Chemical Communications Blog

Congratulations to the 2021 Cram Lehn Pedersen Prize Winner: Amanda Hargrove

19 Feb 2021

We are delighted to announce that Professor Amanda Hargrove, at Duke University, is the recipient of this year’s Cram Lehn Pedersen Prize in Supramolecular Chemistry. This prize, sponsored by ChemComm, is named in honour of the winners of the 1987 Nobel Prize in Chemistry and recognises significant original and independent work in supramolecular chemistry. Our warmest congratulations to Amanda, a well-deserved winner.

“Dr. Amanda Hargrove’s research group has developed small molecules that bind to RNA by interacting with the RNA tertiary structure, such as hairpins, bulges, and stem loops. The combinatorial libraries and maticululas characterization of the small molecules results in very specific RNA binders. Her research group is one of the most prominent groups in the world in recognizing RNA for drug-discovery. Along with discovering that amiloride is a tunable RNA scaffold, her group has published ligands for oncogenic and viral ncRNAs. Expanding on RNA molecular recognition, her group has shown direct evidence that conformational dynamics play a role in RNA binding and developed a method to visualize RNA conformational changes.” Roger Harrison, Secretary of the ISMSC International Committee

Amanda E. Hargrove is an Associate Professor of Chemistry at Duke University and a past ChemComm Emerging Investigator Lectureship awardee. Prof. Hargrove earned her PhD in Organic Chemistry from the University of Texas at Austin followed by a postdoctoral fellowship at Caltech. Her laboratory at Duke works to understand the fundamental drivers of selective small molecule:RNA recognition and to use this knowledge to functionally modulate viral and oncogenic RNA structures. Her passions outside the lab include developing course-based undergraduate research experiences, working toward equity in chemistry at the departmental and national level, and watching old movies with her awesome family. Follow Amanda’s lab on Twitter: @hargrovelab

The 2021 Cram Lehn Pedersen Prize will be celebrated during two days of virtual sessions in July 2021 at 16th International Symposium of Macrocyclic and Supramolecular Chemistry. An in-person event has been rescheduled for 19 – 24 June 2022. The symposium will provide a forum to discuss all aspects of macrocyclic and supramolecular chemistry, and also topics on materials and nanoscience, following the spirit and style of the fourteen preceding conferences. It will also offer networking opportunities among peers, recognized leaders in the field, young scientists, and students.

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ChemComm Milestones – Wooseok Ki

15 Feb 2021

By Harriet Kent, Editorial Assistant.

Our ChemComm Milestones campaign celebrates new, urgent research from emerging scientists. We recently spoke to Wooseok Ki about this #ChemComm1st article ‘Blue-shifted aggregation-induced enhancement of a Sn(iv) fluoride complex: the role of fluorine in luminescence enhancement‘.

Find out about Wooseok’s experiences as a first-time author in our interview below.

What are the main areas of research in your lab and what motivated you to take this direction?
Our primary research goal is to develop and understand the properties of earth-abundant metal based light emitting phosphors using simple solution chemistry. We have developed new tin(IV) halide complex phosphors. Interestingly, our bis(8-hydroquinone)tin(IV) fluoride complex significantly enhances quantum efficiency compared to that of the known, analogous, tin(IV) chloride complex. Furthermore, our tin(IV) flouride complex exhibits interesting aggregation-induced enhancement emission (stronger fluorescence emission in the solid-state than liquid) while the tin(IV) chloride complex does not. Most metal complexes suffer aggregation-induced quenching, weaker emission in the solid-state than liquid, which is a critical issue in OLEDs because OLEDs are fabricated with solid-state film. Therefore, the observed phenomena led to in-depth studies on understanding the role of fluoride ion in the system.

Can you set this article in a wider context?
Most highly efficient metal complexes are composed of expensive rare-earth or noble elements such as Ir, Pt, Re, and Au, which range from 1~90% regarding photoluminescence quantum yield. Despite their excellent performance, one of the drawbacks of using these elements is their high cost elements due to being imported from China. For example, iridium (Ir) costs $41.58 per gram, as reported in 2018, and has been steadily increasing over the years. On the contrary, tin metal is about $0.02/gram. For this reason, abundant, inexpensive transition metal-based complexes have been extensively researched. In our lab, new tin(IV) complexes have been synthesized and characterized by focusing on the effect of halides (i.e., F, Cl, Br, and I) bound to the metal center. In general, the popular way of tuning the optical and electrical properties of metal complexes is to substitute different functional groups in organic molecules(ligands). In our study, we have focused on changing halides bonded with a tin(IV) center with the same organic ligand. Indeed, the choice of halides significantly affects optical, chemical, electrochemical, and structural properties. We are able to tune photoluminescence emission properties systematically. We observed that stronger σ bonding between tin(IV) and fluorine induces significantly improves quantum yield as well as creates aggregation-induced enhancement emission. Our findings would provide to be an important research direction in the way of improving the efficiency of OLEDs.

What do you hope your lab can achieve in the coming year?
In general, the optical emission of metal complexes in the solid-state shows a red-shift with respect to the solution. However, the tin(IV) fluoride complex exhibits blue-shifted aggregation-induced enhancement emission. Therefore, I plan to implement computational studies (Density functional theory) to determine the fundamental mechanism of the fluorinated tin(IV) complex compared with chlorinated tin(IV) complex.

