CrystEngComm Blog

Coordination Polymers and Metal-Organic Frameworks are among the most promising crystalline materials for a variety of applications, from gas storage to the detection of hazardous materials. The design, engineering and growth of these materials are pressing challenges, and papers tackling these hurdles are among our most impactful of 2017.

Most Cited Research:

This original research is off to a great start, as some of our most cited work these papers and communications are already receiving recognition from the coordination polymer community.

Template synthesis and photochromism of a layered zinc diphosphonate

Jin-Hua Li, Song-De Han, Jie Pan, Zhen-Zhen Xue, Guo-Ming Wang, Zong-Hua Wang and Zhen-Zhen Bao

CrystEngComm, 2017,19, 1160-1164 DOI: 10.1039/C7CE00212B A layered zinc-diphosphonate templated by protonated 2,4,6-tri(4-pyridyl)-1,3,5-triazine was hydrothermally fabricated. The title compound displays rapid photochromism upon irradiation with UV light or sunlight at ambient temperature.

Two lanthanide-based metal–organic frameworks for highly efficient adsorption and removal of fluoride ions from water

Aiqing Ma, Fei Ke, Jing Jiang, Qiaoyu Yuan, Zhidong Luo, Jianqiang Liu and Abhinav Kumarc

CrystEngComm, 2017,19, 2172-2177  DOI: 10.1039/C7CE00291B The contamination of water with fluoride (F−) is a source of mounting concern for global public health, and the removal of fluoride is quite important and challenging.

A viologen-based coordination polymer exhibiting high sensitivity towards various light sources

Wen-Bo Li, Qing-Xia Yao, Li Sun, Xiao-Dong Yang, Rui-Yun Guo and Jie Zhang

CrystEngComm, 2017,19, 722-726 DOI: 10.1039/C6CE02496C The coordination self-assembly of a photoactive viologen ligand in the presence of a strong electron-donating oxalate anion has successfully afforded a photochromic coordination polymer with high sensitivity not only to ultraviolet-visible radiation but also to X-rays.

Most Cited Reviews:

These Highlight articles are among our most cited of 2017, reviewing the advances and trends that are making waves in the coordination network and MOF community:

Metal–organic frameworks with Lewis acidity: synthesis, characterization, and catalytic applications

Zhigang Hu and Dan Zhao  

CrystEngComm, 2017,19, 4066-4081 DOI: 10.1039/C6CE02660E In this highlight, we review the recent development in the design and synthesis of metal–organic frameworks with Lewis acidity, the characterization techniques of Lewis acid sites, and their applications in heterogeneous catalysis.

Understanding metal–organic frameworks for photocatalytic solar fuel production

G. Santaclara, F. Kapteijn, J. Gascon and M. A. van der Veen

CrystEngComm, 2017,19, 4118-4125 DOI: 10.1039/C7CE00006E The fascinating chemical and physical properties of MOFs have recently stimulated exploration of their application for photocatalysis. Design guidelines for these materials in photocatalytic solar fuel generation can be developed by applying the right spectroscopic tools.

How 2-periodic coordination networks are interweaved: entanglement isomerism and polymorphism

Eugeny V. Alexandrov, Vladislav A. Blatov and Davide M. Proserpio

CrystEngComm, 2017,19, 1993-2006 DOI: 10.1039/C7CE00313G A method of analysis of entanglements in coordination polymers allows the classification of catenation patterns in all known 2-periodic coordination networks.

Submit your research or reviews on coordination polymers and MOFs to CrystEngComm – see our author guidelines for information on our article types or find out more about the advantages of publishing in a Royal Society of Chemistry journal.

Earlier this year we published a Themed Issue focusing on the design strategies for the construction of porous organic materials, including covalent organic frameworks (COFs) and organic cage structures. Featuring contributions from some of the leaders in this captivating field and guest edited by Rahul Banerjee and Neil R. Champness. See their editorial, check out the full contents, or read on for some of our selections of great articles from this issue.

Flexible monomer-based covalent organic frameworks: design, structure and functions   Lanfang Zou, Xinyu Yang, Shuai Yuan and Hong-Cai Zhou CrystEngComm, 2017,19, 4868-4871 http://dx.doi.org/10.1039/C7CE00593H

In this work by Zhou et al. the first example of a COF based on flexible monomers is reported. The material was synthesised by carrying out a Schiff base condensation between a rigid, aromatic carbonyl and a flexible amine. The resulting structure was found to be highly crystalline and porous, with a honeycomb-like hexagonal array of 1D channels (as seen in the cover art). The gas adsorption properties were studied and the material was found to demonstrate promising carbon capture capabilities.

