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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Top 10 Reviewers for CrystEngComm

In celebration of Peer Review Week, with the theme of Recognition for Review – we would like to highlight the top 10 reviewers for CrystEngComm in 2016, as selected by the editor for their significant contribution to the journal.

Dr Igor KasatkinSaint-Petersburg State University
Dr Goutam KoleNational University of Singapore
Professor Dino AquilanoUniversity of Torino
Dr Jack CleggUniversity of Queensland
Professor Huiging Fan, Northwestern Polytechnical University
Dr Joaquin CoronasUniversidad de Zaragoza
Dr Laszlo FabianUniversity of East Anglia
Dr Senthil Kumar PandianUniversity of Delhi
Dr Dongpeng YanBeijing University of Chemical Technology
Dr Jeremy KlostermanBowling Green State University

We would like to say a massive thank you to these reviewers as well as the CrystEngComm board and all of the crystal engineering community for their continued support of the journal, as authors, reviewers and readers.


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Crystal growth control via orientated aggregation.

A recent paper in CrystEngComm details a new synthetic method to create magnenite (iron oxide) nanoparticles (NPs), based on the orientated aggregation of particles using a calixarene macrocycle. The new method allows for control of the type of NPs produced and could potentially be applied to the growth of other nanomaterials.

Magnetite has promising biomedical applications due to its interesting magnetic and electrochemical properties and has been studied for drug delivery, biosensing and cancer treatment.  The NPs can reduce oxidative stress from electromagnetic radiation and raise temperature around the tumour cells in the presence of an applied magnetic field, killing cancer cells through localised heating. In contrast to traditional strategies of crystal growth, orientated aggregation is a mediated approach in which primary crystallites assemble into secondary crystals. The mediator can be other particles, specific molecules or an applied field. NPs grown this way often exhibit different morphologies and properties to the starting material.

Images of multicore (a,b) and octahedral (d,e) NPs

The authors postulated that the use of an organic molecule that complexes with iron could be used to induce aggregation and chose p-tert-butylcalix[8]arene,  calixarene molecules are used in host-guest chemistry to induce efficient and selective hosts.  A reaction mixture of the calixarene, iron(III) acetylacetonate and oleic acid was heated at 200°C for 2 hours, before being refluxed for one hour to promote crystal growth. The initial ratio of the reactants (0.5:1:2) produced multicore NPs with an average size of 40nm and primary crystallites of 7nm. Raising the iron:calixarene ratio to 1:1 resulted in a new morphology being produced, octahedral NPs were now produced exclusively with an average size of 50nm. An experiment without the calixarene produced different NPs again, this time much smaller (7nm) single core NPs. Further experiments varying the heating time and ratios resulted in defect octahedral NPs.

The colloidal and magnetic properties of the NPs were then measured with the multicore structures exhibiting excellent properties. The authors conclude that their synthesis method is easy to perform, reproducible and controllable.

For more information, read the full paper at:

Tuning morphology and magnetism of magnetite nanoparticles by calix[8]arene-induced oriented aggregation

Francesco Vita,  Helena Gavilán, Francesca Rossi, César de Julián Fernández, Andrea Secchi, Arturo Arduini, Franca Albertini and  M. Puerto Morales

CrystEngComm, 2016, Advance Article

DOI: 10.1039/C6CE01252C

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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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CrystEngComm Impact Factor – 3.849

Continuing to excel as the home for innovative research in all fields of crystal engineering!

The 2015 Journal Citation Reports® have just been released and we are pleased to announce that CrystEngComm received an Impact Factor* of 3.849, whilst being the biggest publisher of innovative research covering all aspects of crystal engineering. What’s more is that researchers around the world cited CrystEngComm articles 25,875 times last year, making us the second most cited journal in the crystallography ISI category!

We are truly grateful to all of our authors, referees and readers for contributing to the journal’s continued success, as well as our Editorial and Advisory Boards for their hard work and dedication to the journal. Thanks to you,Graphical abstract: Front coverCrystEngComm has continued to grow from strength to strength and become the journal of choice for many authors and readers!

We invite you to submit your best work to CrystEngComm!

Also of interest: Find out how other RSC journals are ranked in the latest Impact Factor release.

Take a look at a selection of our most highly cited articles listed below:

Highlights

Metal–organic frameworks as heterogeneous photocatalysts: advantages and challenges
M. A. Nasalevich, M. van der Veen, F. Kapteijn and J. Gascon
CrystEngComm, 2014, 16, 4919-4926
DOI: 10.1039/C4CE00032C

Polymorphism in cocrystals: a review and assessment of its significance
Srinivasulu Aitipamula, Pui Shan Chow and  Reginald  B. H. Tan
CrystEngComm, 2014, 16, 3451-3465
DOI: 10.1039/C3CE42008F

Communications

Facile synthesis of single-crystalline NiO nanosheet arrays on Ni foam for high-performance supercapacitors
Ming Huang, Fei Li, Jun Yi Ji, Yu Xin Zhang, Xiao Li Zhao and Xing Gao
CrystEngComm, 2014, 16, 2878-2884
DOI: 10.1039/C3CE42335B

Full papers

Temperature and pH driven self-assembly of Zn(II) coordination polymers: crystal structures, supramolecular isomerism, and photoluminescence
Min-Le Han, Xin-Hong Chang, Xun Feng, Lu-Fang Ma and Li-Ya Wang
CrystEngComm, 2014, 16, 1687-1695
DOI: 10.1039/C3CE41968A

Chemical bonding theory of single crystal growth and its application to ϕ 3′′ YAG bulk crystal
Congting Sun and Dongfeng Xue
CrystEngComm, 2014, 16, 2129-2135
DOI: 10.1039/C3CE42292E

*The Impact Factor provides an indication of the average number of citations per paper. Produced annually, Impact Factors are calculated by dividing the number of citations in a year, by the number of citeable articles published in the preceding two years. Data based on the 2015 Journal Citation Reports®, (Thomson Reuters, 2016).

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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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