Describe your journey to becoming an independent researcher.
As a materials engineering major, I didn’t explore fundamental chemistry much. My PhD journey allowed me to build up on the fundamental chemistry of inorganic organic hybrid semiconductor materials to understand structure-related properties. After my PhD, I was postdoc at Purdue University and University of Washington, developing earth-abundant thin film solar cells via molecular precursors. Such experiences prepared me as an independent researcher. Furthermore, my industrial experience in Silicon Valley broadened my knowledge and analytical skills, helping to developing my research interests.

What is the best piece of advice you have ever been given?
Failure does not exist in research. Mistakes are stepping stones for new opportunities.

Why did you choose to publish in ChemComm?
ChemComm is a renowned, high-impact journal with fast and excellent support for researchers. The fair review process was the main reason I chose publish in ChemComm.

I am currently an Assistant Professor of Chemistry at Stockton University. I obtained my Ph.D. degree in materials chemistry at the Rutgers University-New Brunswick under the supervision of Dr. Jing Li. After that, I joined Dr. Hugh Hillhouse’s research group at the University of Washington as a postdoctoral associate to develop earth abundant thin film solar cells, such as Cu2ZnSnS4 (CZTS)and PbS. I had industrial experience as a Silicon Valley research scientist developing CZTS thin film solar cells for commercialization. My current research focuses on the synthesis and characterization of new earth-abundant metal complexes.

If you’re interested in reading more outstanding research from first-time authors, head over to our collection ChemComm Milestones – First Independent Articles. You can also find #ChemComm1st related content on our Twitter page: @ChemCommun

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ChemComm Milestones – Anna Kaczmarek

02 Feb 2021

By Harriet Kent, Editorial Assistant.

ChemComm Milestones celebrates emerging authors in the chemical sciences. This week, we spoke to Anna Kaczmarek who recently published her #ChemComm1st article on Ho³⁺–Yb³⁺ doped NaGdF₄ nanothermometers emitting in BW-I and BW-II. Insight into the particle growth intermediate steps.

Find out more about Anna and her research below.

What are the main areas of research in your lab and what motivated you to take this direction?
My lab, the NanoSensing group, was founded in the beginning of 2020 and studies nano-sized optical sensors, specializing in nanothermometers. We have a special interest in interdisciplinary research, where the nanothermometers based on inorganic and hybrid nanomaterials can be combined with other fields such as biomedicine or reaction monitoring. We also focus part of our work on hybrid materials, such as lanthanide-grafted Covalent Organic Frameworks or lanthanide-grafted Periodic Mesoporous Organosilica, which is quite unique in the thermometry field. I have recently obtained an ERC Starting Grant on the topic of thermometry for theranostic applications, so that is currently our main theme in the research group. I have become fascinated with the topic of luminescence thermometry still during my post-doc and I am very happy I have received the chance to build a research lab at Ghent University to explore this fascinating topic.

Can you set this article in a wider context?
There are two interesting findings we have reported in this article – a new thermometry system based on Ho³⁺, Yb³⁺ doped 𝛽-NaGdF₄ nanoparticles as well as the influence of reaction time on the 𝛽-NaGdF₄ particle morphology and unique intermediate morphologies, which are formed during the transformation from 10-15 nm 𝛽-NaGdF₄ spheres to 200 nm hexagonal-shaped particles.

To place the topic of the developed new thermometry system in a wider context it is important to explain that for diagnostic purposes temperature measurements in biomedicine are very important because temperature plays an essential role in biological systems. For biomedical applications accurate measurements in the so-called physiological range are crucial. It is true that detecting the temperature can be done employing more robust, and already commercially available techniques (e.g. thermocouples or infrared imaging), however optical temperature measurements at the nanoscale make it possible to revolutionize the studied resolution and reveal and research phenomena that are otherwise inaccessible to traditional thermometers. In the work we report the excellent thermal sensing capability of Ho³⁺, Yb³⁺ doped 𝛽-NaGdF₄ nanoparticles, where the system is excited into the ⁵F₅←⁵I₈ transition of Ho³⁺ (640 nm) and the ratio of the ²F_5/2→²F_7/2 transition peak of Yb³⁺ and the ⁵I₆→⁵I₈ transition peak of Ho³⁺ were employed for thermometry applications. This system has previously not been explored for thermometry, however offers an excellent thermometer operating in the 1st and 2nd biological window of the human tissue. This type of system can show a high relative sensitivity in the physiological temperature regime upon measurements in water medium, without the need of shielding the Ho³⁺, Yb³⁺ doped 𝛽-NaGdF₄ nanoparticle with any kind of protective silica layer despite its near infrared emission. Therefore, this is a very interesting finding for the luminescence thermometry community, where obtaining highly sensitive near infrared thermometers still remains a big challenge.

What do you hope your lab can achieve in the coming year?
I hope we can find answers and solutions to some current problems in the world of luminescence thermometry. Especially in the biomedical field there are, without doubt, still many challenges ahead of us. Also aiming for multidisciplinary materials is far from a trivial task, so we hope we will be successful in our current undertakings! Luis Carlos, an expert in lanthanide thermometry from Aveiro University, has pointed out at a congress that we need to do efforts to find real applications in the coming 10 years for the thermometers we are developing, otherwise there will be no future for this field. I take these words very seriously and will try my best to make important contributions in the field. On another level, I hope to see my research group grow and I hope I can attract new and enthusiastic researchers to come work with us. Every new person brings in a fresh perspective and a set of ideas how to solve scientific questions. I also hope to see my current students grow as researchers, and I hope that they will find joy in all the discoveries they will make during their PhDs.

