Strategies for improved fabrication of polysaccharide nanofibers

Cellulose nanofibers (CNFs) are used in large amounts in the paper and biomedical industry. The synthesis process, the nature of the catalyst used, and the recyclability of the catalyst has a direct impact on the cost effectiveness of industrial grade CNFs. CNF production follows carboxylation of the primary alcohol groups at the surface of the cellulose fibres mediated by catalyst 2,2,6,6-tetramethyl-1-piperidine-N-oxy radicals (TEMPO). The genotoxic nature of TEMPO suggests the requirement of a lower concentration of the catalyst used during the reaction.

Scheme for different synthesis strategies and characterization of TEMPO mediated CNFs.

Researchers across the world tried a green synthetic approach for CNFs preparation. This also includes successful removal of the catalyst from the product after completion of the reaction. One of the processes employs oxidation of wood pulp fibres using the magnetically recoverable Karimi’s catalyst (TEMPO@SiO2@Fe3O4). The products obtained using the modified catalyst is 5 nm thick cellulose nanofibrils like those obtained in the oxidation mediated by TEMPO in solution. Whereas, the catalyst was easily recovered with a magnet and successfully reused in 4 successive reaction cycles.

Differently modulated TEMPO like SiliaCat TEMPO (a commercial immobilized TEMPO catalyst) and others, show that hybrid sol–gel catalyst allows the synthesis of insoluble polysaccharide nanofibers of superior quality, eliminating waste.

New production strategies involve TEMPO-mediated oxidation followed by homogenisation. The residual hypochlorite can be quenched with 0.3% ascorbic acid to produce chloride and subsequently CNF is separated from the solid catalyst via simple filtration. This dramatically reduced the polysaccharide nanofiber production costs opening the route to large-scale production of functional products where their use has been limited by high cost.

For details: please visit https://pubs.rsc.org/en/content/articlelanding/2021/sc/d1sc03114g

 

About the blogger:

Dr. Damayanti Bagchi is a postdoctoral researcher in Irene Chen’s lab at University of California, Los Angeles, United States. She has obtained her PhD in Physical Chemistry from Satyendra Nath Bose National Centre for Basic Sciences, India. Her research is focused on spectroscopic studies of nano-biomaterials. She is interested in exploring light enabled therapeutics. She enjoys travelling and experimenting with various cuisines.

You can find her on Twitter at @DamayantiBagchi.

 

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ChemComm Milestones – Amit Kumar

Amit Kumar joins our growing community of authors who have chosen to publish their first-time independent research article in ChemComm. Read Amit’s ChemComm1st article ‘Direct synthesis of polyureas from the dehydrogenative coupling of diamines and methanol‘ in the full milestones collection.  In this post, you can find out more about Amit and his exciting research.https://pubs.rsc.org/en/content/articlelanding/2021/cc/d1cc01121

Our interview with Amit

What are the main areas of research in your lab and what motivated you to take this direction?
The discovery of new organometallic catalysts to enable a circular economy is the main theme of research in my lab. Starting my independent academic career with the COVID pandemic has made me realize the onus on scientists and academics to prepare our planet to prevent any future catastrophes. The adverse effects of climate change on the environment have become visible in many forms and is a serious cause of concern in current times. These events have motivated me to utilize my expertise to contribute to mitigating the rising threat of climate change. I have therefore decided to dedicate my academic career in pursuit of sustainable technologies to enable circular economy (that advocates for using waste as a resource) e.g. CO2 capture, and utilization, and production of renewable, biodegradable, and recyclable plastics.

Can you set this article in a wider context?
The article reveals a new proof of concept method for the synthesis of polyureas using the approach of catalytic dehydrogenative coupling of diamines and methanol. Polyureas are commonly used plastics (used for coatings, and adhesives in construction industries) with an annual global market of 885 USD. Polyureas are industrially produced from the reaction of diamines, and diisocyanates. However, diisocyanates and their precursor – phosgene gas are highly toxic. The method disclosed in this article circumvents the use of toxic diisocyanates with methanol, which is not only less toxic and cheaper, but also renewable and can be made from the hydrogenation of CO2. Thus, the developed method is safer than the current state-of-the-art technology and allows the production of renewable polyureas. Moreover, the use of 13C-labelled methanol also allows the cost-effective production of 13C-labelled polyureas that could find applications in medical technologies such as drug delivery, and tissue engineering when coupled with 13C-MRI.

