CrystEngComm Blog

Posted on behalf of Josh Campbell, web writer for CrystEngComm

Lithium ion batteries (LIB) are ubiquitous in modern life. Consumer electronics generally use LIBs based on LiCoO2 but these have safety drawbacks and environmental concerns. NiO has been proposed as a replacement material for the anode due to its safety, low cost and theoretical capacity. However bulk NiO has poor electrochemical performance and much research has been focused on developing nanostructures that would allow NiO to reach its full potential. Porous hollow materials can offer many improvements compared to the bulk such as improved capacity and cycling performance.

A new paper presents the synthesis of NiO porous hollow microspheres using L-cysteine as a directing agent. The directing agent causes the spheres to form, as without it the precursors to NiO grow into nanoplate-assembled flowers. The authors propose a mechanism for the sphere formation: L-cysteine complexes with Ni(OH)2, which during hydrothermal treatment aggregate due to the hydrophobic interactions of the L-cysteine. These continue to aggregate throughout treatment and assemble into spheres. The NiO microspheres showed improved reversibility and good capacity retention. The authors attribute the improved performance to the hollow architecture which allows for fast ion/electron transfer.

Find out more from the paper:

L-cysteine-assisted preparation of porous NiO hollow microspheres with enhanced performance for lithium storage
Dong Xie, Qingmei Su, Zimin Dong, Jun Zhang and Gaohui Du
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41161C, 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.

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Non-linear optical (NLO) materials are in demand due to their potential applications in photonic technologies such as laser frequency conversion and signal communication. Chiral coordination networks are likely to have good NLO properties but their formation from achiral building blocks (tectons) can be difficult.

A new paper presents a systematic study of Cd-complexes containing a range of related tetrazolate tectons, with different substituents, allowing the importance of steric and electronic factors to be considered. One molecular structure and three framework structures were formed. The size of the substituent is significant here, with smaller substituents favouring the formation of network structures. In these network structures, which crystallise in chiral space groups, the framework where the tecton has the strongest electron withdrawing substituent shows the highest second harmonic generation SHG efficiency. This compound is also phasematchable, a characteristic necessary for a laser frequency conversion material.

For more information see the paper at:

From achiral tetrazolate-based tectons to chiral coordination networks: effects of substituents on the structures and NLO properties
Jian-Zhen Liao, Da-Chi Chen, Fang Li, Yong Chen, Nai-Feng Zhuang, Mei-Jin Lin and Chang-Cang Huang
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41037D, 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

Ditopic ligands (ligands capable of coordination at two separate sites) allow the creation of well-ordered extended complexes containing different cations. They are usually N-, P-, O-, and S-containing (or in their N, O-, N, S,- and N, P-combinations) organic molecules, and have been used in various applications such as monitoring guest exchange and the creation of metal organic frameworks. The multi-centre nature of these ligands allows for other interactions outside of coordinative and hydrogen bonding such as halogen bonding. 3-(4-pyridyl)-2,4-pentanedione (HacacPy) is a well known ditopic ligand, and in this new work, has been used to create a crystal in which these three types of bonding are represented.

Three complexes containing HacacPy and tetrafluorodiiodobenzene (TFDIB) were prepared. Compound 1 showed the halogen bonding produced between the pyridine N and the iodine of TFDIB with this being the only coordination centre used. In compound 2 HacacPy is deprotonated and is involved in coordinative bonding using the acac part of the ligand and two pyridine N atoms form halogen bonds to TFDIB producing chains. Compound 3 introduces a third interaction, hydrogen bonding of a Py N to a solvent molecule which is in turn halogen bonded to a TDIB which is halogen bonded to another Py N. The authors analysed the charge density of 3 and provided the first tentative experimental results of the effect of metal coordination on halogen bonds.

Find out more from the paper:

3-(4-Pyridyl)-2,4-pentanedione – a bridge between coordinative, halogen, and hydrogen bonds
Carina Merkens, Fangfang Pan and Ulli Englert
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41306C, 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.

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Tungsten oxide hydrates (like WO₃•nH₂O, n=0-2) show promising photocatalytic properties. They efficiently oxidise a range of organic compounds including textile dyes and bacterial pollutants when irradiated with blue light and also have potential use in the treatment of acid polluted solutions. An understanding of the structure dependent nature of the activities is required to fully develop them and new preparation methods can facilitate this. Microwave heating methods are attractive as they increase reaction rates and improve the yields and purity of products.

This new paper shows how microwave assisted synthesis of WO₃•0.33H₂O can efficiently produce orthorhombic crystallites. The products of syntheses with and without microwave heating via three different methods were compared. In each case, different particle sizes and morphologies were formed. For each of the pairs (with or without microwave heating), the photocatalytic properties were enhanced for the products of the microwave-assisted synthesis. Authors suggest this is due to the preferential growth along the (100) face exposing more of the highly acidic (010) faces.

For more details see the paper at:

Microwave-assisted growth of WO₃·0.33H₂O micro/nanostructures with enhanced visible light photocatalytic properties
Jiayin Li, Jianfeng Huang, Jianpeng Wu, Liyun Cao, Qijia Li and Kazumichi Yanagisawa
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41005F, 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

Quantum dots combine nanocrystals and semiconductors to create materials small enough to show quantum mechanical properties. The excitons (a bound state of an electron and an electron hole) are squeezed together, and if this confinement is in three dimensions, a quantum dot is formed; for two dimensions, a quantum wire,  and in one dimension, a quantum well. This squeezing together results in the bandgap of the material becoming highly size dependent, thus tunable and usually blue-shifted. Chalcogenide materials have always drawn research in semiconducting materials, with ternary and quarternary alloys offering even more control over the bandgap while also improving stability or size selectivity.