Describe your journey to becoming an independent researcher.
I have always known I wanted an academic career. This might have to do with the fact that my father is an academic professor. All the biographies he brought home to me about Marie Sklodowska-Curie, whom soon became someone I idolized, definitely had a huge impact. After obtaining a Master’s degree at Adam Mickiewicz University in Poland, I decided to pursue my PhD abroad at Ghent University in Belgium in the lab of Rik Van Deun. Back then, little did I know that this was the university I would, several years later, obtain a professor title. Although I obtained a tenure track position quite young the journey was not always smooth. Funding was not always easy to acquire and there were moments in my career when I was uncertain of what the future might bring. However, I was fortunate to have people at Ghent University who believed in me and supported me when yet another funding agency rejected my post doc applications. I am very grateful for that. I also have had the opportunity to carry out several very enriching stays abroad in the labs of Francisco Romero-Salguero (Cordoba University) and Andries Meijerink (Utrecht University). They have had a huge impact on my career development and finding my own path as an independent researcher. Many colleagues in the luminescence thermometry community have also had an impact on my growth to become an independent researcher. I am very lucky to work in this supportive community. It was a bumpy road, but 2020 brought many changes. A terrible year due to the COVID-19 outbreak, but for me a very good year in many ways as I was fortunate to have been awarded the Marie Sklodowska-Curie post-doctoral fellowship, a tenure track position at Ghent University and the ERC Starting Grant, all just a few months apart. Now I have lots of work to do, and I hope to show more really exciting and relevant research in the coming years.

What is the best piece of advice you have ever been given?
I am sure there has been a huge amount of very useful advice I have received over the years working in academia and long before that. I know they have had an important impact on my development. But actually the one advice that stuck most in my head comes from a book: “When you want something with all of your heart, the universe conspires to helping you achieve it” – The Alchemist Paulo Coelho. These words kept me dreaming big and not giving up even when I was facing huge obstacles. I believed that if an academic career was what I wanted, and I worked hard enough for it, eventually it would work out. And indeed, it did. Now I am at the start of my new adventure as an independent researcher running my own lab.

Why did you choose to publish in ChemComm?
ChemComm is a renowned journal with a broad readership in chemistry. In general I am very fond of RSC journals as the review time is always fast and the process very clear and transparent.

Anna M. Kaczmarek is a materials chemist studying luminescent nanothermometers and their applications in various fields such as biomedicine, high temperature industry and catalytical applications. She develops nanomaterials mostly based on lanthanide ions, however other systems based on e.g. organic dyes or silver particles have also attracted her attention.
Anna M. Kaczmarek received her master degree in chemistry from the Adam Mickiewicz University in Poznan, Poland in 2010. In 2015 she defended her PhD in Chemstry at Ghent University, Belgium. She carried out post doctoral research in 3 different groups at Ghent University and also carried out several long stays abroad at Cordoba University (Spain) and Utrecht University (The Netherlands). During this time she developed her own research line of luminescence thermometry employing inorganic and hybrid organic/inorganic nanomaterials, MOFs, COFs, and PMOs. In 2020 she obtained a permanent position at the Department of Chemistry of Ghent University (Belgium) and started the NanoSensing group, which will study nano-sized optical sensors and specialize in nanothermometry. Several leading groups in Europe and the world are already studying this important topic, however, to the best of knowledge, the NanoSensing group is the only lab in Belgium studing the emerging topic of nanothermometry. She recently obtained a prestigious ERC Starting Grant on the topic of thermometry for theranostic applications. In her work she is especially intersted in interdisciplinary research where nanothermometers based on inorganic and hybrid nanomaterials can be combined with other fields e.g. biomedicine, chemical reaction monitoring, nanoelectronics.

Find more in ChemComm Milestones – First Independent Articles or on our Twitter, @ChemCommun.

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Toroids or fibres? The different assemblies for scissor-shaped azobenzene dyads

28 Jan 2021

By Samantha Apps, Web Writer.

Imagine if a pile of laundry could spontaneously organise itself into a neat, folded pile of clothes (and how useful this would be!). This principle can actually happen for some molecules in a process known as self-assembly, whereby a molecule or molecules will organise themselves spontaneously to form a supramolecular structure. Molecules can be specifically designed to self-assemble, by relying on the inclusion of functional groups and motifs that create repulsions and interactions to form unique nanostructures and functional materials.

Researchers in Japan have been studying scissor-shaped azobenzene dyads that can self-assemble by folding, using π-π stacking and hydrogen-bonding (Figure 1a and 1b). They previously observed two key self-assembly processes for two example dyads with formation of either toroidal (doughnut-shaped) structures through intramolecular folding, which can subsequently stack onto each other to create tubular motifs; or fibre/ribbon-type structures through one-dimensional helical stacking. The researchers hypothesised that these different self-assembly pathways could be attributed to differences in the degree of intermolecular aggregation of the dyads and set about verifying this using alkylated or perfluoroalkylated azobenzene dyads (2 and 3, Figure 1a) that have different aggregation properties.

Figure 1. a) Structure of azobenzene dyads 1-3. b) Structure of the folded dyad. (c and d) Self-assembly pathways for dyads 2 (c) and 3 (d).

The researchers prepared the supramolecular assemblies of the new dyads by cooling hot solutions (at 90 °C) of 2 or 3 in methylcyclohexane. Both absorption spectroscopy and dynamic light scattering (DLS) measurements indicated self-assembly of the dyads after cooling to 20 °C, and the resulting assemblies precipitated from the cooled solutions with minutes. The structures of these assemblies were then revealed by atomic force microscopy (AFM), showing different nanostructures for 2 and 3. The alkylated dyad 2 assembled into both toroidal and cylindrically extended nanostructures (Figure 2a and b), where the cylinders were composed of stacked toroidal components (as in Figure 1c). On the other hand, the perfluoroalkylated dyad 3 assembled into entangled fibres after cooling (Figure 2c and d), with no well-defined nanostructures observed even with moderate heating.

