Archive for the ‘News’ Category

Use of a MOP in the production of vanillin

A new method of producing vanillin (3-methoxy-4-hydroxybenzaldehyde) from ferulic acid using a catalytic MOP has been reported.

Vanillin, one of the main chemical components of vanilla, is an important flavouring agent in the food, cosmetic and other industries.  However, although it can be extracted from vanilla pods, less than 1% of the required quantity is obtained in this way.  The remainder is obtained by chemical synthesis using strong oxidising agents and toxic solvents.  Biotechnological production is also possible but there are problems with time-scale, purification and the nature of the bacteria used.   There is, therefore, a demand for cleaner, greener methods of production of vanillin.

This paper reports the production of vanillin in 60% yield from ferulic acid and hydrogen peroxide, when a MOP (metal-organic polyhedron) is used as a catalyst.  Like MOFs (metal-organic frameworks), MOPs are constructed from metal ions and organic ligands but rather than forming frameworks, MOPs are discrete polyhedra. MOFs have been widely studied as potential catalysts but MOPs are practically untried.  Reasons for this include their relative lack of stability and tendency to aggregate.   This paper uses the MOP formed from copper(II) and a ligand from 9H-carbazole-3,6-dicarboxylic acid.  There are also coordinated dimethylformamide and water molecules in the structure.

The catalyst is activated by removing the coordinated solvent molecules by heating.  Ferulic acid and hydrogen peroxide are then reacted in the presence of the MOP.  Best results are obtained when the reaction mixture is sonicated (to reduce possible aggregation of MOP molecules).  A mechanism is proposed starting with coordination of peroxide to the active Cu(II) coordination site (schematically shown above).

The recovered catalyst exhibits a loss of crystallinity and after 5 cycles activity shows a decline.  However, the paper demonstrates the potential for the catalytic use of MOPs for the simple production of vanillin and other compounds.

For more details, read the full paper here:

Synthesis of vanillin via a catalytically active Cu(II)-metal organic polyhedron

Elí Sánchez-González, Alfredo López-Olvera, Olivia Monroy, Julia Aguilar-Pliego, J. Gabriel Flores, Alejandro Islas-Jácome, Mónica A. Rincón-Guevara, Eduardo González-Zamora, Braulio Rodríguez-Molina and Ilich A. Ibarra  
CrystEngComm, 2017, Advance Article
DOI: 10.1039/C6CE02621D, Communication
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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. She published a book, ‘Molecules, Medicines and Mischief’, in 2014, on some of the chemicals found in plants and is currently working on a follow-up.

 

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Outstanding Reviewers for CrystEngComm in 2016

Following the success of Peer Review Week in September 2016 (dedicated to reviewer recognition) during which we published a list of our top reviewers, we are delighted to announce that we will continue to recognise the contribution that our reviewers make to the journal by announcing our Outstanding Reviewers each year.

We would like to highlight the Outstanding Reviewers for CrystEngComm in 2016, as selected by the editorial team, for their significant contribution to the journal. The reviewers have been chosen based on the number, timeliness and quality of the reports completed over the last 12 months.

We would like to say a big thank you to those individuals listed here as well as to all of the reviewers that have supported the journal. Each Outstanding Reviewer will receive a certificate to give recognition for their significant contribution.

Professor Dino Aquilano, University of Torino
Dr Timur Atabaev, Seoul National University
Dr Ian Dance, Unversity of New South Wales
Dr Laszlo Fabian, University of East Anglia
Professor Huiging Fan, Northwestern Polytechnical University
Dr Goutam Kole, SRM University
Dr Mahesh Kumar, Indian Institute of Technology Jodhpur
Dr Zheng Ren, University of Connecticut
Dr Dongpeng Yan, Beijing Normal University
Dr Jiatao Zhang, Beijing Institute of Technology

We would also like to thank the CrystEngComm board and the Inorganic community for their continued support of the journal, as authors, reviewers and readers.