This new paper shows the synthesis of AgBiS₂ monodispersed quantum dots that show an extremely high dielectric constant. They were synthesized via the hot injection method, with an average diameter of 8.5nm ± 1.2nm, and the optical band gap energy measured confirmed that strong quantum confinement was taking place. Due to the small size of the nanoparticles, grain boundary effects were expected to dominate the electronic properties. The dielectric constant of the pellets is on the order of 105 and the authors confirmed grain boundaries with large resistances and capacitances gave rise to the huge dielectric constant which has significant implications in the design of similar materials.

Read the paper to find out more:

The synthesis of monodispersed AgBiS₂ quantum dots with a giant dielectric constant
Chao Chen, Xiaodong Qiu, Shulin Ji, Chong Jia and Changhui Ye

CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41304G, Communication

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.

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Porous metal-organic frameworks (MOFs) have potential applications ranging from gas storage to chemical sensing. To fully realise these, the ability to cast into a given form, such as a thin film, is important. Nanometre (nm) sized particles are an attractive target, potentially allowing properties to be fine-tuned precisely. Formation of MOF nanoparticles has previously been achieved but obtaining sizes below 100nm is difficult and can lack reproducibility.

A new paper shows how the MOFs HKUST-1 and IRMOF-3 can be produced using additive-mediated syntheses. These involve mixing a polymer (for the synthesis of HKUST-1) or polymer-surfactant combination (for IRMOF-3) with the metal and ligand sources. This produces nanoparticles of the MOF between 30nm and 300nm, depending on the reaction temperature, reaction time and the quantities of additives used. The synergy of the polymer and surfactant gives the best control over size and monodispersity, i.e. the particles produced are within a narrow size range. This method could potentially be useful in producing MOFs for drug delivery or sensing where ultra-small particles or films are required.

For more information see the full paper:

Additive-mediated size control of MOF nanoparticles
Annekathrin Ranft, Sophia B. Betzler, Frederik Haase and Bettina V. Lotsch

CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41152D, Communication

Gwenda KydGwenda 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

Rare earth metals and their compounds are some of the most important elements in modern economies and science. They can be found in superconductors, catalytic converters and lasers. Most rare earth ions also show the phenomenon of upconversion (UC). UC is the emission of light at shorter wavelengths than initially absorbed at for example the conversion of infrared to visible light. UC effects show great promise in the bioimaging field, providing narrow emission bandwidths and high-signal to noise ratio due to being able to use near infra-red sources of excitation. Rare earth halides are known to increase UC luminescence but chlorides and bromides are usually sensitive to moisture and not suitable for labelling biomolecules.

A new highlight shows the most popular way of synthesizing rare earth fluorides and their applications as luminescent labels. Thermal decomposition is the most common synthesis method and gives nanocrystals with well-defined shapes and good size selectivity. However there are drawbacks (such as the strict experimental conditions) which have led to the development of coprecipitation and microwave assisted methods among others. These nanoparticles with UC properties have also recently shown promise being used as multimodal imagers. Multimodal imaging uses more than one technique and work is being done to integrate magnetic components into UC nanocrystals to combine MRI and luminescent imaging.

Find out more from the article:

Rare earth fluorides upconversion nanophosphors: from synthesis to applications in bioimaging
Song Wang, Jing Feng, Shuyan Song and Hongjie Zhang
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE40679B, Highlight

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.

Posted on behalf of Gwenda Kyd, web writer for CrystEngComm

Metal-organic frameworks (MOFs) are porous networks with a wide range of potential applications including gas storage and sensing. For their potential to be fully realised in integrated systems, efficient methods of producing thin films and patterns are crucial. Although methods exist for MOFs, these are are less developed than for other materials such as ZnO.

A new paper shows how thin films or patterns of the MOF ZIF-8 can be produced by melting the required ligand, 2-methylimidazole , in contact with a ZnO film or pattern. If the process is carried out under vacuum with an excess of ligand, it is totally solvent- and waste-free. Using this method with ZnO supported films and patterns is demonstrated to replicate the morphologies in the resulting ZIF-8, as shown in the diagram below. ZIF-8 is highly stable and has many possible uses including molecular separation and as an insulator in microelectronics. The reported strategy could allow new applications for ZIF-8 films to be developed.

For more information see the paper at:

Solvent-free synthesis of supported ZIF-8 films and patterns through transformation of deposited zinc oxide precursors
Ivo Stassen, Nicolò Campagnol, Jan Fransaer, Philippe Vereecken, Dirk De Vos and Rob Ameloot
CrystEngComm, 2013, Advance Article
DOI: 10.1039/C3CE41025K, Communication

Gwenda KydGwenda 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.

Over time, gleaming teeth become stained by repeated exposure to vices such as coffee, red wine or cigarettes. Current whitening methods include replacing the crown of the tooth or etching off stained enamel using chemical abrasives like hydrogen peroxide. These require the removal of part of a healthy tooth, and can lead to gum irritation and sensitive teeth.

Fluorapatite, polyethylene oxide and a polymer derived from the neurotoxin acrylamide have been combined by Chinese scientists to make a film that can restore teeth to their natural colour.

Read the full story at Chemistry World

PEO-assisted precipitation of human enamel-like fluorapatite films for tooth whitening
Shize Liu, Yujing Yin and Haifeng Chen

CrystEngComm, 2013,15, 5853-5859
DOI: 10.1039/C3CE40388B, Paper

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.