Solid-state inclusion of C60 and C70 in a co-polymer induced by metal–ligand coordination of a Zn–porphyrin cage with a bis-pyridyl perylene derivative Eduardo C. Escudero-Adán, Antonio Bauzá, Laura P. Hernández-Eguía, Frank Würthner, Pablo Ballester and Antonio Frontera CrystEngComm, 2017,19, 4911-4919 http://dx.doi.org/10.1039/C6CE02341J

The interactions between porphyrins and fullerenes is interesting not just from a supramolecular point of view, but also due to the potential photochemical and conducting properties demonstrated by these pairs. In this work by Frontera et al. bis-porphyrin macrocycles are connected into 1D chains using extremely bulky perylene linkers. The size of the linker prevents it from acting as a guest in the porphyrin cage – leaving this site vacant to bind fullerenes as guest molecules. The authors found that occupancy of these cages was 100 % and went on to use computational methods to study the host-guest interactions present in these systems.

Precise elucidations of stacking manners of hydrogen-bonded two-dimensional organic frameworks composed of X-shaped π-conjugated systems Ichiro Hisaki, N. Q. Emilya Affendy and Norimitsu Tohnai CrystEngComm, 2017,19, 4892-4898 http://dx.doi.org/10.1039/C7CE00183E

A problem that has plagued the development of 2D COFs is that they generally exhibit low crystallinity, hindering characterisation. In this work by Hisaki et al. a series of X-shaped building blocks are linked by hydrogen-bonds to form 2D rhombic networks. These sheets stack without interpenetration to form low density frameworks. The aromatic cores of the monomers influence the stacking of these sheets, in two cases resulting in 1D inclusion channels. This in-depth structural analysis of these materials could enhance our understanding of the structures, stacking, and interlayer interactions of 2D COFs.

Modular assembly of porous organic cage crystals: isoreticular quasiracemates and ternary co-crystal Srinu Tothadi, Marc A. Little, Tom Hasell, Michael E. Briggs, Samantha Y. Chong, Ming Liu and Andrew I. Cooper CrystEngComm, 2017,19, 4933-4941 http://dx.doi.org/10.1039/C7CE00783C

In this paper by Cooper et al porous materials are formed by coupling the synthesis of porous organic cages (POCs) with a crystal engineering approach, relying on the intermolecular interactions between cages to direct their co-crystallisation. Rather than rely on the strong, directional intermolecular interactions that are typically used to design co-crystals, but which are often incompatible with cage synthesis, the authors relied on chiral recognition between opposite handed pairs. Combining a chirally pure POC with a helical racemate forms new, quasiracemates in which the POCs stack window-to-window to form diamondoid pores.

Submit your research on porous organic materials to CrystEngComm – see our author guidelines for information on our article types.

Find out more about the advantages of publishing in a Royal Society of Chemistry journal.

CrystEngComm is the journal for innovative research covering all aspects of crystal engineering – the design,  synthesis, crystallisation, and evaluation of solid-state materials with desired properties. Our Editorial Board members are leading researchers in these fields, here are some selections by Tong-Bu Lu and Omar Farha of hot new article in CrystEngComm, as well as some of our favourites! All of these articles are free to access for a limited time.

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.

Green synthesis of zirconium-MOFs

Helge Reinsch, Bart Bueken, Frederik Vermoortele, Ivo Stassen, Alexandra Lieb, Karl-Petter Lillerud and Dirk De Vos  CrystEngComm, 2015,17, 4070-4074 DOI: 10.1039/C5CE00618j

“Zr-based metal-organic frameworks(MOFs) have drawn particularly attention due to their extremely high thermal and chemical stability, which can be used as a platform for various catalytic reactions. However, the synthesis of Zr-MOFs usually uses ZrCl₄ as the starting material, which the reactions should be carried out in organic solvents and prevent the existence of moisture. Recently, Vos and co-workers reported a green synthesis of Zr-MOFs, where the reaction was carried out in water using Zr(SO₄)₂×4H₂O and 2‑aminoterephthalic acid as starting materials, which could enable the synthesis of Zr-MOFs at large scale.”

