocationic IL [Oct(MIM)][Br] was also monitored for comparison. In general, the solubility of the ILs followed the anion free energy of hydration (ΔG°_hyd). The thermokinetic and thermodynamic functions of activation of the ILs were determined via thermogravimetric data, and it was observed that polyatomic anions influence the decomposition mechanism of these IL structures. Furthermore, [Oct(MIM)][Br] had a decomposition rate greater than that of the dicationic analogue, and the thermodynamic parameters of activation data corroborate these results. Finally, the dicationic ILs did not indicate toxic effects (LD₅₀ > 40 mM).