If you would like to become a reviewer for our journal, just email us with details of your research interests and an up-to-date CV or résumé.  You can find more details in our author and reviewer resource centre

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Welcoming new Editorial board member: Professor Tong-Bu Lu

Welcome to CrystEngComm’s newest Editorial board member – Professor Tong-Bu Lu. Professor Lu works at the Institute for New Energy Materials and Low Carbon Technologies, based at the Tianjin University of Technology, China.

His research interests include the recognition and activation of molecules and ions by the macrocyclic compounds; the constructions of porous metal-organic frameworks, and investigation of their properties for gases storages and separation, ions exchange and chiral separation and pharmaceutical polymorphs and cocrystals. He has been recognised as a distinguished Professor in Guangdong Province, China

Please see below a selection of recent articles published by Professor Lu for CrystEngComm:

Interpenetrating metal–organic frameworks
Yun-Nan Gong, Di-Chang Zhong and Tong-Bu Lu
CrystEngComm, 2016, 18, 2596-2606
DOI: 10.1039/C6CE00371K, Highlight

Synthesis and structures of dinuclear cryptates with Zn(II), Cd(II) and Hg(II): tuning the cascade binding mode with metal ions
Feng Yan, Xiao-Mei Zhuang and Tong-Bu Lu
CrystEngComm, 2015, 17, 5832-5840
DOI: 10.1039/C5CE00817D, Paper

Thermodynamics and preliminary pharmaceutical characterization of a melatonin–pimelic acid cocrystal prepared by a melt crystallization method
Yan Yan, Jia-Mei Chen and Tong-Bu Lu
CrystEngComm, 2015, 17, 612-620
DOI: 10.1039/C4CE01921K, Paper

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Stability of the anti-histamine drug loratadine

Drugs are often prepared in crystalline form.  However, the relative thermodynamic stability of crystalline compounds can limit water solubility and bioavailability in the body.  An alternative is to make the drugs in an amorphous form that is less stable and more soluble.  Unfortunately, this form tends to revert to the crystalline form during manufacture, processing or storage, which can limit its usefulness.   A new paper by Aiguo Zeng et al., aims to increase understanding of the crystallisation of amorphous drugs, using loratadine (shown below) as a model compound.

Quench-cooling amorphous loratadine

Loratadine is a widely-available, non-sedating anti-histamine, used to treat hay-fever and other allergies.  It has been on the market since 1993 and is included in the World Health Organisation’s Model List of Essential Medicines.

Four amorphous samples were prepared by quench-cooling – where molten compounds are rapidly cooled so they have insufficient time to arrange into a crystal lattice.  Study of the samples obtained by cooling at 298 K, 277 K, 253 K and 233 K showed no significant differences in the crystallisation mechanism with quenching temperature.

However, the tendency to crystallise increased with decreasing quench-cooling temperature.  Authors attribute this to the differences in molecular mobility and relaxation of the samples, especially the so-called Johari-Goldstein process of loratadine, involving motion of all atoms in the molecule. This finding will allow the preparation of  loratadine with a lower tendency to crystallise but which retains the beneficial properties of the amorphous form.   It will also inform studies of the amorphous form of other drug molecules.

For more details, read the full paper at:

Ruimiao Chang, Qiang Fu, Yong Li, Mingchan Wang, Wei Du, Chun Chang and Aiguo Zeng  

CrystEngComm, 2017, Advance Article
DOI: 10.1039/C6CE01645F, Paper
_______________________________________________________________________________

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. She published a book, ‘Molecules, Medicines and Mischief’, in 2014, on some of the chemicals found in plants and is currently working on a follow-up.

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Major society chemistry publishers jointly commit to integration with ORCID

ORCID provides an identifier for individuals to use with their name as they engage in research, scholarship and innovation activities, ensuring authors gain full credit for their work.

Today, we signed their open letter, along with ACS Publications, committing to unambiguous identification of all authors that publish in our journals.

The official press release can be read here.

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25th Symposium on Organic Crystals

Congratulations to Mr Asato Mizuno the CrystEngComm presentation prize winner at the 25th Symposium on Organic Crystals which took place from the 18th – 19th September in Koyoto, Japan.