Experimental and theoretical investigation of a stable zinc-based metal–organic framework for CO2 removal from syngas

Ruiqin Zhong, Jia Liu, Xing Huang, Xiaofeng Yu, Changyu Sun, Guangjin Chen and Ruqiang Zou  CrystEngComm, 2015,17, 8221-8225 DOI: 10.1039/C5CE01320h

“The construction of water resistant MOFs for selectively separating CO₂ from syngas is important for a practical application of MOFs in industry. Zou and co-workers have constructed a micro-porous Zn-based MOF, which shows good framework integrity after guest removal and high water-stability even in boiling water. The titled MOF shows high adsorption selectivity for CO₂ over CO and H₂.”

Professor Omar Farha Professor Farha works at the International Institute for Nanotechnology, based at Northwestern University, USA. His research interests include Rational design of metal-organic framework and porous-organic polymer materials for catalysis, gas storage, gas separations, sensing and light harvesting and the rational design of new shuttles, dyes and fabrications to solve problems involving solar energy conversion.

Sensing-functional luminescent metal–organic frameworks

Dian Zhao, Yuanjing Cui, Yu Yang and Guodong Qian  CrystEngComm, 2016,18, 3746-3759 DOI: 10.1039/C6CE00545d

“Cui and Qian highlighted the recent significant progress on luminescent MOFs and solid sensors for a diverse selection of analytes from explosive chemicals to metal ions and many more. Among many, employing MOFs as a chemical sensor is one of the most promising applications of MOFs and this paper gives a fair summary of the recent advances in the field. I believe that this review can be a very good start point for readers of CrystEngComm who are new to the field and therefore it should be recognized.”

Structure-directing factors when introducing hydrogen bond functionality to metal–organic frameworks

Ross S. Forgan, Ross J. Marshall, Mona Struckmann, Aurore B. Bleine, De-Liang Long, María C. Bernini and David Fairen-Jimenez  CrystEngComm, 2015,17, 299-306 DOI: 10.1039/C4CE01379d From themed collection Metal-Organic Frameworks and Hybrid Materials

“This article highlights a clear example of how noncovalent interactions in SBUs direct the final structure of Zn-based MOFs. Specifically, the authors explain how the incorporation of H-bonding groups on MOF linkers serves as a non-traditional directing agent and results in a different MOF topology when compared to the topology with unfunctionalized linkers. The conclusions drawn are well supported with single crystal data and computational modelling.  Intermolecular interactions, covalent and noncovalent, are an important consideration when predicting MOF topology/properties and designing new MOFs.”

Editorial Office

The CrystEngComm editorial office is based in Cambridge, UK.

How 2-periodic coordination networks are interweaved: entanglement isomerism and polymorphism

Eugeny V. Alexandrov, Vladislav A. Blatov and Davide M. Proserpio  CrystEngComm, 2017,19, 1993-2006 DOI: 10.1039/C7CE00313g

“This highlight article describes the authors’ analytical approach to classifying entangled 2-periodic coordination polymers. Using an extended ring nets (ERNs) approach and their freely available ToposPro software they were able show that 74 % of the 1319 structures analysed fell into only 21 out of 216 topologically distinct modes of entanglement. This work also classifies a novel type of isomerism in coordination networks – referred to as entanglement isomerism. This work will certainly be a valuable resource to crystallographers and chemists working on coordination polymers.”

Synthetic insect antifreeze peptides modify ice crystal growth habit

Charles H. Z. Kong, Ivanhoe K. H. Leung and Vijayalekshmi Sarojini  CrystEngComm, 2017,19, 2163-2167 DOI: 10.1039/C7CE00232g

“Proteins that inhibit ice crystallisation are present in many polar organisms and could find use in food preservation and medical applications. Kong and co-workers investigated synthetic analogues of an antifreeze protein (AFP) found in beetle larvae in which disulphide bonds maintain a secondary structure that orientates hydrophilic side groups outward for ice binding. The authors replaced the disulphide bonds with lactam bridges, increasing stability, and found that although the synthetic analogues were less than half the size of the natural AFP they still showed antifreeze activity upon addition of citrate, giving insight into the potentially synergistic action of AFPs.”

Submit your research on coordination networks and crystal growth to CrystEngComm – see our author guidelines for information on our article types.

Find out more about the advantages of publishing in a Royal Society of Chemistry journal.

This month saw the occasion of the 26^th Symposium on Organic Crystals, organised by the The Chemical Society of Japan Division of Organic Crystals and held from 3^rd – 5^th of November at Yamagata University in Yonezawa, Japan.

