Archive for July, 2012

Understanding hydrogen bonding

Co-crystallisation is an important tool for establishing the importance of intermolecular interactions in the solid state. One strategy adopted by Christer Aakeröy and his team at Kansas State University is to examine whether crystallisation of two molecules results in a homomeric interaction (essentially recrystallisation) or a heteromeric interaction (co-crystallisation). Combining 2-aminopyrazine derivatives with numerous carboxylic acids, the team discovered that they could attribute the success of co-crystallisation with electrostatic charges on the hydrogen bond acceptor sites – as they predicted, the lower the charge, the lower the supramolecular yield of the reaction.

co-crystallisation vs recrystallisation

Although hydrogen bonding is a fundamental concept taught to us in the classroom, we still have a lot to learn!

Read the article to find out more…

Exploring the structural landscape of 2-aminopyrazines via co-crystallizations
Christer B. Aakeröy, Prashant D. Chopade, Claudia Ganser, Arbin Rajbanshi and John Desper

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Highlights from themed issues on ionic liquids

                

The field of ionic liquids has seen phenomenal growth in recent years, with the topic spanning a variety of disciplines across the chemical sciences. The recent themed issues from ChemComm, PCCP and CrystEngComm showcase some of the latest developments from a range of scientific subjects utilising the unique properties of ionic liquids.

Highlights from these themed issues include the articles below, which are free to download until the 24th August. You can also access the full themed issues by clicking on the buttons above.

  Click here to access the full list of articles

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Porous aromatic frameworks

Teng Ben and Shilun Qiu discuss porous aromatic framework network formation and the relationship between secondary building units and function in this hot Highlight article.  The ability to control the pore size in porous aromatic frameworks lends itself to numerous applications, including in molecular separation, catalysis, photoelectric materials, clean energy and carbon dioxide capture and storage.

You can download the full article below, which is free to access for 4 weeks.

Porous aromatic frameworks: Synthesis, structure and functions
Teng Ben and Shilun Qiu
CrystEngComm, 2012
DOI: 10.1039/C2CE25409C, Highlight

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Hydrogels for studying biomineralisation

Hydrogel-based double-diffusion systems for studying biomineralization

Hydrogel-based double-diffusion systems for studying biomineralization

This Highlight presents an overview of hydrogel-based double-diffusion systems to study biomineralization.  The authors describe two types of diffusion systems: static and dynamic.  They evaluated four such systems to design  an optimized system taking into account the type of hydrogel, the boundary conditions and design strategy.

Gels represent a good model to study and understand biomineralization because the mineral deposition that occurs in many mineralization processes  in vivo takes place in gelling environments; however,  they are not often used due to their complexity and poor knowledge of ionic diffusion.

Read more about biomineralisation for FREE at:

Rediscovering hydrogel-based double-diffusion systems for studying biomineralization
Jason R. Dorvee , Adele L. Boskey and Lara A. Estroff
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE25289A

Other articles by Lara A. Estroff and co-workers which may also be of interest are:

Gel incorporation inside of organic single crystals grown in agarose hydrogels
Hanying Li, Yuzo Fujiki, Kazuki Sada and Lara A. Estroff
CrystEngComm, 2011, 13, 1060-1062
DOI: 10.1039/C0CE00118J, Communication

Porous calcite single crystals grown from a hydrogel medium
Hanying Li and Lara A. Estroff
CrystEngComm, 2007, 9, 1153-1155
DOI: 10.1039/B709068D, Communication
From themed issue: CrystEngComm focuses on biomineralisation

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Facile, economical and magnetically recoverable photo-Fenton’s reagent

Zhijun Luo, Xiangyang Wu et al. have recently developed a facile one-step route to generate magnetite/carboxylate-rich carbon spheres exhibiting excellent photodegradation properties, without the need of H2O2 or UV light.

Wastewater can contain many contaminants including a wide range of organic material; the photo-Fenton reaction is a highly efficient way to oxidise these pollutants using Fe3+, H2O2 and UV light to generate .OH radicals.

The materials reported here are highly water-dispersible, easy to make and operate under visible light across a wide pH range. The magnetite/carboxylate-rich carbon spheres can also be recovered magnetically making this a convenient reaction to use.

A schematic illustration of the magnetite/carboxylate-rich carbon spheres (MCRCS) generating hydroxyl radicals under visible light in water.

 

You can take a look at how the particles particles behave under applied magnetic fields in these videos, pure nano magnetite in water and magnetite/carboxylate-rich carbon spheres in water.