The symposium was organised by the Organic Crystals Division – Chemical Society of Japan. Mr Mizuno’s presentation was titled: ‘Structures and Physical Properties of 3D Crystals Formed by a Triangular π Radical’.

Poster prize winner

From left to right: Prof Rui Tamura, President of Organic Crystals Division – Chemical Society of Japan, Center: Mr Asato, Right: Hiromitsu Urakami

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Poster prize winners at the 66th Japan Society of Coordination Chemistry Symposium

Congratulations to the poster prize winners at the 66th Japan Society of Coordination Chemistry Symposium which took place from the 10th – 12th September in Fukuoka, Japan.  CrystEngComm and Dalton Transactions provided support in the form of poster prizes which were awarded to Takumi Hanaya (University of Tokyo) for his poster titled: ‘Synthesis and Photocatalysis of Mixed Valence Tin Oxide Clusters within Polyoxometalates’ and Takafumi Enomoto (Institute of Molecular Science) for his poster: ‘Near-infrared Light Induced Electron Transfer Reaction Using Distorted Phthalocyanine’.

The symposium is an opportunity for members to exchange ideas in order to contribute to advances in the field of coordination chemistry in Japan. The society is currently composed of 725 ordinary members, 23 Emeritus members, 267 student members, and 12 companies from legal entities. Further information can be found on the webpage.

JSCC 2016 winners

From left to right, front row: Dalton Transactions winner, Takafumi Enomoto and CrystEngComm award winner, Takumi Hanaya bottom right. Standing to the right of Takumi Hanaya is Professor Hiroshi Nishihara, president of the Japan Society of Coordination Chemistry (JSCC) and a member of the Dalton Transactions Advisory Board.

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Increasing pore size in metal-organic frameworks

Many potential applications of metal-organic frameworks (MOFs) rely on the size and nature of the available free volume or pores within the framework structure.  These include use for gas storage or capture and catalysis.   Tuning of the pores is typically achieved by variation of the metal ions or organic ligands.  Lengthening the organic chains can lead to increased pore size but is often limited by a decrease in stability of the framework. A new paper by Yan-Zhen Zheng and colleagues at Xi’an Jiaotong University and the University of Arizona reports a new method of structurally modifying MOFs by insertion of alkali metal ions.

In a series of experiments, a heterometallic MOF with O-containing ligands was modified by the insertion of alkali metal ions into the coordination environment formed by two bridged lanthanide centres.  Initially, 2D or 3D Cu-Pr MOFs were formed with bridging isonicotinate ligands, by reacting isonicotinic acid, CuI and Pr(NO3)3 in a range of organic solvents.  The reaction producing one of these MOFs, {[Pr3(Cu4I4)3(ina)9(DMF)4](DMF)}n (where ina is isonicotinato and DMF is N,N-dimethylformamide), was then repeated with the addition of NaCl, KCl, RbCl  or CsCl.

In the NaCl and KCl reactions, new MOFs were produced incorporating Na+ or K+ ions, with void volumes of 53% and 61%, respectively (compared with 10% for the alkali metal ion free MOF).

Reaction involving the next largest ion, Rb+, produced an unstable MOF which could not be studied further.  However, reaction with the larger Cs+ ion produced a new MOF which didn’t contain this ion, but with a void volume of 59%.

The authors suggest that their method of inducing structural variation using appropriately-sized alkali metal ions should be extendable to other ligand systems for the production of a variety of MOFs with novel structures and functions.

For more information, read the full paper at:
An alkali-ion insertion approach to structurally transform metal–organic frameworks
Yue-Qiao Hu, Mu-Qing Li, Teng Li, Yan-Yan Wang, Zhiping Zheng and Yan-Zhen Zheng
CrystEngComm, 2016, Advance Article
DOI: 10.1039/C6CE00540C
__________________________________________________________________________________________________

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. She published a book, ‘Molecules, Medicines and Mischief’, in 2014, on some of the chemicals found in plants and is currently working on a follow-up.

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Use of nanolimes in conservation

Nanolimes, alcoholic dispersions of colloidal Ca(OH)2 nanoparticles, are commonly used for the conservation of porous materials such as stone and marble.  However, only the basics of the process they undergo – carbonation to produce CaCO3 – are understood and this limits their potential use.

