CrystEngComm Blog

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Biofuels, such as plant oils, are a potential alternative energy source. However, the presence of impurities like gums and phospholipids can hamper their use in diesel engines. Phospholipids (which are made up of a fatty acid, a simple organic group and a phosphate group) can be removed in the conventional refining process, but this causes loss of oil and nutrients and uses both water and chemicals.

A new paper shows how phospholipids can be efficiently removed using Y₂O₃ cubes and flowers, made hydrothermally, as shown in the figure below. Y₂O₃ is a Lewis acid and the positively charged metal atom attracts the negatively charged phospholipid, absorbing it onto the metal-oxide surface. Y₂O₃ flowers have a larger specific surface area than cubes, so absorb phopholipds more efficiently (approximately 90% rather than 80% of 870 ppm phospholipid in soyabean oil). This demonstrates that both flowers and cubes could have potential use in the separation of phospholipids from plant oils.

For more information see the paper at:

Hydrothermal synthesis of Lewis acid Y₂O₃ cubes and flowers for the removal of phospholipids from soybean oil
Yi-Feng Lin, Jhen-Huei Chen, Shih-Hong Hsu and Tsair-Wang Chung
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE40791H, Paper

Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors. Currently she works as a scientific database editor.

Posted on behalf of Josh Campbell, web writer for CrystEngComm 

Metal nanoparticles (NPs) are structures within the µm-nm range that exhibit amazing properties and morphologies. Photochemical and superparamagnetic effects have been reported while everything from nanostars to nanoreefs have been created. NPs are often thought to be a product of modern science but their use dates back hundreds of years, used in pottery finishes and for staining glass. Michael Faraday first described the effect of gold colloids on glass in 1857. NPs are usually prepared by physical or chemical methods, and each has its own advantages and problems. Physical methods such as vapour deposition and laser ablation do not offer complete control over the size of the NPs unless at extreme conditions. These typically require a solid substrate, limiting their use in producing liquid suspensions. Chemical methods involve the reduction of the metal ions dissolved in appropriate solvents and for noble metals have produced NPs down to micron level. However, this method does not work well for metals prone to oxidation.

This new paper describes the chemical synthesis of zinc nanoparticles which show exciting photoluminescence properties and a resistance to oxidation. ZnCl was dissolved in a phenylether and complexed with oleylamine before being reduced to Zn²⁺, after which it nucleates into the final structure. Hexagonal Zn particles form which have a diameter of 250-350nm and showed no oxide phases. The Zn particles also were found to emit light in the UV to blue range. The authors suggest that this is due to the 3d-Fermi gap being lowered compared to bulk zinc, and the sp band itself being discretized.

Find out more:

Chemical synthesis of blue-emitting metallic zinc nano-hexagons
Nguyen T. Mai, Trinh T. Thuy, Derrick M. Mott and Shinya Maenosono
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE40801A, Paper

 Josh Campbell is a PhD student currently at the University of Southampton studying crystal structure prediction of organic semiconductors. He received his BSc from the University of Bradford.

During the months April – June, the following articles are in the Top Ten most accessed:-

Hydrogen-bond network in isomeric phenylenedipropynoic acids and their DABCO salts. Water mediated helical hydrogen bond motifs 
Rajendran Saravanakumar, Babu Varghese and Sethuraman Sankararaman  
CrystEngComm, 2009,11, 337-346 
DOI: 10.1039/B816658G    
 
Chemoaffinity-mediated crystallization of Cu₂O: a reaction effect on crystal growth and anode property 
Kunfeng Chen and Dongfeng Xue   
CrystEngComm, 2013,15, 1739-1746 
DOI: 10.1039/C2CE26500A    

Five polyoxometalate-based inorganic–organic hybrid compounds constructed by a multidentate N-donor ligand: syntheses, structures, electrochemistry, and photocatalysis properties 
Zhe Zhang, Jin Yang, Ying-Ying Liu and Jian-Fang Ma 
CrystEngComm, 2013,15, 3843-3853 
DOI: 10.1039/C3CE40210J     

Hydrothermal syntheses, structures and luminescent properties of d10 metal–organic frameworks based on rigid 3,3′,5,5′-azobenzenetetracarboxylic acid polyoxometalate-based inorganic–organic hybrid compounds constructed by a multidentate N-donor ligand: syntheses, structures, electrochemistry, and photocatalysis properties 
Wenlong Liu, Lihu Ye,L infang Liu, Limin Yuan, Jiaxun Jiang and Chaoguo Yan   
CrystEngComm, 2008,10, 1395-1403 
DOI: 10.1039/B806360E     

Synthesis of uniform octahedral tungsten trioxide by RF induction thermal plasma and its application in gas sensing 
Haibao Zhang, Mingshui Yao, Liuyang Bai, Weicheng Xiang, Huacheng Jin, Jinlin Li and Fangli Yuan  
CrystEngComm, 2013,15, 1432-1438 
DOI: 10.1039/C2CE26514A     

Facile synthesis of Co₃O₄ by molten salt method and its Li-storage performance 
M. V. Reddy, Zhang Beichen,  K. P. Loh and B. V. R. Chowdari   
CrystEngComm, 2013,15, 3568-3574 
DOI: 10.1039/C3CE26985J     