Figure 2. AFM images of the dyad assemblies after cooling to 20 °C. a) toroids of 2 and b) nanotubes of 2, with insets showing cross-sectional analyses along the orange lines. (c and d) supramolecular fibres of 3 [c) cooling to 20 °C and d) cooling to 30 °C], with inset showing cross-section analysis along the green line.

The researchers investigated the two different self-assembly pathways of 2 and 3 using multiple characterisation techniques. They found that the perfluoroalkylated dyad 3 self-assembles directly into extended fibres as a result of the enhanced intermolecular interactions provided by fluorophilic interactions, whereas the unique toroidal assembly for the alkylated dyad 2 is a result of weak molecular interactions. The extended fibres of self-assembled dyad 3 were found to form organogels at higher concentrations, in which the researchers also studied the photoresponsive properties. Overall, the results confirm the original hypothesis of different self-assembly pathways for dyads with different aggregation properties, and this study will guide future work into creating targets that can switch their self-assembly pathways under external stimuli.

To find out more, please read:

Self-assembly of alkylated and perfluoroalkylated scissor-shaped azobenzene dyads into distinct structures

Hironari Arima, Takuho Saito, Takashi Kajitani and Shiki Yagai *

Chem. Commun., 2020, 56, 15619-15622

About the blogger:

Dr. Samantha Apps recently finished her post as a Postdoctoral Research Associate in the Lu Lab at the University of Minnesota, USA, and obtained her PhD in 2019 from Imperial College London, UK. She has spent the last few years, both in her PhD and postdoc, researching synthetic nitrogen fixation and transition metal complexes that can activate and functionalise dinitrogen. Outside of the lab, you’ll likely find her baking at home, where her years of synthetic lab training has sparked a passion in kitchen chemistry too.

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ChemComm Milestones – Conrad Goodwin

18 Jan 2021

By Harriet Kent, Editorial Assistant.

We were delighted to speak to Conrad Goodwin about his #ChemComm1st article as a corresponding author: Low-spin 1,1′-diphosphametallocenates of chromium and iron. Find out more about Conrad 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?
I’m currently a PostDoc Fellow working at Los Alamos National Laboratory. My main research is into redox, electronic structure, and covalency in transuranium elements, those after uranium. As such I’m always thinking of new ligands and metal-element bonds that might be interesting and help us learn more about how the actinides interact with the rest of the periodic table. These are really scarce resources though, not to mention the radiation hazard, so I’ve got to make use of opportunities to contribute elsewhere as well. I was inspired by some work from my time at Manchester working on anionic transition metal metallocenes, and decided to look into using these phospholide ligands to achieve the same thing and see how the phosphorous would change the bonding and structure. As an added benefit, these new anionic 1,1’-diphosphametallocenates can act as bidentate monoanionic ligands for the other side of my work into actinides.

Can you set this article in a wider context?
Metallocenes are everywhere: ferrocene even works as an anti-knocking agent in petrol for cars. The oxidation (taking an electron away) of metallocenes is also a defining feature, and one many chemists will be familiar with. Whether that’s simply because they’ve seen the [Fc]^+/0 couple in electrochemisty, used [Co(Cp*)₂] as a reducing agent, or perhaps they’ve seen a popular f-element version like [Sm(Cp*)₂]. But going the other way, reduction (adding an electron), has been barely explored until recently with the report of [Mn(Cp*)₂] anions and [M(Cp^ttt)₂] (M = Mn, Fe, Co; Cp^ttt = {C₅H₂–^tBu₃}). The former [Mn(Cp*)₂] anion is really stable, it’s an 18e metallocene – but the latter Cp^ttt examples were all very temperature sensitive.
What we tried to do here was use a slightly different ligand set to try and hit a middle-ground between these stability extremes, and address two problems we saw with the previous examples: 1) the steric bulk of Cp* and Cp^ttt help stabilize those complexes but also make the metal quite inaccessible to do any further chemistry; 2) by adding a Lewis-basic phosphorous into the ligand we have added a binding site which means we have an anionic complex where the charge is spread across two rings, and a metal of our choosing in the middle. I think this has the potential to be a very interesting new ligand set, complementary to the ubiquitous ferrocenophane class, but where the anionic charge formally resides at the metal.

What do you hope your lab can achieve in the coming year?
The coming year (2021) is actually my last at Los Alamos, and hopefully my last as a PostDoc. I’m hoping to make the move to run my own research group by the end of 2021. As for my current work, we have several transuranium projects that are wrapping up, and whose publication I hope will excite the broader chemical community about these elements. We’ve got some work comparing lanthanide and actinide covalency, a topic that’s really relevant now as the debate surrounding green energy and nuclear fuels continues, and another exploring organometallic chemistry right at the edge of the periodic table.

Describe your journey to becoming an independent researcher.
I’m currently in a halfway house towards independence. After my PhD I was lucky enough to receive an EPSRC Doctoral Prize which was a 1-year PostDoc Fellowship to do a short research project based on my own proposal, but within an established lab. I finished this and then moved to Los Alamos as a J. Robert Oppenheimer Distinguished Postdoctoral Fellow which again was to do work that I proposed to do but I’m still supervised by a mentor (Andrew Gaunt). So this afforded me the flexibility to pursue a little piece of independent research on the phosphametallocenes here. As for my next steps to independence, my work at Los Alamos working with transuranium elements has afforded me a skillset and expertise with an area of the periodic table not many get to work in. So I’m trying to leverage this towards an independent career and research group working in this area.