A new paper by Rodriguez-Navarro looks at the carbonation process in detail, with the aims of increasing the effectiveness of and understanding any limitations in the use of nanolimes in conservation.

Conservation of materials using nanolimes is typically carried out in humid air at room temperature.  Under these conditions, amorphous calcium carbonate (ACC) initially forms.  This can then transform into the metastable vaterite (up to 35 wt%) and a small amount of aragonite (up to 5%), but only in the presence of alcohol.  These polymorphs partially dissolve and the stable polymorph, calcite, precipitates.  Alternatively, calcite can form directly after dissolution of ACC.

Nanolime carbonation

Results of the kinetic studies show that the rate-limiting step in the production of calcite is the amount of unreacted Ca(OH)2.  Although the formation of metastable states might be considered a limitation to the use of nanolimes in conservation, the fast kinetics of the vaterite to calcite conversion (72 % in 10 days) means that almost the full consolidation potential can be reached within weeks of application and it is only over very short time-scales that the performance might be sub-optimal.

These results may also have implications for the design of new CaCO3 materials for other applications, using syntheses analogous to the multi-step crystallisation shown in the carbonation of nanolimes in the presence of alcohol.

For more information, read the full paper at:

Amorphous and crystalline calcium carbonate phases during carbonation of nanolimes: implications in heritage conservation

Carlos Rodriguez-Navarro, Kerstin Elert and Radek Ševčík

CrystEngComm, 2016, Advance Article
DOI: 10.1039/C6CE01202G, Paper

__________________________________________________________________________________________________

Gwenda Kyd

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. She published a book, ‘Molecules, Medicines and Mischief’, in 2014, on some of the chemicals found in plants and is currently working on a follow-up.

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Novel photocatalytic heterojunctions

A recent paper published in CrystEngComm details the successful development of BiOBr/WO3 p–n heterojunctions. These novel photocatalysts display higher activity than the individual components across a range of organic molecule pollutants and remain stable for further cycles.

Semiconducting photocatalysts offer a potentially green way of removing organic pollutants from water. Initial development of these photocatalysts focused on TiO2, which shows excellent performance for the decomposition of many organic compounds. However, TiO2 only exhibits this performance under UV light and the development of visible light driven (VLD) photocatalysts is highly desirable. WO3, an n-type semiconductor, possesses many properties needed for a good VLD, but encounters problems related to the recombination of charge carriers.

It is known that the creation of p-n heterojunctions can enhance performance. Enter bismuth oxyhalides, p-type semiconductors which exhibit excellent performance under both UV and visible light. BiOBr in particular, has good chemical stability, acts against a wide range of pollutants, and has never been combined with WO3 before.

Flower-like structures of BiOBr/WO3
Flower-like structures of BiOBr/WO3
The heterojunctions were prepared by solvothermally treating a solution of WO3, Bi(NO3)3 and CTAB. Three different molar ratios were prepared (1/0.5, 1/1 and 1/2) creating flower-like structures. The individual components were also prepared for comparative measurements. Photocatalytic activity was measured by the decomposition of three organic compounds, rhodamine B, methyl orange and para-chlorophenol. The 1/1 compound showed the greatest removal efficiency across all the mock pollutants with all heterojunction ratios performing better than the individual components and a mixture of the two with the same weight of components. The authors explain the excellent performance of BiOBr/WO3 is due to two reasons; firstly the flower-like superstructures of the material with their many pores and channels increase the absorption of small molecules and secondly the nature of the p-n heterojunction allows for efficient charge collection and separation.

The authors conclude the 1/1 compound is the best potential visible light driven photocatalyst with efficient performance and good stability for water environmental purification.

Read the full article here:

Synthesis of BiOBr/WO3 p–n heterojunctions with enhanced visible light photocatalytic activity
Junlei Zhang, Lisha Zhang, Xiaofeng Shen, Pengfei Xu and Jianshe Liu
CrystEngComm, 2016,18, 3856-3865, DOI: 10.1039/C6CE00824K

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