Large-scale synthesis of porous Ni2P nanosheets for lithium secondary batteries 
Yi Lu, Jiang-ping Tu, Qin-qin Xiong, Heng Zhang, Chang-dong Gu, Xiu-li Wang and Scott X. Mao   
CrystEngComm, 2012,14, 8633-8641 
DOI: 10.1039/C2CE26378E     

Ionothermal synthesis and lithium storage performance of core/shell structured amorphous@crystalline Ni–P nanoparticles 
Heng Zhang, Yi Lu, Chang-Dong Gu, Xiu-Li Wangand Jiang-Ping Tu
CrystEngComm, 2012,14, 7942-7950 
DOI: 10.1039/C2CE25939G     

Crystal structures and growth mechanisms of octahedral and decahedral Au@Ag core-shell nanocrystals prepared by a two-step reduction method 
Masaharu Tsuji, Nozomi Nakamura, Masatoshi Ogino, Koji Ikedo and Mika Matsunaga  
CrystEngComm, 2012,14, 7639-7647 
DOI: 10.1039/C2CE25569C     

Synthesis of graphene–ZnO nanorod nanocomposites with improved photoactivity and anti-photocorrosion 
Zhang Chen, Nan Zhang and Yi-Jun Xu 
CrystEngComm, 2013,15, 3022-3030 
DOI: 10.1039/C3CE27021A     

Why not take a look at the articles today and blog your thoughts and comments below.

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Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Pigments are solid colourants used in the production of materials such as paints, inks and plastics. For a given pigment, the colour is affected by particle size and morphology, among other things. Formation of a multi-componet system (co-crystal) may also affect the colour and, additionally, may alter properties like heat stability. However, pigments tend to be insoluble in common solvents, rendering production of co-crystals by conventional, solution-based, methods difficult.

A new paper shows how mechanochemical co-crystallisation (ie grinding the components in a small quantity of solvent) can produce co-crystals of the pigment fluorescein (see diagram below) quickly and in quantitative yields. Co-crystals with three different co-formers were produced each with a different colour. Attempts to produce co-crystals using solvent-based methods were also successful, but produced different co-crystals and less efficiently. Authors discuss the broad implications of the results for the pigment and dye industries, suggesting mechanochemical co-crystallisation as an efficient route to colour- and property-tunable pigments.

More information can be found in the full paper at:

Advantages of mechanochemical cocrystallisation in the solid-state chemistry of pigments: colour-tuned fluorescein cocrystals
Dejan-Krešimir Bučar, Stefan Filip, Mihails Arhangelskis, Gareth O. Lloyd and William Jones
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41013G, Communication

Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors. Currently she works as a scientific database editor.

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Many important drug molecules are hydrophobic so methods to successfully introduce these into the body and make them bioavailable must be developed. Peptide-based molecules are an attractive delivery vehicle due to their biocompatibility, recognition properties, biodegradability and hydrophobic-hydrophilic balance.

A new paper shows how three gamma-peptides, with different degrees of flexibility, can self-assemble to form porous microspheres (see diagram below). The anticonvulsant drug carbamazepine has been encapsulated in these microspheres, which range in diameter from 300nm-1µm. The microspheres have limited water solubility, so there is a sustained release of the drug by dissolution of the microsphere. The authors suggest tailoring of the capsule properties could lead to controlled drug delivery and release.

Find out more in the paper:

Fabrication of microspheres from self-assembled γ-peptides
Suman Kumar Maity, Santu Bera, Arpita Paikar, Apurba Pramanik and Debasish Haldar

CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE40689J, Paper

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm 

The stability and other properties of compounds in the solid state are important considerations when considering their potential uses. Two strategies commonly followed to enhance desirable properties are to form co-crystals (crystals containing more than one type of neutral molecule) and to form salts (ionic crystals). In both cases, the new crystal forms generated have different properties than the parent compounds. For example, forming a salt of a drug molecule often improves its solubility, hence making it more bioavailable. Salts, however, often have problematic properties including deliquescence (i.e. absorbing water until they dissolve). 

A new paper shows how co-crystals can be formed between ionic and neutral forms of the same molecule (conjugate acid-bases, or CABs) which are more stable than the parent molecule. The molecules studied are benzoic acids, salts of which are used as preservatives in the food and pharmaceutical industry. However, they are hygroscopic and degrade in air. Formation of CAB co-crystals significantly improves their stability, particularly at high relative humidity (RH), as shown in the figure below. X-ray crystal structures of the CAB co-crystals show formation of strong short hydrogen bonds between the components. The authors postulate that this interaction is more favourable than the interaction with water, and is the root of the improved stability. 

Moisture sorption profiles of (a) sodium benzoate (mono salt), 3, sodium dihydrogen tris(benzoate) (CAB cocrystal), 4, and (b) potassium benzoate (mono salt), 5, and potassium hydrogen bis(benzoate) (CAB cocrystal), 6.

Find out more from the paper: 

Improved solid-state stability of salts by cocrystallization between conjugate acid–base pairs
Sathyanarayana Reddy Perumalla and Changquan Calvin Sun
CrystEngComm, 2013, DOI: 10.1039/C3CE40593A