What is the best piece of advice you have ever been given?
“Have you tried crystallizing that from toluene?” – David P. Mills, in regards to every molecular compound ever. But jokes aside, I’ve been fortunate enough to meet and learn from some of the giants in the molecular f-element research field, and they have all said some variation of: “Approach research with an open mind and question established dogma”. This is so important, and applies to every level of doing basic research. It can be as simple as: whatever way you were taught to do something doesn’t have to be the only way – so learn from others; to not assuming that certain elements behave a certain way and going out of your way to dispel that assumption. I know of at least one academic who tries to recruit PhD students from outside of their own research field so that they come to their lab with a blank slate and won’t be tempted to assume something will/won’t work.

Why did you choose to publish in ChemComm?
I’m a big fan of the RSC’s activities and also the publishing model. ChemComm has a really broad readership and I wanted this work to be seen and help ignite this new area of research into anionic metallocenes. On top of that the editorial team were incredibly helpful and responsive, which made the whole process really easy.

Conrad Goodwin undertook both graduate and doctoral studies at the University of Manchester, completing a PhD in f-element silylamide chemistry with Dr David Mills in 2017. He then undertook a one-year EPSRC Doctoral Prize fellowship focussed on low-coordinate and low oxidation-state amido and organometallic lanthanide complexes as precursors to record-breaking single molecule magnets. In 2018 he subsequently moved to the United States to undertake a J. Robert Oppenheimer Distinguished Postdoctoral Fellowship at Los Alamos National Laboratory with Dr Andrew Gaunt. His research interests focus on the interrelation of oxidation state and covalency in transuranium elements, and on organometallic transuranium chemistry. Find Conrad on Twitter: @ConradGoodwin

Read Conrad’s #ChemComm1st article and others in ChemComm Milestones – First Independent Articles. Follow the hashtag #ChemCommMilestones on our Twitter page for more: @ChemCommun

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ChemComm Milestones – Artur Kasprzak

11 Jan 2021

By Harriet Kent, Editorial Assistant.

It is the start of 2021 and we want to talk about more emerging scientists in our community. Beginning with Artur Kasprzak who recently published his #ChemComm1st article: ‘Disaggregation of a sumanene-containing fluorescent probe towards highly sensitive and specific detection of caesium cations‘.

Read our interview with Artur below.

What are the main areas of research in your lab and what motivated you to take this direction?
My lab is working in various areas of chemistry, including ferrocene systems, magnetic nanomaterials, biologically active dendrimers, sumanene-tethered systems, pi-conjugated molecules, and many more. We are a young group of organic and materials chemists. The compounds and materials that we create might offer many interesting properties and applications, such as catalysis or analyte recognition. All these points make us passionate about our fields of enterprise.

Can you set this article in a wider context?
In this ChemComm article we merged several topics in chemistry, namely (i) modification of sumanene, a fullerene fragment exhibiting many interesting properties, (ii) aggregation-induced emission enhancement effect (AIEE), which is a unique property that has not been commonly reported for sumanene-derived compounds, (iii) caesium cation (Cs+) induced disaggregation feature. The last point of our work is especially interesting, since site-selective Cs+ recognition is indeed the novel feature of sumanene derivatives that has been explored by my group and the group of prof. H. Sakurai (Osaka University). Additionally, it has an important wider application, since Cs+ detection is of a highest environmental because significant amounts of caesium has been detected in many radiated, post-disaster areas (like after the nuclear plant accident Fukushima-Daiichi in 2011). With our compound we can detect such low Cs+concentrations like 1.5·10-7 M !

What do you hope your lab can achieve in the coming year?
Hopefully, many great things! Now, we are intensively investigating ferrocene and sumanene chemistry and we anticipate that these chemistries can provide such wonderful results as these recently published in ChemComm. My research group has recently been preparing new organized structures bearing ferrocene or sumanene motifs, so we would like to study these exciting chemistries even more and publish these results in such respected journals as ChemComm. We are always seeking for potential collaborators so we would like to expand our areas of enterprises in the coming year.

Describe your journey to becoming an independent researcher.
From the very beginning of my scientific career, I was fortunate enough to collaborate with many great scientists that have been very kind and inspirational. Now, I appreciate it even more than before. I think that expanding the research horizons and scientific interests was the thing that enabled me to become an independent scientist that can collaborate with many researchers in various interesting fields. In my opinion everything is about enjoying the chemistry and seeing beyond your areas of enterprise. In my case, continually expanding the knowledge in various fields and keeping in touch with many experts really stimulated my independent researcher career. Now, I do my very best to guide my students through the same scientific career path that once I undertook.

What is the best piece of advice you have ever been given?
Work hard and be creative. To me it sounds like the best way to become a great scientist!

Why did you choose to publish in ChemComm?
In my opinion, ChemComm is the world’s leading chemical journal that publishes cutting-edge articles in general chemistry. Thus, when we considered the most suitable journal to publish these interesting results, ChemComm was our first choice! Additionally, I have also had many good experiences in publishing with RSC, because of its professionalism at every publication step as well as fast publications times.