What do you hope your lab can achieve in the coming year?
In the coming year(s), we hope to develop more efficient (cheaper, higher TON, and reusable) catalysts of earth-abundant metals for the production and degradation of polyureas to demonstrate its closed-loop production cycle. Moreover, we also aim to expand this concept to demonstrate new closed-loop production pathways for polycarbonates, and polyurethanes using the approach of catalytic (de)hydrogenation.

Describe your journey to becoming an independent researcher.
October 4th, 2010. Sitting on the first bench of my undergraduate lecture course (taught by Prof. K. R. Justin Thomas, Indian Institute of Technology Roorkee), I studied the fascinating mechanisms of palladium-catalysed cross-coupling reactions. Oct 6th, 2010; Nobel Prize in chemistry was awarded to Heck, Negishi, and Suzuki for the development of palladium-catalysed cross-couplings in organic synthesis. I was thrilled with the news! Partly, because this was the first time, I already knew about the topic that won the Nobel Prize. My interest to delve deeper into this area made me write a review article on this topic in the final year of my undergraduate studies and led me to pursue this area for future research expeditions. I carried my DPhil research with Prof. Andrew Weller at the University of Oxford in the area of organometallic chemistry and then moved to the Weizmann Institute of Science, Israel to work with Prof. David Milstein on topics of green homogeneous catalysis. The work culture of the Milstein lab allowed me to pursue my independent ideas, lead the required collaborations, and work independently on various aspects of publications. These experiences made me confident to lead a research group in academia.

What is the best piece of advice you have ever been given?
I was once told about the 3Ds of leadership/management that I have found very helpful in my career.
Delegate: You cannot do everything by yourself. Effective delegation and collaboration can mean accomplishing the project goal in a limited timeframe and maximizing the utilization of individual team member’s strength.
Defer: Prioritise and defer tasks that can wait.
Delete: Time is precious. It is important to say No to certain tasks that don’t fit with your goals and vision.

Why did you choose to publish in ChemComm?
ChemComm is a highly prestigious journal and has a large readership from several fields of chemistry. Several breakthroughs (including synthesis of fullerenes, and rules for ring closures) have been published in this journal in the past. All of these factors in addition to the rapid peer-review process made me choose to publish in ChemComm.

Amit Kumar completed his Integrated M.Sc. Chemistry degree (2007-2012) at the Indian Institute of Technology (IIT), Roorkee where he received several research fellowships and awards (Indian Academy of Science, DAAD -Germany, IIT-ParisTech, KVPY & INSPIRE from the Govt of India) along with the Institute Silver Medal. He then won the Rhodes Scholarship and pursued his DPhil (2012-2016) under the supervision of Prof. Andrew Weller at the University of Oxford, UK. Upon completion of his DPhil, Amit received the PBC fellowship (Planning & Budgeting Committee, Israel) to carry his postdoctoral research with Prof. David Milstein at the Weizmann Institute of Science, Israel where he was promoted to be a Senior Postdoctoral Fellow in 2019. Amit was awarded the FGS (Feinberg Graduate School) Prize for the outstanding achievements in postdoctoral research 2018 by the Weizmann Institute of Science, Israel. In Jan 2020, Amit started his independent academic career as a Leverhulme Trust Early Career Researcher at the School of Chemistry, University of St. Andrews. His research interests are organometallic catalysis, energy storage, and circular chemistry.

 

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ChemComm 2021 Emerging Investigators collection – videos

In this post you can find out even more about our 2021 Emerging Investigators and their research. Explore the growing collection and head over to our Twitter for the latest updates.

