CrystEngComm Blog

Metal–organic frameworks are materials containing coordination bonds between organic linkers and metal ions or clusters, exclusion of guest molecules in the structure can create a highly porous material with potential for gas storage, gas separation or catalysis. Other well studied nanoporous materials include zeolites, metal oxide molecular sieves, silica gels, activated carbons, covalent organic frameworks and organic network polymers.

This highlight from Jian Tian, Praveen K. Thallapally and B Peter McGrail from Pacific Northwest National Laboratory reviews a very different class of nanoporous material, those comprised entirely of discrete organic molecules containing only weak non-covalent interactions. Often there is very close packing in the crystals (with voids or channels rarely exceeding 25 Angstroms) but under the right conditions solvents can be included within the structure in zero, one, two or three dimensional solvent accessible voids.

If the solvent can be easily removed from the structure highly porous crystalline materials can be made  from organic compounds, the difficulty however is that upon desolvation the crystals often collapse into closely packed structures. This review discusses a wide range of structures which have been found to be stable as porous organic molecular materials, including crystalline structures with voids and amorphous solids with interconnected disordered pores. Read the CrystEngComm Hot Article (which is free to access for 4 weeks) for more details.

Porous organic molecular materials
Jian Tian, Praveen K. Thallapally and B Peter McGrail
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE06457J, Highlight

This comprehensive Highlight by Min Kim and Seth Cohen outlines the discovery, development and functionalization of Zr(IV)-based metal–organic frameworks. MOFs in general have been widely studied and the potential in biotechnological applications, catalysis, chemical sensing, gas separation and gas storage is of great interest.

Zr(IV)-based MOFs were discovered in 2008 and in that short period substantial research has been undertaken with more than forty functionalised Zr(IV)-based MOFs discovered. This review looks in detail at the synthesis, functionalization and application of this relatively new addition to the MOF family. The authors note the great potential for Zr(IV)-based MOFs, including applications in catalysis, photo-chemical reactions and molecular separations.

To find out more access this article free for the next 4 weeks

This article will be published later in the year in a CrystEngComm themed issue focussing on post-synthetic modification of coordination networks.

Discovery, development, and functionalization of Zr(IV)-based metal–organic frameworks
Min Kim and Seth M. Cohen
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE06491J, Highlight

Magnetism in organic crystal structures can be quite a complex property and understanding it’s subtleties is an intense field of study. This HOT Highlight in CrystEngComm details the magnetic properties and crystal structures of functionalized pyrene radicals, Paul M. Lahti et al. found that different polymorphs led to different magnetic properties and that intermolecular distances of NO—ON contacts played a key role in the resultant magnetism. The authors also discovered they could ‘shepherd’ molecules by adding hexafluorobenzene (HFB), altering the stacking and intermolecular contacts resulted in different exchange interactions between the radical molecules. In the co-crystal they observed a weaker but further extending magnetic behaviour, showing how rational manipulation of crystallisation conditions can lead to controlled magnetic properties.

Read the full Highlight which is free to access for 4 weeks in CrystEngComm

Radicals organized by disk shaped aromatics – polymorphism and co-crystals that tune inter-electron exchange
Handan Akpinar, Joel T. Mague, Miguel A. Novak, Jonathan R. Friedman and Paul M. Lahti
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C1CE06096A