This tutorial review summarises recent advances in the direct supramolecular templating of metal-organic frameworks (MOFs) with hierarchical porosity across the micro- and mesoporous regimes. These are set against the important synthetic considerations that need to be addressed to ensure that strong interactions between the MOF precursors and a stable template assembly allow the highest chance of success. The article is grouped by template type and each category is illustrated with key examples and, where reported, an evaluation of their enhanced properties arising from the hierarchical structuring of the porous networks.

Highly porous magnetic MOF microreactors can be prepared around a Pickering-stabilized hydrogel core, providing a facile means for the encapsulation of enzymes for size-selective biocatalysis.

The addition of guanidinium-based surfactants to the synthesis of HKUST-1 reveals a novel surface patterning effect where meso-and macroscopic features appear on the MOF crystals. The size of the features increases with increasing alkyl chain length of the guanidinium amphiphiles, and their formation is strongly dependent on the presence of water which appears to more favourably etch the crystal surfaces when the surfactants are employed. The patterned crystals display intermediate type I/IV isotherms and the presence of the surface features have been evaluated for the chromatographic separation of styrene and ethylbenzene. Some degree of control over the interactions between the framework building blocks and the amphiphiles is afforded, and by simply changing the order of addition of the reactants the guanidinium surfactants promote the formation of HKUST-1 nanoparticles.

a Metal oxides can be used as hard sacrificial templates for the preparation of multifunctional core-shell MOF-based composites following reaction with the organic linker. This is a facile method, but often structures of well-defined shape are only obtained under narrow ranges of conditions, the shape can be lost completely and low levels of MOF conversion observed. Using the prototypical framework ZIF-8 we present an alternative surfactant-assisted surface passivation strategy where the ZnO precursor particles are first coated with a guanidinium-based amphiphile. The surfactant interacts strongly with the oxide surface and allows fine-tuning of the release of Zn(II) and ZIF-8 nucleation by the level of surface coverage permitting a range of well-defined ZnO@ZIF-8 core-shell architectures to be prepared including in water. Further, selective base-etching of the oxide core provides facile access to hollow ZIF-8 and yolk-shell structures. We also demonstrate enhanced dye adsorption and recovery from aqueous mixtures using ZnO@ZIF-8 composite microspheres..

Open-shell π-conjugated compounds have recently received intense attention due to their unique properties and promising applications in materials science. However, the experiments on how the substituents affect their chemical bonding and structural motif remain less addressed. In this work, a series of tetrabenzo-Chichibabin's hydrocarbon (TBC) derivatives substituted by different electron-donating or -withdrawing groups at the termini were synthesized. The substituent effect was studied via X-ray crystallographic analysis. The strong electron-donating dimethylamino-group substituted TBC derivative underwent simultaneous oxidation to give two cyanine-like moieties at the termini. More interestingly, it exhibited unusual thermochromic and thermomagnetic behaviours.

Three new metal-organic frameworks (MOFs) are formed from the reaction of zinc with 5-hydroxyisophthalic acid (H 3 -5-hip) with a range of additives in dimethylformamide (DMF). The additives include water, pyridine, and [Me n NH 4−n ]Cl (n = 0−4) and, through hydrogen bonding, have a marked effect on the formation and phase of any resultant MOF, often in a narrow range of sub-stoichiometric concentrations. The three MOFs, [Me 2 NH 2 ][Zn 2 (5-hip)(H-5-hip)(H 2 O)].3.25DMF (1), α-[Me 2 NH 2 ] 2 [Zn 2 (5-hip) 2 ]·2DMF (2) and [Me 2 NH 2 ][Me 4 N] 2 [Zn 4 (5-hip) 2 (H-5-hip 2.5 )]·3DMF (3) have solvent-accessible pores and the flexibility of the MOFs allows relaxation from a porous state to minimise the void space on desolvation. Topological analysis of the frameworks reveals two previously unrecorded MOF topologies. Compounds 2 and 3 are fluorescent while this property is absent in compound 1. We also present a revised structure for the closely-related β-[Me 2 NH 2 ] 2 [Zn 2 (5-hip) 2 ]·2DMF (4).

Review: recent advances in the soft templating of metal—organic frameworks with hierarchical porosity across the micro‐ and mesoporous regimes; 50 refs.