The conference was chaired by Professor Hiroshi Katagiri of Yamagata University, and CrystEngComm was on-hand to award prizes to the best oral and poster presentations by young researchers.

The CrystEngComm award for Outstanding Presentation went to Shizuka Anan, of Hokkaido University, for her presentation entitled ‘Stochastic polymerization of monomers fixed in a MOF crystal as its organic ligands’.

The CrystEngComm award for Outstanding Poster went to Haruki Sugiyama, of Tokyo Institute of Technology, for his poster entitle ‘A metal complex with shows photochromism, thermochromism, and mechanochromism – structure-property relationships study’.

	CrystEngComm award winners Shizuka Anan (center left) and Haruki Sugiyama (center right) being presented their awards by division chair, Professor Kazuki Sada of Hokkaido University (left), and RSC representative Hiromitsu Urakami (right).

CrystEngComm offers a hearty congratulations to both prize winners!

When CrystEngComm was established in 1999 as one of the first online-only chemistry journals it published 9 articles in its first twelve months, releasing them online as soon as they were accepted. Since then it has grown to publish more than 1000 articles each year, going from a monthly journal (introduced in 2006) to twice a month (2011) to weekly (2015).  Next year we celebrate our 20^th issue, but ahead of that we’ve reached another milestone – this week sees the publication of our 10,000^th article! 

The article, published in Volume 19, Issue 42, entitled “The impact of hydrogen bonding on 100% photo-switching in solid-state nitro-nitrito linkage isomers” is online now and free to access. We spoke to the authors Dr Lauren E. Hatcher and Professor Paul Raithby from the University of Bath about the work behind the article:

“This paper describing the structural dynamics of light-activated, switchable nitro-nitrito linkage isomers forms part of a programme to develop new materials that will act as molecular switches when exposed to specific wavelengths of visible light.  The overall aim of the programme is to develop new materials that respond rapidly and reliably to changes in the local environment and to send out signals to let us know what is happening.  Our transition-metal nitro complexes, which can be reversibly switched to metastable nitrito isomers, are our benchmark materials in the development of new molecular switches. This is because they are ideal for crystallographic and spectroscopic studies, which provide the exquisite detail that is needed to design more efficient materials using crystal engineering methodologies.”

The Graphical Abstract of the article shows the hydrogen bonding present in the ground state structure of [Pd(Et4dien(NO2)]OTf (left) and the metastable endo-ONO state formed by irradiation at 150K (right).

The work has been highlighted on the front cover of the issue. The cover art shows a stylised view of the experimental set-up. Dr Hatcher shed some light on the experimental procedure:

	“The background to the front cover is based on a photograph of the LED ring array set-up used to illuminate the crystal in-situ on the diffractometer during the X-ray diffraction experiment. The LED ring array is specially designed to place 5 to 6 LEDs in a uniform arc around the crystal, at a distance of approximately 1 cm, which helps to ensure that the crystal is illuminated as evenly as possible. The array is installed on the neck of the low temperature device and can remain in place throughout the X-ray experiment without impeding the data collection. The LEDs can be easily changed, allowing us to use a variety of different excitation wavelengths, and can be operated either as a continuous light source or can be pulsed using a programmable function generator.”

When asked why they chose to publish with CrystEngComm, the authors had this to say:

Congratulations and a huge thanks to Dr Hatcher and Professor Raithby, and all our authors, for helping us reach this milestone!

	Author Profiles:
	Lauren Hatcher completed her PhD in Chemistry at the University of Bath in 2014, on the topic of Molecular Photocrystallography. She has since continued her interest in switchable molecular crystals as a postdoctoral researcher at Bath, studying crystalline switches that respond to different external stimuli including light, temperature, pressure and gas absorption. She received the Leadership Forum Award for Best Chemistry Student at the European SET Awards (2010), and was recently awarded the 2017 CCDC Chemical Crystallography Prize for Younger Scientists by the British Crystallographic Association. Lauren has a growing publication record, which includes an invited contribution to the 2016 CrystEngComm “New Talent” issue (CrystEngComm, 2016, 18(22), 4180-4187).
		Paul Raithby is Professor of Inorganic Chemistry at the University of Bath, prior to which he was a faculty member of the Department of Chemistry at the University of Cambridge for 25 years. He has been awarded the RSC Corday Morgan Medal and Prize (1988) and the RSC Prize for Structural Chemistry (2008). He has over 800 publications and is among the 30 most cited British physical scientists. His research interests span aspects of chemical crystallography, dynamic structural science and co-ordination chemistry. Since 2012 he has led an EPSRC sponsored programme, at Bath, to develop new metastable materials with switchable functionality.