Artur Kasprzak received his B.S. (2015), M.S. (2016) and PhD (2020) in Chemistry from Faculty of Chemistry, Warsaw University of Technology (Poland) under the supervision of Prof. Mariola Koszytkowska-Stawinska and Dr. Magdalena Poplawska. He has also spent half a year in the group of Prof. Hidehiro Sakurai at Osaka University working on the applications of sumanene-containing molecules towards the design of Cs+ recognition materials. His PhD thesis was focused on the synthesis and applications of functional materials based on the carbon-encapsulated iron nanoparticles. Now, working as an assistant professor at Warsaw University of Technology and leading a young research group (Functional Organic Compounds Group, a subgroup of Biofunctional Materials Group) he explores the chemistry and applications of π-conjugated molecules, metallocene-tethered systems and nanomaterials.
ORCID: 0000-0002-4895-1038
Researchgate: https://www.researchgate.net/profile/Artur_Kasprzak
www: http://zcho.ch.pw.edu.pl/skl_kas.html

Read Artur’s work and more #ChemComm1st articles in ChemComm Milestones – First Independent Articles. Follow us on Twitter @ChemCommun.

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One-dimensional carbon ladders

05 Jan 2021

By Samantha Apps, Web Writer.

Nanomaterials are small and mighty. Scaling down to the molecular level imparts desirable properties to materials, for example high conductivity that is useful for electronic applications. Conjugated polymers (CPs) are one-dimensional nanomaterials with promising potential in optoelectronics and spintronics, due to their enhanced conductivity as a result of the delocalised π-electrons along the backbone of the polymer. Doubly-linked CPs, referred to as π-conjugated ladder polymers, have more unique features compared to their singly-linked counterparts, but such nanomaterials are often difficult to synthesise.

Polycyclic aromatic molecules such as acenes have shown potential as organic semiconductors and are therefore ideal materials for new CPs, but polymer formation by coupling the acenes is limited by repulsions between hydrogen atoms of adjacent acene motifs. These constraints can be overcome by installing wider ethynylene or cumulene π-conjugated bridges between the acenes, as demonstrated by researchers from Spain and the Czech Republic in their design and synthesis of a new one-dimensional π-conjugated ladder polymer (Figure 1). This ladder polymer is based on doubly-linked pentacenes (5 linearly-fused benzene rings).

(a) shows the chemical structures in a scheme of the precursor (brominated pentacene) and the polymer structure (ladder pentacene polymer), where the pentacene is 5 linearly fused benzene molecules. (b) and (c) show brighter spots on a dark surface that correspond to the chains of new polymer, where in (c), the individual pentacenes can be differentiated (d) and (e) show even more detail where the fine structure of the pentacenes and linkages of the polymer can be made out.

Figure 1. (a) The synthesis of the ladder polymer, starting from the 8BrPN precursor. (b) Wide STM image showing chains of the new polymer on the Au(111) surface. (c) Close-up high-resolution STM image of one polymer chain corresponding to the green rectangle in (b). (d) nc-AFM image of the molecular structure of the ladder polymer. (e) Simulated nc-AFM image of (d).

The new conjugated ladder polymer was synthesised by vacuum deposition of the precursor molecule (5,7,12,14-tetrakis(dibromomethylene)-5,7,12,14-tetrahydropentacene, 8BrPN) onto a gold surface, Au(111). Subsequent thermal treatment up to 360 °C resulted in the formation of ethynylene linkages between the pentacenes, forming a ladder polymer on the gold surface (Figure 1a). The researchers determined the ladder polymer structure using scanning tunnelling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) techniques, as shown in Figure 1b-e. The STM images showed mostly one-dimensional chains with some disordered segments (Figure 1b), and the close-up image in Figure 1c confirms the double-linkages between each pentacene. The nc-AFM images show even more detail, confirming that the backbone of the polymer contains the pentacenes, doubly-linked to adjacent moieties in the 5,7,12 and 14 positions (Figure 1d/e). The nc-AFM characterisation also confirmed ethynylene (–C≡C–) rather than cumulene (=C=C=) linkages, shown by the brighter regions in the middle of the connections that correspond to the ethynylene triple bonds.

The researchers also probed the electronic structure of the new polymer on the gold surface using scanning tunnelling spectroscopy (STS). They determined an electronic bandgap that is 0.22 eV larger than that of a singly cumulene-linked pentacene polymer, thus demonstrating the advantages of the ladder-type structure in this instance. The technique used to create the pentacene ladder polymer in this report could be adopted for the creation of other π-conjugated ladder polymers with varying acenes, which could ultimately be useful for new nanomaterials in optoelectronics and spintronics.

To find out more, please read:

On-surface synthesis of doubly-linked one-dimensional pentacene ladder polymers

Kalyan Biswas, José I. Urgel, Ana Sánchez-Grande, Shayan Edalatmanesh, José Santos, Borja Cirera, Pingo Mutombo, Koen Lauwaet, Rodolfo Miranda, Pavel Jelínek,* Nazario Martín* and David Écija*

Chem. Commun., 2020, 56, 15309–15312

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ChemComm Milestones – Thanthapatra (Valentine) Bunchuay

14 Dec 2020

By Harriet Kent, Editorial Assistant.

Exciting news – Thanthapatra (Valentine) Bunchuay recently published his #ChemComm1st article:
Pertosylated pillar[5]arene: self-template assisted synthesis and supramolecular polymer formation. We wanted to find out about Thanthapatra’s experiences reaching a ChemComm Milestone. Find out more in our interview below.