2021 Emerging Investigators – videos

Size-selective synthesis of platinum nanoparticles on transition-metal dichalcogenides for the hydrogen evolution reaction‘ by

 

A mechanism for ageing in a deeply supercooled molecular glass‘ by Andrew Cassidy et al.

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ChemComm Milestones – Stefano Cinti

A warm congratulations to Stefano Cinti for publishing his first independent research article in ChemComm. Be sure to read Stefano’s #ChemComm1st article ‘Merging office/filter paper-based tools for pre-concentring and detecting heavy metals in drinking water‘ in our collection, ChemComm Milestones – First Independent Articles.

We recently caught up with Stefano to find out about his experience as a first-time author. Read about it in our interview below. 

What are the main areas of research in your lab and what motivated you to take this direction?
The main areas are biosensors, smart materials and sustainability. I think the combination of printing technologies and nanomaterials is capable of providing people with very useful analytical tools for improving life’s quality.

Can you set this article in a wider context?
This article represents a general and simple approach for improving decentralized analysis and to strengthen the concept of citizen science.

What do you hope your lab can achieve in the coming year?
I hope my lab, the uninanobiosensors lab, would be able to generate smart solutions for everyone needs monitoring something, in all contexts.

Describe your journey to becoming an independent researcher.
I was fortunate to work in the laboratory of Prof. Palleschi and Prof. Moscone at University of Rome “Tor Vergata”. They gave me all the fundamentals on biosensors and analytical chemistry, always supported me and allowed to spend time abroad. This gave me a wider, international perspective.

What is the best piece of advice you have ever been given?
I think the best advice has been given by observing my labmates at UCSD in the group of Joe Wang. I was a visiting PhD student, and it was clear that to make excellent research you just need your creativity and to work hard.

Why did you choose to publish in ChemComm?
It is a high-quality platform to highlight my research, and also I like the style of the journal.

Stefano Cinti is Assistant Professor at the Department of Pharmacy, University of Naples “Federico II”. He obtained a PhD in Chemical Sciences in the group headed by Prof. Giuseppe Palleschi at University of “Tor Vergata”. He leads the uninanobiosensors Lab (uninanobiosensors.com) and his research includes the development of Electrochemical (bio)sensors, Paper-Based devices, Nanomotors and Nanomaterials. He spent periods abroad in Finland, UK, USA, Germany and Spain. He published more than 45 papers on peer-reviewed journals, with H-index of 27, >2000 citations. In 2018 and 2019 he has been named Best Young Researcher in Bio-Analytical Chemistry and Analytical Chemistry, respectively (by Italian Chemical Society), and in 2020 he has been inserted in World’s Top 2% Scientists. He is in the board of the Chemical Cultural Diffusion group and of the Young Group of Italian Chemical Society. He is the Chair of AMYC-BIOMED, a multi-disciplinary conference for young chemists in the biomedical sciences. He is active in communicating science to non-specialized audience through TV shows, radio and magazine. Find Stefano on Twitter: @S_Cinti87

Find more ChemComm Milestones news on our Twitter: @ChemCommun

 

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ChemComm Milestones – Ashlee Howarth

We are delighted to introduce Ashlee Howarth, our latest #ChemComm1st author. Ashlee’s first independent research article was published in ChemComm in May. Her Communication ‘Synthetic approaches for accessing rare-earth analogues of UiO-66‘ has now been added to our growing collection, ChemComm Milestones – First Independent Articles. Find out more about Ashlee in our interview with her below.

Our ChemComm Milestones interview with Ashlee Howarth

What are the main areas of research in your lab and what motivated you to take this direction?
In my research lab at Concordia, we are interested in the design and synthesis of new rare-earth metal–organic frameworks comprised of multinuclear cluster nodes. We take inspiration from the field of zirconium-based MOFs – materials that I worked with extensively during my postdoctoral studies – where the vast majority of Zr-MOFs contain hexanuclear cluster nodes as building blocks. We are interested in using rare-earth metals to construct MOFs because of the possibility to generate several multinuclear rare-earth clusters (e.g., tetranuclear, hexanuclear, nonanuclear, etc) with varying geometry and connectivity. The diversity of cluster building blocks that are accessible, allows us to synthesize structures that are not as easily attainable (or not attainable at all) using other metals. We are still in the early stages of this research, but our long-term goals are to study these materials for the adsorption, catalytic breakdown, and chemical sensing of hazardous analytes.

