Archive for the ‘Highlights’ Category

Hot Highlight: Porous organic molecular materials

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

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HOT Highlight: Zr(IV)-based metal–organic frameworks

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

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Herding? You’ll need either a dog, a pig, or HFB

 

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

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Predicting Perovskite

The 2H-perovskite related oxides are an interesting variant of the ABO3 perovskite structure family, however understanding which cation ratios produce which products isn’t always a straightforward task. Hans-Conrad zur Loye and team have compiled an extensive review of this remarkable structure family, compiling a database of recently synthesised compositions that have different cation ratios. By looking at the compositions and structures of these compounds the team have developed a simple method to predict new compositions, an indispensible tool for the synthetic chemist!

Read the full Highlight in CrystEngComm for free.

2H-perovskite related oxides: Synthesis, structures, and predictions
Hans-Conrad zur Loye, Qingbiao Zhao, Daniel E. Bugaris and W. Michael Chance
CrystEngComm, 2011, Highlight, DOI: 10.1039/c1ce05788j

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Highlight article: Colin Seaton reviews carboxylic acid co-crystals

In this CrystEngComm Highlight article Colin Seaton from the University of Manchester looks at the crystal engineering of co-crystals between carboxylic acids. Seaton looks at how Hammett substitution constants can help in the design and creation of multi-component crystalline materials.

Read the full review article to find out more…

Creating carboxylic acid co-crystals: The application of Hammett substitution constants
Colin C. Seaton
CrystEngComm, 2011, DOI: 10.1039/C1CE05645J

To find out more about about Dr Seaton’s research read his recent CrystEngComm paper:

Epitaxial growth of polymorphic systems: The case of sulfathiazole
CrystEngComm, 2011, DOI: 10.1039/C1CE05585B

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Highlight: MOFs go green

Acetylene is an important starting material in the petrochemical and electronic industry for various industrial and consumer products, and a promising alternative energy source for future acetylene fuel cell vehicles. With the importance of acetylene, as a green fuel, this CrystEngComm Highlight, focuses on the storage of acetylene and its separation from the CO2, CH4, or C2H4 mixtures on micro-porous metal–organic frameworks (MOFs).

Read more for FREE at:

Microporous metal–organic frameworks for acetylene storage and separation
Zhangjing Zhang, Shengchang Xiang and Banglin Chen
CrystEngComm, 2011, Advance Article
DOI: 10.1039/C1CE05437F

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Lanthanide MOFs: Amazing Structures say ‘Hello!’ to Outstanding Properties

Ángeles Monge and co-workers delve into the world of Y and Sc MOFs in their recently published CrystEngComm Highlight article. You can read their HOT article for FREE until the 20th May 2011 by clicking on the following link:

Lanthanide, Y and Sc MOFs: where amazing crystal structures meet outstanding material properties
Ángeles Monge, Felipe Gándara, Enrique Gutiérrez-Puebla and Natalia Snejko
CrystEngComm, 2011, DOI: 10.1039/C0CE00891E

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Recent advances in anion–pi interactions

Over the past 10 years, anion–pi interaction has been recognized as an important weak force
that may occur between anionic systems and electron-deficient aromatics. Lately, this
supramolecular contact has experienced a rapidly growing interest. The following Hot article by Patrick Gamez and co-workers highlights the tremendous progress achieved in the field by emphasizing three important studies involving anion–pi interactions published in 2010.

Hot article FREE to read until 16th March 2011!

Recent advances in anion–π interactions
Arturo Robertazzi, Florian Krull, Ernst-Walter Knapp and Patrick Gamez
CrystEngComm, 2011, Advance Article DOI: 10.1039/C0CE00819B, Highlight

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Highlight: Organic fluorine in crystal engineering

Fluorine is special. It is uniquely characterized by its high electronegativity, relatively small size, very low
polarizability of the bound three nonbonding electron pairs and excellent overlap between fluorine 2s and 2p orbitals with corresponding orbitals of second row elements. In this CrystEngComm Highlight Deepak Chopra and Tayur Guru Row look at how the special attibutes of Fluorine affect the crystal lattice building of organic fluorine compounds.

Role of organic fluorine in crystal engineering
Deepak Chopra and Tayur N. Guru Row
CrystEngComm, 2011, DOI: 10.1039/C0CE00538J, Highlight

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Highlight: Controlling flexibility in crystal engineering

Here, Christopher Pigge (University of Iowa, US) discusses both the advantages and disadvantages that can arise when using flexible components in crystal engineering.  Both organic (mainly triaroylbenzenes) and metal-organic framework systems derived from flexible ligands are reviewed.

Read the Highlight by Christopher Pigge here.

Losing control? “Design” of crystalline organic and metal-organic networks using conformationally flexible buidling blocks
F. Christopher Pigge
CrystEngComm, 2011, Advance Article, DOI: 10.1039/c0ce00417k

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