Read about Thanthapatra and the SupraValentine group here:

What are the main areas of research in your lab and what motivated you to take this direction?
Our research in the ‘SupraValentine’ Lab at Mahidol University focuses on supramolecular and macrocyclic chemistry, which covers a broad area of interests. Learning from molecular recognition processes in nature, our lab has employed various forms of intermolecular non-covalent interactions as tools to construct supramolecular architectures. Our prime interest is the synthesis of novel macrocyclic host molecules decorated with specific functional groups to facilitate binding or encapsulation of target guest species including cations, anions, ion-pairs, and neutral molecules. These systems have been designed to self-assemble into complex nanostructures for tailored applications such as; stimuli responsive materials, smart sensors, and recovery and extraction agents. The most effective and elegant supramolecular chemistry is performed by nature and so taking inspiration from biological systems, complemented by one’s own imagination are key to my research in supramolecular chemistry. I am motivated by the idea of inspiring others to actively contribute to the exciting field of supramolecular chemistry, which is still a relatively small society in Thailand.

Can you set this article in a wider context?
Pillar[5]arenes are a class of macrocycles having a five-fold symmetric structure constructed from electron-rich aromatic surfaces. These macrocycles can encapsulate a range of guest molecules and especially electron deficient linear alkyl moieties. Usually, these are obtained by Lewis acid catalyzed macrocyclization reactions of dialkoxy benzene monomers. However, to date the synthesis of highly decorated Pillar[5]arenes has been hindered by low yields and/or tedious synthesis. In this work, we incorporated tosylate functional groups into the monomeric unit to synthesize a pertosylated pillar[5]arene structure. The discovery of a serendipitous self-templation effect facilitated the high yielding synthesis (70%) of a perfunctionalised pillar[5]arene derivative, in contrast to the previous paradigm for decafunctionalised pillararenes of this kind. The presence of ten tosylate units not only facilitates the formation of a supramolecular polymer and nanofiber in both the solid-state and solution phase, through concerted weak hydrogen bond formation, but serves as an excellent synthetic handle in the rapid construction of highly derivatisable and multivalent nano-scafffolds. We believe that these results provide great promise for the versatility of subtle, yet powerful, unorthodox non-covalent interactions in the synthesis and functionality of supramolecular systems. Considering the rich host-guest chemistry of pillararenes we hope that our contribution to the rapid and facile access of diversifiable platforms will help further propel the inherent ‘stardom’ of pillararene based materials.

What do you hope your lab can achieve in the coming year?
My lab has been set up since August 2019. Thanks to the unfailing kindness and generosity of my previous M.Sc. supervisor, Assoc. Prof. Jonggol Tantirungrotechai I have been able to kick-start my research career. Jonggol’s sharing of space and facilities were crucial to my first independent publication. In this coming year, we hope that we will discover many secrets of nature through our systems and aim to communicate our work to the chemist community (publish more articles!). Again, thanks my students and my great colleagues especially, Prof. David Harding for your effort.

Describe your journey to becoming an independent researcher.
It’s been a long journey I would say. Since grade 10 in high school, I have received a Development and Promotion of Science and Technology Talent Project (DPST) scholarship from the Thai government to study any ‘pure science’ until Ph.D. and without hesitation chose a chemistry major. I received my B.Sc. (2011) and M.Sc.(2014) from the Faculty of Science in Mahidol University, Thailand. During that time, I was allowed to explore a broad range of chemistry from iodine mediated synthetic methodology to the post-functionalisation of MOFs for catalysis. In 2014, I had a great opportunity to join the research group of Prof. Paul D. Beer at the University of Oxford. During this time, it is no exaggeration to say my life was totally changed. It was truly an honour to be under the supervision of Paul leading with uninhibited imagination, enthusiasm and encouragement, undoubtedly influencing how I pursue science in my own research group. Apart from synthetic chemistry skills, I also learnt to be patient and deal with the dynamics of a large research group. In particular, recalling the valuable discussions with Paul and other group members helping to stimulate my own research interests. Sometimes my ideas were useful and of course some were useless, but all were useful learning experiences nonetheless. In January 2019, I secured the position of inorganic lecturer at Department of Chemistry, Faculty of Science, Mahidol University, Thailand. Starting my own research group in August 2019 with one graduate student and two undergraduate students, 10 months later we were lucky enough to publish our first work in ChemComm.

What is the best piece of advice you have ever been given?
During my time as a D.Phil student, it was certainly the most transformative and important journey of my life. I started in the Beer group with little synthetic organic experience, so my first year was a steep (but fun) learning curve. Sometimes we succeeded, many times we failed. As Paul always says “Learn to walk before you can run”, you have to keep learning, doing chemistry, and developing yourself gradually. The day that you are strong enough, you can run and jump into whatever areas that you are not familiar with. Another invaluable piece of advice from him that I really like is “Good work can be published everywhere”, however he said this when our first paper together was rejected!

Why did you choose to publish in ChemComm?
ChemComm consistently publishes many excellent works. The journal’s universally respected reputation presented the best platform to initiate my independent scientific career. The clear paper format and straightforward submission processes were also important in my decision to submit our very first publication from the ‘SupraValentine Lab’. Many thanks to the Royal Society of Chemistry (RSC) and ChemComm again for this great opportunity to support early career researchers from wherever they are in the world. This experience has encouraged me and I hope it will inspire others to continue producing good science.