Earlier this year the 67th conference of the Japan Society of Coordination Chemistry (JSCC) was held at Hokkaido University, co-organised by The Chemical Society of Japan (CSJ). Including both fundamental and applied work on synthesis and properties of coordination compounds, encompassing organometallics and bioinorganic chemistry, the event was a huge success with over 1000 attendees. More than 150 talks, in English and in Japanese, were given over three days, including Award Lectures by world-renowned academics Omar M. Yaghi (University of California, Berkeley), Yoshiaki Nishibayashi (University of Toyko), Jian-Ren Shen (Okayama University), and Erwin Reisner (University of Cambridge).

A number of presentation slots were also allocated to students, and the RSC was on-hand to offer poster prizes.  This marks the eighth year running that Dalton Transactions and CrystEngComm have awarded prizes at this event, and this year also saw the presentation of the inaugural Inorganic Chemistry Frontiers awards. Out of a total of 460 poster presentations, the award winners were:

		The CrystEngComm award for outstanding poster presentation goes to Masashi Fujimura, in the group of Ryotaro Matsuda, for his poster entitled “溶存酸素吸着を実現する光応答性ナノポーラス金属錯体の設計“
		The Dalton Transactions award for outstanding poster presentation goes to Shuji Akinaga, in the group of Makoto Fujita at The University of Toyko, for his poster entitled “Inner-functionalization of crystalline meso-porous peptide complexes“
		An Inorganic Chemistry Frontiers award for outstanding poster presentation went to Shuto Mochizuki, in the group of Takashi Uemura at Kyoto University, for his poster entitled “Fabrication of ultrathin polymer films using metal-organic frameworks with 2-D nanospace“
		An Inorganic Chemistry Frontiers award for outstanding poster presentation went to Yoshiyuke Takemoto, of Nagoya Institute of Technology, for his poster entitled “Catalytic silylation of N2 by use of T-shaped cobalt complex bearing iminophosphorane ligands“

The winners were given an RSC heat-sensitive mug as seen in the photo above of Yoshiyuke Takemoto – who we hope doesn’t drink coffee while using that solvent drying system!

The RSC offers its hearty congratulations to all the winners!

The 2017 meeting of the American Crystallographic Association was held in New Orleans from May 26th – 30th. The meeting boasted a packed program featuring lectures, workshops, and poster sessions by range of international presenters from both academia and industry. The CrystEngComm poster prize was awarded to Raúl Castañeda, for his poster Co-Crystals of Dithieno[3,2-a:2′,3′-c]phenazine Derivatives and Trimeric Perfluoro-ortho-Phenylene Mercury.

Raúl was presenting work that he carried out while working towards a Master’s degree with Tatiana Timofeeva at New Mexico Highlands University. Raul’s work focused on studying halogen bonding in compounds for application as inorganic electronics:

Dithienophenazine derivatives are molecules recently synthesized from different groups in attempt to apply them to inorganic electronics. Our group recently synthesized five different derivatives with dithieno[3,2-a:2′,3′-c]phenazine (DTPhz) with equal substituents at 9 and 10 position (H, F, Cl, Br) or pyrido[2,3-b]dithieno[3,2-f:2′,3′-h]quinoxaline (8N-DTPhz). These molecules are very similar in their electronic properties because they have similar band gaps and HOMO levels, but different dipole moments between the halogen derivatives and the non-halogen derivatives. Being very similar as donors make them very good examples to study halogen bonding in donor-acceptor co-crystals with a fully perfluorinated acceptor such as trimeric perfluoro-ortho-phenylene mercury (TPPM). Halogen bonding was important in these co-crystals, since only the donors with halogen substituents lead to co-crystals with mixed donor-acceptor stacks. Unsubstituted DTPhz do not gave co-crystals, and 8N-DTPhz gave a co-crystal where water is blocking one side of the acceptor. The four structures obtained underline the importance of halogen bonding in donor-acceptor co-crystals, as well the impact of different halogens in crystal packing.

Raúl is originally from Chihuahua, Mexico, where he carried out his Bachelor’s degree before moving to the US to study for his Master’s. He then continued moving north to Canada where he is currently pursuing his PhD with Jaclyn Brusso at the University of Ottawa. Besides crystallography, he enjoys playing clarinet for a community band in Gatineau Quebec.