Controlled partial interpenetration in metal–organic frameworks

Abstract

Interpenetration, the entwining of multiple lattices, is a common phenomenon in metal-organic frameworks (MOFs). Typically, in interpenetrated MOFs the sub-lattices are fully occupied. Here we report a family of MOFs in which one sub-lattice is fully occupied and the occupancy level of the other can be controlled during synthesis to produce frameworks with variable levels of partial interpenetration. We also report an 'autocatenation' process, a transformation of non-interpenetrated lattices into doubly interpenetrated frameworks via progressively higher degrees of interpenetration that involves no external reagents. Autocatenation maintains crystallinity and can be triggered either thermally or by shear forces. The ligand used to construct these MOFs is chiral, and both racemic and enantiopure partially interpenetrated frameworks can be accessed. X-ray diffraction, nonlinear optical microscopy and theoretical calculations offer insights into the structures and dynamic behaviour of these materials and the growth mechanisms of interpenetrated MOFs.

Controlling interpenetration through linker conformation in the modulated synthesis of Sc metal–organic frameworks

“…Ligand twisting is a prerequisite for the p-stacking interactions by allowing them to become correctly aligned and we believe this stabilising interaction is one of the driving forces for the formation of a two-fold interpenetrated structure; p-stacking has previously been determined as the driving force for full and partial interpenetration in Zn 2+ MOFs of substituted bpdc ligands. 22 In contrast, the bpydc ligands in the solid-state structure of 2-HCl are effectively co-planar with an average torsion angle of 0.5 ( Fig. 6b), a conformation which is expected to be more energetically favourable for bpydc than the twisted arrangement that is necessary to form the interpenetrated structure of 1, and may explain the formation of 2 instead.…”

“…As such, attempts have been made to control interpenetration through inuencing parameters including ligand length, 17 pendant functionality 18,19 and synthesis conditions, [20][21][22] while in extreme cases MOFs with certain topologies (e.g. rht) cannot interpenetrate.…”

Porous Metal‐Organic Polyhedral Framework containing Cuboctahedron Cages as SBUs with High Affinity for H2 and CO2 Sorption: A Heterogeneous Catalyst for Chemical Fixation of CO2

“…The double interpenetration of such huge cluster-containing nets providesahigh density of open metal sites, due to which it exhibits remarkable H 2 storagec apacity (313 cm 3 g À1 at 1bar and7 7K)a sw ell as high CO 2 capture ability (159 cm 3 g À1 at 1bar and 273 K). [16][17][18][19][20] Several porous frameworks containing nitrogen-rich functional groups,s uch as pyridine, amine, imidazole and acylamide, were shown to have ag reater affinity towards the storing of carbon dioxide (CO 2 ). [1][2][3][4][5] The main advantages of MOFs are considered to be their high surface areas, well defined pore sizes, exposed metal sites and high thermal stabilities.…”

van der Waals Epitaxial Growth of 2D Metal–Porphyrin Framework Derived Thin Films for Dye‐Sensitized Solar Cells

“…Thus, there is a huge interest in Pt-free materials for CE fabrication, such as inorganic semiconductors, [5] carbon materials, [6] conductive organic polymers, [7] and so on. [12,13] Recently, the tunable functionality of MOFs has allowed these porous materials as precursors or sacrificial templates for the preparation of electrode materials in DSSCs. [12,13] Recently, the tunable functionality of MOFs has allowed these porous materials as precursors or sacrificial templates for the preparation of electrode materials in DSSCs.…”