Metal-Organic Framework superstructures with long-ranged orientational order via E-field assisted liquid crystal assembly

Kamal Allahyarli; Michael R Reithofer; Fei Cheng; Adam J Young; Endre Kiss; Tristan Tsai Yuan Tan; Alexander Prado-Roller; Jia Min Chin

doi:10.1016/j.jcis.2021.11.151

Metal-Organic Framework superstructures with long-ranged orientational order via E-field assisted liquid crystal assembly

J Colloid Interface Sci. 2022 Mar 15:610:1027-1034. doi: 10.1016/j.jcis.2021.11.151. Epub 2021 Nov 27.

Authors

Kamal Allahyarli¹, Michael R Reithofer², Fei Cheng³, Adam J Young², Endre Kiss⁴, Tristan Tsai Yuan Tan⁵, Alexander Prado-Roller⁶, Jia Min Chin⁷

Affiliations

¹ Faculty of Chemistry, Institute of Physical Chemistry, University of Vienna, Währingerstr. 42, Vienna A-1090, Austria.
² Faculty of Chemistry, Department of Inorganic Chemistry, University of Vienna, Währingerstr. 42, Vienna A-1090, Austria.
³ Department of Chemistry, University of Hull, HU6 7RX, United Kingdom.
⁴ Faculty of Chemistry, Core Facility Multimodal Imaging, University of Vienna, Währingerstr. 38-42, Vienna A-1090, Austria.
⁵ Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, 138634, Singapore.
⁶ Faculty of Chemistry, Department of Inorganic Chemistry - Functional Materials, University of Vienna, Währingerstr. 42, Vienna A-1090, Austria.
⁷ Faculty of Chemistry, Institute of Physical Chemistry, University of Vienna, Währingerstr. 42, Vienna A-1090, Austria. Electronic address: jiamin.chin@univie.ac.at.

PMID: 34920862
DOI: 10.1016/j.jcis.2021.11.151

Abstract

Most MOFs are non-cubic, with functionality dependent upon crystallographic direction, and are largely prepared as microcrystalline powders. Therefore, general methods to orient and assemble free-standing MOF crystals are especially important and urgently needed. This is addressed here through the novel strategy of E-field assisted liquid crystal assembly, applied to MIL-53-NH₂(Al), MIL-68(In) and NU-1000 MOF crystals, with aspect ratios ranging from 10 to 1.2, to form highly oriented MOF superstructures which were photopolymerized to fix their long-ranged order. This new strategy for controlling MOF orientation and packing side-steps the traditional requirements of particle monodispersity, shape homogeneity and high aspect ratios (>4.7) typical of colloidal and liquid crystal assembly, and is applicable even to polydispersed MOF crystals, thereby paving the way towards the development of highly oriented MOF composites with improved functionality.

Keywords: Colloidal assembly; Directed assembly; E-field alignment; Liquid crystals; Metal organic frameworks.