Can you set this article in a wider context?
UiO-66 is a zirconium-based MOF that was first reported by researchers from the University of Oslo in 2008 (https://doi.org/10.1021/ja8057953). Since this initial report, there have been over 4,000 publications on the topic of UiO-66. This is because it is a highly robust MOF, built from hexanuclear zirconium clusters bridged by simple terephthalic acid linkers, and has been shown to be potentially useful for applications ranging from gas capture to catalysis to drug delivery. In this article, we report on the synthesis and characterization of eight rare-earth analogues of UiO-66, specifically the Y(III), Eu(III), Gd(III), Tb(III), Ho(III), Er(III), Tm(III), and Yb(III) analogue. We hope to see these rare-earth analogues of UiO-66 become extensively studied over the next decade, just like the Zr-based prototype.

What do you hope your lab can achieve in the coming year?
In the upcoming year, I hope that we can continue to build foundational knowledge with regards to the tips and tricks for synthesizing rare-earth cluster-based MOFs. This includes expanding on knowledge of de novo as well as post-synthetic modification techniques, purification and activation strategies, and methods for characterizing the chemical and physical properties of these new materials.

Describe your journey to becoming an independent researcher.
My journey to becoming an independent researcher began when I completed an Honours specialization project as an undergraduate student in the Corrigan lab at the University of Western Ontario. This was when I first learned about research, the possibility of graduate school, and the steps required to become an independent researcher in academia. From there my love for research, and specifically inorganic materials chemistry, continued to grow as a PhD student in the Wolf lab at the University of British Columbia. I was first introduced to MOFs during my postdoctoral studies in the Farha and Hupp groups at Northwestern University, and it was during my 3 years as a postdoc that I grew to love these materials. I was (and continue to be) fascinated by the fundamental aspects of MOF chemistry, discovering new building blocks, making new network structures, and growing crystals. I also love that MOFs have many potential practical applications due to their high porosities, surface areas, and tunable properties. As such, when finishing my postdoctoral studies I knew I wanted to continue working with MOFs – but I wanted to branch out from working with Zr-MOFs and start exploring the use of rare-earth elements. It’s been quite challenging working on a subclass of MOFs that are entirely new to me, but it’s also been very rewarding, and my students and I learn something new every day.

What is the best piece of advice you have ever been given?
It’s quite hard to choose just one piece of advice, since I have been given lots of great advice from my mentors over the years. One piece of advice that has always stuck with me, which came from my undergraduate supervisor John F. Corrigan, is to always be yourself. It sounds simple enough, but I was giving a practice presentation for my honours thesis defense and I had made pink PowerPoint slides. One of the other students in the group suggested I change the colour since pink might not be the most obvious choice for a professional scientific presentation. John told me to leave the colour if I liked it, and to always be myself. I’ve carried that advice with me throughout my scientific career and it has helped to give me confidence in myself as a scientist – even at times when I don’t always feel like I belong.

Why did you choose to publish in ChemComm?
ChemComm is a great journal with an excellent reputation in chemistry. I always wanted to publish in ChemComm when I was a graduate student but never had the opportunity. When my student, Pedro Donnarumma, was able to find the synthetic conditions necessary to make the first ever rare-earth analogues of UiO-66, I thought that ChemComm would be the perfect venue to disseminate the results quickly and have high visibility within the MOF and materials chemistry communities. I’m very proud to say that my first publication as an independent researcher is in ChemComm and I’m especially proud of the students Pedro Donnarumma (lead author, MSc graduate), Sahara Frojmovic (undergraduate Honours student), Paola Marino (MSc Student), and Hudson Bicalho (PhD candidate) who worked so hard to make it possible! The work also wouldn’t be possible without our awesome collaborator and expert crystallographer Dr. Hatem Titi.

