Physicochemical properties and density functional theory calculation of octahedral UiO-66 with Bis(Trifluoromethanesulfonyl)imide ionic liquids

Mohd Faridzuan Majid; Hayyiratul Fatimah Mohd Zaid; Muhammad Fadhlullah Abd Shukur; Azizan Ahmad; Khairulazhar Jumbri

doi:10.1016/j.heliyon.2023.e20743

Physicochemical properties and density functional theory calculation of octahedral UiO-66 with Bis(Trifluoromethanesulfonyl)imide ionic liquids

Heliyon. 2023 Oct 6;9(10):e20743. doi: 10.1016/j.heliyon.2023.e20743. eCollection 2023 Oct.

Authors

Mohd Faridzuan Majid^{1

2}, Hayyiratul Fatimah Mohd Zaid^{3

2}, Muhammad Fadhlullah Abd Shukur^{1

2}, Azizan Ahmad^{4

5}, Khairulazhar Jumbri^{1

6}

Affiliations

¹ Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak Darul Ridzuan, Malaysia.
² Centre of Innovative Nanostructures & Nanodevices (COINN), Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak Darul Ridzuan, Malaysia.
³ Chemical Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, 32610, Perak Darul Ridzuan, Malaysia.
⁴ Department of Chemical Sciences, Universiti Kebangsaan Malaysia, Bangi, 43600, Selangor, Malaysia.
⁵ Department of Physics, Faculty of Science and Technology, Airlangga University (Campus C), Mulyorejo Road, Surabaya, 60115, Indonesia.
⁶ Centre for Research in Ionic Liquids (CORIL), Universiti Teknologi PETRONAS, 32610, Seri Iskandar, Perak Darul Ridzuan, Malaysia.

Abstract

In this study, the physicochemical properties and molecular interactions between zirconium-based metal-organic framework (UiO-66) and three different ionic liquids based on bis(trifluoromethanesulfonyl)imide anion (EMIM⁺, BMIM⁺ and OMIM⁺) was performed via a combined experimental and computational approach. The ionic liquid loaded UiO-66 or IL@UiO-66 was synthesized and characterized to understand the host-guest interaction. Density functional theory calculation was performed to analyse the electronic structure of IL@UiO-66 to provide molecular insight on the dominant interactions occurred in the hybrid material. Results showed that all ILs were successfully incorporated into the micropores of UiO-66. The 3D framework was retained even after loaded with ILs as analyzed from XRD pattern. FTIR spectrum reveals that interactions of ILs with UiO-66 influenced by the alkyl chain length of the cation. The anion has a profound affinity with the UiO-66 due to the presence of electronegative atoms. Phase transition study from DSC suggested that the incorporation of ILs has stabilized the framework of UiO-66 by shifting the endothermic peak to a higher state. These findings were further elaborated with DFT calculation. Geometrical optimizations confirmed the structural parameter changes of UiO-66 when loaded with ILs. These was mainly contributed by the non-covalent interactions which was confirmed by the reduced density gradient scattered plot. Another important findings are the strength of hydrogen bonding at the host-guest interface was influenced by the alkyl chain length. The molecular orbital analysis also shows that the size of alkyl chain influence the reactivity of the hybrid material. The present study provides fundamental insights on the molecular interaction of UiO-66 and ILs as a hybrid material, which can open new possibilities for advanced material for metal-organic framework applications in energy storage system, catalysis, gas storage and medicinal chemistry.

Keywords: Cluster model; DFT; Ionic liquids; Metal-organic framework; Molecular orbital.