Post-Synthetic Modification Unlocks a 2D-to-3D Switch in MOF Breathing Response: A Single-Crystal-Diffraction Mapping Study.

Post-synthetic modification (PSM) of the interpenetrated diamondoid metal-organic framework (Me NH )[In(BDC-NH ) ] (BDC-NH =aminobenzenedicarboxylate) SHF-61 proceeds quantitatively in a single-crystal-to-single-crystal manner to yield the acetamide derivative (Me NH )[In(BDC-NHC(O)Me) ] SHF-62. Continuous breathing behaviour during activation/desolvation is retained upon PSM, but pore closing now leads to ring-flipping to avert steric clash of amide methyl groups of the modified ligands. This triggers a reduction in the amplitude of the breathing deformation in the two dimensions associated with pore diameter, but a large increase in the third dimension associated with pore length.

Amino Acid Residues Determine the Response of Flexible Metal-Organic Frameworks to Guests.

Flexible metal-organic frameworks (MOFs) undergo structural transformations in response to physical and chemical stimuli. This is hard to control because of feedback between guest uptake and host structure change. We report a family of flexible MOFs based on derivatized amino acid linkers.

The Anisotropic Responses of a Flexible Metal-Organic Framework Constructed from Asymmetric Flexible Linkers and Heptanuclear Zinc Carboxylate Secondary Building Units.

A new porous and flexible metal-organic framework (MOF) has been synthesized from the flexible asymmetric linker -(4-carboxyphenyl)succinamate (CSA) and heptanuclear zinc oxo-clusters of formula [ZnO(carboxylate)DMF] involving two coordinated terminal DMF ligands. The structural response of this MOF to the removal or exchange of its guest molecules has been probed using a combination of experimental and computational approaches. The topology of the material, involving double linker connections in the and directions and single linker connections along the axis, is shown to be key in the material's anisotropic response.

Chemical control of structure and guest uptake by a conformationally mobile porous material.

Metal-organic frameworks (MOFs) are crystalline synthetic porous materials formed by binding organic linkers to metal nodes: they can be either rigid or flexible. Zeolites and rigid MOFs have widespread applications in sorption, separation and catalysis that arise from their ability to control the arrangement and chemistry of guest molecules in their pores via the shape and functionality of their internal surface, defined by their chemistry and structure. Their structures correspond to an energy landscape with a single, albeit highly functional, energy minimum.

Hydrogen bonding halogen bonding: the solvent decides.

Control of intermolecular interactions is integral to harnessing self-assembly in nature. Here we demonstrate that control of the competition between hydrogen bonds and halogen bonds, the two most highly studied directional intermolecular interactions, can be exerted by choice of solvent (polarity) to direct the self-assembly of co-crystals. Competitive co-crystal formation has been investigated for three pairs of hydrogen bond and halogen bond donors, which can compete for a common acceptor group.

Crystallographic studies of gas sorption in metal-organic frameworks.

Metal-organic frameworks (MOFs) are a class of porous crystalline materials of modular design. One of the primary applications of these materials is in the adsorption and separation of gases, with potential benefits to the energy, transport and medical sectors. In situ crystallography of MOFs under gas atmospheres has enabled the behaviour of the frameworks under gas loading to be investigated and has established the precise location of adsorbed gas molecules in a significant number of MOFs.