Ashlee J. Howarth was born and raised in London, Ontario. She obtained her undergraduate degree from the University of Western Ontario in 2009, and then went on to do her PhD in inorganic materials chemistry at the University of British Columbia under the supervision of Michael O. Wolf. Before joining the faculty at Concordia, she completed an NSERC Postdoctoral Fellowship at Northwestern University with Joseph T. Hupp and Omar K. Farha. In 2018, Ashlee was recognized by Forbes Magazine as a “30 under 30” in Science for her contributions to research in the field of wastewater treatment, and the detoxification of chemical warfare agents. In 2019, she won the UBC Chemistry Young Alumnus Award, which recognizes a young alumnus whose accomplishments are of such excellence that they provide inspiration and leadership to students and other young alumni. At Concordia, Ashlee is the Concordia University Research Chair in Metal–Organic Frameworks, and the Howarth group is focused on the design and synthesis of rare-earth metal–organic frameworks targeting applications in wastewater remediation, catalysis, and chemical sensing.

 

Explore more ChemComm Milestones news and updates on our Twitter: @ChemCommun

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ChemComm Milestones – Robert Godin

ChemComm Milestones – Robert Godin

Robert Godin reached an exciting milestone this year when he chose to publish his first independent article in ChemComm. You can read Robert’s #ChemComm1st article ‘Experimental determination of charge carrier dynamics in carbon nitride heterojunctions‘ in our growing collection, ChemComm Milestones – First Independent Authors. We are also pleased to confirm that Robert’s significant research now features in our 2021 Emerging Investigators collection too.

To find out more about Robert’s experiences as a first-time author, watch the video interview below.

ChemComm Milestones interview with Robert Godin:

Explore more #ChemComm1st content on our Twitter: @ChemCommun

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One pot synthesis of densely packed poly aryl benzo[a]carbazole

Carbazole based polycyclic aromatic hydrocarbon (PAH) are considered as an important material for organic LED applications. The scalable synthetic approach for PAH still lacks efficiency due to the formation of unwanted by-products. The other issues are often related to high cost of catalysts, harsh reaction condition and multi-step methods. In this aspect, researchers from Indian Institute of Technology Kharagpur, developed a transition metal-free rapid protocol for structurally versatile PAHs.

They have employed a Brønsted acid catalyst for the one pot cascade benzannulation strategy. The reported method allows conjugation of densely functionalized aromatic entities. The first step involves coupling reaction between unprotected 2-arylindoles (nucleophile) and benzyloxy/hydroxy aldehydes (electrophile) in the presence of an inexpensive Brønsted acid catalyst (Scheme1). The course of reaction proceeds through a pinacol-type rearrangement followed by an intramolecular nucleophilic addition leading to poly-aryl benzo[a]carbazole (B[a]C) formation.

After optimizing this step, they have attempted fabrication of carbazole based PAHs with extensive annulated p-conjugation. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone system (DDQ/H+) served as an excellent oxidant for the C–C bond forming reactions due to its high oxidation potential. The oxidative coupling reaction in the anhydrous dichloromethane solvent under an inert atmosphere, stiches number of aryl units together depending upon stoichiometry of DDQ. Appropriate ratio of DDQ and precursors in one-pot generate a challenging ‘‘six–seven–six’’ tricyclic-fused system (Scheme2).

The photophysical characterization suggests B[a]C systems show solvent polarity dependent fluorescence quantum yield. The highly emissive property of these molecules is beneficial for future OLED applications.

For details, please check: Chem. Commun., 2021,57, 5762-5765

About the blogger:

Dr. Damayanti Bagchi is a postdoctoral researcher in Irene Chen’s lab at University of California, Los Angeles, United States. She has obtained her PhD in Physical Chemistry from Satyendra Nath Bose National Centre for Basic Sciences, India. Her research is focused on spectroscopic studies of nano-biomaterials. She is interested in exploring light enabled therapeutics. She enjoys travelling and experimenting with various cuisines. You can find her on Twitter at @DamayantiBagchi.