You can also download the full communication, which is free to access for 4 weeks
A visible-light-driven solid state photo-Fenton reagent based on magnetite/carboxylate-rich carbon spheres
Zhijun Luo, Hongjun Tang, Lingling Qu, Tingting Han and Xiangyang Wu

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July Crystal Clear: Crystal Cavern

An image taken through an optical microscope of L-arginine acetate grown using a 'Metal-Assisted and Microwave-Accelerated Evaporative Crystallization’ process.

The beautiful image in this month’s crystal clear isn’t actually a crystal cavern. It is crystals of L-arginine acetate grown using a new crystallisation technique. The crystals are of particular interest in non-linear optics given their second harmonic generation properties.

The Aslan Research Group have developed a new crystallisation method to grow L-arginine acetate crystals much faster than the previously reported cooling/evaporation method. The Metal-Assisted and Microwave-Accelerated Evaporative Crystallization process uses silver island films and low power microwave heating to grow the crystals quickly. The team also investigated functionalising the metal nucleation surface to see if this enhanced crystal growth. 

The image shown here is of the crystals created using bare silver island films and microwaves, the rest of the teams results, including full details of their growth process can be found in Issue 14 of CrystEngComm

Rapid crystallization of L-arginine acetate on engineered surfaces using metal-assisted and microwave-accelerated evaporative crystallization
Melissa A. Pinard, Tsehai A. J. Grell, Danielle Pettis, Muzaffer Mohammed and Kadir Aslan

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This months CrystEngSelects

Here is this month’s selection of Advance Articles and Accepted Manuscripts of interest to crystal engineers across RSC Journals

Articles are chosen from:
ChemComm,
Chemical Science,
CrystEngComm,
Dalton Transactions,
Journal of Materials Chemistry,
Nanoscale,
New Journal of Chemistry,
RSC Advances.

CLick here to expand the full list

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Competing cocrystals: Hydrogen-bonding vs. Halogen-bonding

Tomislav Friscic and colleagues report a cocrystal system that bonds by either hydrogen or halogen bonding depending on the stoichiometric ratio of the two components of the crystal. Interactions within crystal structures such as hydrogen bonding, ionic bonds, van der Waals forces and pi-interactions determine a material’s structure and properties.

Stoichiometric ratio of methyldiphenylphosphine oxide and p-diiodotetrafluorobenzene determines whether the resulting cocrystal will display hydrogen or halogen bonds

Understanding these interactions and engineering crystals with specific structures is important, the ability to switch the  interaction between hydrogen and halogen bonds by altering the ratio of molecules is an interesting discovery and helps establish the role halogen bonds play in molecular self-assembly.

Switching between halogen- and hydrogen-bonding in stoichiometric variations of a cocrystal of a phosphine oxide
Se Ye Oh, Christopher W. Nickels, Felipe Garcia, William Jones and Tomislav Friščić

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Advisory Board Member Lee Cronin wins Corday Morgan Prize

Lee Cronin is the Gardiner Professor of Chemistry at the School of Chemistry, University of Glasgow and on the Advisory Board of CrystEngComm.

The RSC recognises outstanding members of the chemical science community through its wide range of awards, you can see the full list of RSC 2012 winners here.

Lee is recognized for his creative studies in the field of inorganic chemistry, specifically the self-assembly and self-organization of inorganic molecules and the engineering of complex systems leading to the emergence of system-level behaviours.

His award citation is for “his outstanding work on the self-assembly of inorganic molecules and the engineering of complex systems”. Congratulations Lee from all at CrystEngComm!

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CrystEngComm impact factor released!

CrystEngCommThe 2011 Journal Citation Reports ® (Thomson Reuters, 2012) have been released and CrystEngComm has received a 5 year impact factor* of 4.02 and an Immediacy Index** of 0.844, the highest Immediacy Index for any crystal engineering journal!

We would like to thank all our authors, readers and referees who have contributed towards this success. Our thanks also go to our Editorial and Advisory Board Members and our Associate Editors for all their hard work and dedication to the journal.

A full list of RSC successes can be found at the RSC Impact Factor release.

For more information about CrystEngComm, including how to submit your research, check out the journal homepage.

*A 5-year impact factor is the average number of times articles from a journal published in the past five years have been cited in the JCR year. It is calculated by taking the number of citations in the JCR year to articles published in the preceding 5 years and dividing by the number of articles published in the previous 5 years.

** The Immediacy Index is a measure of how topical and urgent work published in a scientific journal is. It is measured by dividing the number of citations made to articles in a journal in a given year by the number of citeable articles published in the journal for the same year.

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