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ChemComm Milestones – Erli Lu

We were really excited to speak to Erli Lu about his #ChemComm1st article ‘A monomeric methyllithium complex: synthesis and structure‘. This recently published Communication is available to read in our full collection ChemComm Milestones – First Independent Articles. It’s also Open Access.

Find out about Erli and his research in our interview below.

What are the main areas of research in your lab and what motivated you to take this direction?
The main research area of my lab is group-1 and group-2 metal coordination chemistry, for example, lithium, sodium, potassium, magnesium and calcium. Since my PhD, I have studied coordination chemistry of some of the most obscure metals, such as rare-earth and actinide metals. Compared to them, group-1 and 2 metal coordination chemistry are thought to be ‘well-established’. But actually, if looking closely, there are many knowledge gaps in this area. To fill these gaps, I set our research targets towards these ‘familiar strangers’.

Can you set this article in a wider context?
This article is our first step to unveil the unknown face of some of the most common chemical reagents, in this case, organolithium reagents. Organolithium, for example, butyllithium, is arguably the most important organometallic reagents, and the parent of organometallic chemistry. The vital roles of organolithium in numerous organic reactions depend on their aggregates—they exist as oligomers but are postulated to react via the monomers. Chemists want to isolate the monomers, to understand the reaction mechanisms, but this is a formidable task: the monomers are super-reactive and very easy to decompose. In this article, we isolated the first monomer of the archetypical organolithium reagent: methyllithium.

What do you hope your lab can achieve in the coming year?
More exciting complexes, of course! And more papers, for sure! We hope to change an existing prejudice held by chemists that the group-1 and 2 chemistry are not as versatile as d-block and f-block metals, just because they have been studied for over a century.

Describe your journey to becoming an independent researcher.
I decided to pursue a research career since my 2nd PhD year—when I made my first important discovery (the first scandium terminal imide) in Yaofeng’s group at SIOC. This work was published in ChemComm in 2010 and has inspired, influenced and encouraged me since then. The training of a coordination chemist is similar to a Jedi Knight for me: it’s nearly impossible to succeed without a local guru’s help and guidance. I was lucky to meet my two ‘Jedi Masters’: Prof. Yaofeng Chen and Prof. Steve Liddle, who helped me to grow into an independent researcher.

What is the best piece of advice you have ever been given?
‘Grit teeth and carry on’—It is very often (maybe too often) easy to feel frustrated, if not desperate, in a research career. But persistence will be rewarded eventually.

Why did you choose to publish in ChemComm?
I have published 4 Communications in ChemComm, including some of my most important results. From my experience, the two biggest advantages of ChemComm against competitor journals are the rapid reviewing procedure and the professional editorial teams. The handling editors of ChemComm are active academics and do the research themselves—this is very important to ensure a fair and reasonable scientific judgement about a manuscript. Another reason to publish in ChemComm is supporting our local Chemical Society—though it is a less popular practice nowadays than before.

Erli Lu was born in Hefei, China, in 1984. His university degree (BEng) was awarded in 2006 by Tianjin Polytechnic University (China) in Polymer Material Science and Engineering. He joined Shanghai Institute of Organic Chemistry (SIOC), Chinese Academy of Sciences in 2006, studying rare-earth metal coordination chemistry in the Yaofeng Chen group and was awarded the PhD in 2012. In the same year, he moved to the UK as a postdoc researcher with an EU Marie Curie International Incoming Fellowship to join the Steve Liddle group at the University of Nottingham, investigating actinide coordination chemistry. He had stayed in the Liddle group at Nottingham and Manchester from 06.2012-09.2019, before starting his independent career at Newcastle University, as a Newcastle University Academic Track (NUAcT) Fellow. Erli’s group at Newcastle investigates new aspects of group-1 & 2 metal coordination chemistry, including new highly reactive organolithium complexes, low-valent group-1/2 complexes, and their applications in catalysis and energy storage. Find Erli on Twitter: @erli_lu

 

Enjoying #ChemCommMilestones? Follow all of the news and updates on our Twitter @ChemCommun.

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ChemComm Milestones – Benjamin Le Ouay

This April, Benjamin Le Ouay reached an exciting ChemComm Milestone when he published his first independent research article in our journal. You can read Benjamin’s #ChemComm1st article here: Crystalline assembly of metal–organic polyhedra driven by ionic interactions with polyoxometalates

We spoke to Benjamin about his experiences as a first-time author. Read more in our interview below.

What are the main areas of research in your lab and what motivated you to take this direction?
My research group is focused on building new functional materials using metal-organic polyhedra (MOPs) as elementary sub-units. During my previous post-doc experience, I worked on the surface chemistry and supra-particle assembly of Au and Ag nanoparticles, then on MOFs as reactive hosts for polymer guests. Thus, I worked with both nano-objects and with coordination chemistry materials. The current research topics are at the junction of all these previous experiences. I am fascinated by how modular design principles and controlled assembly and disassembly of structures can lead to unprecedented materials’ properties. Porous dispersible cages offer an excellent platform to achieve this goal through careful control of their surface chemistry.

Can you set this article in a wider context?
In this article, I use anionic polyoxometalates (POMs) to drive the assembly of MOPs into crystalline porous networks. Electrostatic interactions are rarely considered when building microporous materials, despite being one of the main stabilizing forces in traditional solid-state chemistry. However, they possess several features that make them very interesting for functional materials chemistry. Therefore, I want to show how the assembly of porous charged MOPs with POMs or other functional counter-ions can lead to a wide variety of new materials with high performances or even unprecedented properties.

What do you hope your lab can achieve in the coming year?
This first article showed the assembly of typical Keggin POMs with two isostructural MOPs. Many more assemblies can be considered, by multiplying the diversity of POMs by that of MOPs. I also plan to dedicate some research effort on preparing other types of functional porous salts.

Describe your journey to becoming an independent researcher.
Becoming an independent researcher took me about seven years. After two years of post-doc in Switzerland, I considered permanent positions, but I felt I was missing something in my chemistry expertise, notably concerning the more “molecular” aspects of materials chemistry. So I went to Japan to work on Polymer@MOF composites. This project was very formative and made me think a lot about how local but also mesoscale interactions can be harnessed to give innovative properties to materials. I also got married in Japan. After five years, I felt ready to take a position and an opportunity offered itself in Fukuoka, so here I am.

What is the best piece of advice you have ever been given?
When you try something, no one can guarantee your success, but if you set yourself for failure, then for sure you will fail. So, always adopt a positive attitude for anything you attempt.

Why did you choose to publish in ChemComm?
With this project, I felt that the most important was to report the main concept early on, before spending more time exploring and taking advantage of the wide diversity of structures that can be reached. For this reason, I chose to report these results as a communication. ChemComm offered the perfect combination of fast publishing, broad audience, and recognized quality.

Benjamin Le Ouay received his PhD in 2012 from Paris 6 University, France. After a post-doctoral experience at Ecole Polytechnique Fédérale de Lausanne (Switzerland) under the supervision of Pr. F. Stellacci, he moved to Japan in 2015 to work with Pr. T. Uemura and Pr. S. Kitagawa on the immobilization of polymers in metal-organic frameworks, first in Kyoto University then at the University of Tokyo. Since 2020, he is an Assistant Professor at Kyushu University (Fukuoka, Japan), working in collaboration with Pr. M. Ohba. His research is focused on the use of porous coordination cages as elementary sub-units for the realization of functional superstructures.

 

You can find Benjamin’s #ChemComm1st article and more in our collection. Don’t forget to head over to our Twitter page for the latest #ChemCommMilestones news and updates.

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Zero valent metal centres in metal-organic frameworks

Crystalline MOF structures with high porosity serve well for a range of applications including shape selective catalysis, gas storage or capture, and drug delivery. These entail the prominence of new methodologies for the synthesis of MOFs, either with unusual metal ion oxidation states or already existing molecular counterparts. In this vein, researchers from TU Denmark have used a ligand transferability strategy for the reaction of homoleptic carbonyl complexes of the Group 6 elements, M(CO)6 (M = Cr, Mo, W), with neutral bridging ligands for the formation of heteroleptic M(CO)6-nLn complexes. For the first time, they have presented the synthesis and characterization of a series of MOFs obtained from M(CO)6 (M = Cr, Mo, W) through the substitution of the ditopic pyrazine (pyz) ligand.

Scheme 1: Synthesis of Cr, Mo, and W.

The synthesis follows reaction at an elevated temperature between M(CO)6 (M = Cr, Mo, W) and an excess of the pyz ligand in a sealed ampoule (Scheme1), leading to dark coloured crystalline products. The reaction is highly favourable for the Mo complex, due to the low dissociation energy of the first Mo–CO bond (119 kJ mol-1), and a reaction temperature of 150°C produced a high yield of crystals. The same reaction conditions provided a minute amount of product for M = Cr and no indication of reactivity for M = W. However, a higher temperature of 200°C lead to the production of the W complex due to the high dissociation energy of the W-CO bond (142 kJ mol-1).

The single-crystal X-ray diffraction pattern of the dark shiny crystals suggests that the composition is fac-M(CO)3(pyz)3/2.1/2 pyz (with M = Cr, Mo, W) (Fig. 1). Cr and Mo crystallize in the triclinic P1 space group, whereas W crystallizes with higher symmetry in the monoclinic C2/m space group. The crystal structure predicts that the three remaining carbonyl ligands reach into the voids of the hexagonal tiling. The hexagon is in chair conformation leading to <M–M–M angles approaching 90° with hexagonal pore channels of roughly 5.5–6.5 Å. The hexagon for W is nearly equilateral in nature compared to Mo, which exhibits unequal hexagon edges.

Fig 1: Single crystal structure of Cr, Mo, and W: (a) View of the hexagonal pore channels in W. (b) Stack of coordination layers in W. (c) Chair conformation of the hexagonal arrangement shown for W. The solvent molecules inside the pores and the disorder are not shown for clarity in (a–c). (d–f) Hexagonal fragments of Cr, Mo, and W together with the pyz molecule contained in the pores (not visible for W due to solvent mask, see methods). The positional disorder of the pyz molecules in W is also shown.

The typical IR absorption band related to M-CO stretching is explored for characterizing the complexes. A red shift of ~310 cm-1 in the spectra of the average carbonyl stretching band was obtained, which is approximated as a ~25% decrease of the force constant associated with the C–O bond. The thermogravimetric analysis showed that the Mo complex has the highest thermal stability with an onset of degradation around 180°C, whereas Cr and W underwent significant mass loss from around 150°C and 130°C, respectively. A similar trend is observed for the stability of the complexes in atmospheric air.

These first examples of structurally characterized zero-valent MOFs with metal nodes derived from metal carbonyls could be attractive architectures for the exploration of catalytic applications as they facilitate the possibility for the non-destructive removal of pore-filling molecules.

 

For further details, please go to:

Zero-valent metals in metal–organic frameworks: fac-M(CO)3(pyrazine)3/2

Laura Voigt, Rene´ Wugt Larsen, Mariusz Kubus and Kasper S. Pedersen*

Chem. Commun., 2021, 57, 3861

About the writer:

Damayanti Bagchi, PhD, is a postdoctoral researcher in Irene Chen’s lab at University of California, Los Angeles, United States. She has obtained her PhD in Physical Chemistry from Satyendra Nath Bose National Centre for Basic Sciences, India. Her research is focused on spectroscopic studies of nano-bio interface and phage therapy. She is interested in science communication and science policy-diplomacy. She enjoys travelling and experimenting with various cuisines!

You can find her on Twitter @DamayantiBagchi

 

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