Thanthapatra (Valentine) Bunchuay, a recipient of the Royal Thai Scholarship (2004 – 2018), graduated from Mahidol University (Thailand) with a first class honour B.Sc. degree in 2011. After that, he carried on the research with Associate Professor Jonggol Tantirungrotechai in the functionalisation of metal-organic frameworks (MOFs) for heterogeneous catalysis applications, graduating with an M.Sc. degree in chemistry in 2014. In the same year, he moved to the United Kingdom to join the group of Professor Paul Beer at the University of Oxford, where he developed sigma-hole donor host molecules for anion and ion-pair recognition in aqueous media. Having finished his D.Phil. degree in 2018, he is now working as an inorganic chemistry lecturer at Mahidol University where he has started The SupraValentine Research Lab. His research focuses on applications of supramolecular host-guest chemistry in functional materials and nanostructures.

Our collection of #ChemComm1st articles, including Thanthapatra’s, are available here. Don’t forget to follow us on Twitter for the latest #ChemCommMilestones news.

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ChemComm Milestones – Hennie Valkenier

09 Dec 2020

By Harriet Kent, Editorial Assistant.

Our ChemComm Milestones campaign aims to highlight authors who have published their first independent research article in our journal. We were excited to speak to Hennie Valkenier about her experiences as an emerging author and her #ChemComm1st article: Transmembrane transport of copper(i) by imidazole-functionalised calix[4]arenes.

Read our interview with Hennie here:

What are the main areas of research in your lab and what motivated you to take this direction?
Our main area of research is the development of synthetic transporters for ions and we have a particular interest in the transport of phosphate and phosphorylated compounds, for which I received an ERC starting grant (ORGANITRA). I have always been fascinated by the possibility that chemistry offers to design compounds for any purpose and to then actually synthesise and test these compounds. This process of molecular design, synthesis, and testing allows, firstly, to deepen our understanding of how these compounds function, and secondly, to develop new materials or applications. During my PhD, I worked on organic compounds for applications in molecular electronics. After my PhD, the many health challenges that our society faces and my interest in biological processes prompted me to reorient my research towards supramolecular chemistry. This allowed me to follow my passion to design, synthesise, and study compounds, now with the purpose of transporting ions through lipid bilayers. This research has many fundamental aspects, but also offers perspectives on medical purposes (Chem. Sci. 2019).

Can you set this article in a wider context?
The research efforts on ion transport by synthetic compounds have increased rapidly over the past 20 years. The vast majority of this work focusses on only a limited number of ions (such as Na⁺, K⁺, and Cl⁻), for which the methodology to study the transport process has been well established. The transport of these anions is indeed very important in biology, for instance in signal transduction and homeostasis. However, the transport of other ions, including phosphates and Cu⁺, also plays a crucial role in biology, while little or no research has been done to try and mimic these processes with synthetic systems. The challenge is that this requires not only the development of compounds that could bind and potentially transport these ions, but also the methodology to study the transport process. Nathan Renier is the first student who had the courage to start a PhD under my supervision and in this ChemComm article we show that it is indeed possible to transport Cu⁺ through lipid bilayers with synthetic compounds and to monitor this process by fluorescence spectroscopy. These results encouraged us to start exploring the biological effects of Cu⁺ transporters.

What do you hope your lab can achieve in the coming year?
First of all, I hope that the different team members can continue to grow as researchers and enjoy discoveries (whatever their scale) and hard work paying off. We also hope to find new synthetic transporters, deepen our understanding of transport processes, and transport challenging ions such as phosphates. And with Nathan and various collaborators we hope to demonstrate that we can transport Cu⁺ into cells.

Describe your journey to becoming an independent researcher.
I am firstly grateful to all my supervisors for their continuous support combined with the freedom to develop my research projects, to try new things, and pursue ideas even if only some of them turned out well. In Groningen, Kees Hummelen allowed me to reorient my research project and set up collaborations with specialists in the field, to work at the forefront of molecular electronics. In Bristol, Tony Davis has introduced me to the field of supramolecular chemistry and ion transport during the 3 years I worked with him as a postdoc. In his group, I also had the privilege to work with several PhD students, allowing me to gain experience in supervision. Through the “Supramolecular Chemistry in Water” COST network, I met with Kristin Bartik and Gilles Bruylants from Brussels (ULB), whose “Engineering of Molecular NanoSystems” laboratory I joined to look at anion binding and transport from a rather different perspective. They also taught me and supported me in the writing of grant proposals, starting with small grants for equipment, to later arrive at the grant for my permanent research position with the national research council FNRS and an ERC starting grant, which launched my career effectively.

What is the best piece of advice you have ever been given?
When thinking about grant proposals, my colleagues at the ULB told be to dream big. It feels safer to propose a project that is close to what is known to work, but aiming for something that we can currently only dream about is worth the risk. Another very good piece of advice, from Tony Davis, concerns publishing results: Tell a story. Research data is indispensable, but rationalising the trends observed and drawing conclusions that are more general and teach lessons that are also applicable to the research projects of other people is a lot more interesting.

Why did you choose to publish in ChemComm?
ChemComm reaches a very broad audience, which is a great platform for our interdisciplinary research. Furthermore, the clear and concise format of ChemComm is highly suitable for a proof-of-concept article. I also had good experiences with the RSC, in their fair and professional handling of manuscripts. Thus, we were delighted to see Nathan’s first article on Cu⁺ transport published in ChemComm.

Hennie Valkenier studied Chemistry at the University of Groningen and obtained her PhD from this university in 2011 with a thesis on Molecular Electronics, supervised by Prof. Kees Hummelen. After a year of teaching in West-Africa, she joined the group of Prof. Tony Davis at the University of Bristol as a post-doc to develop transmembrane transporters for chloride. In 2015, she moved to the Université libre de Bruxelles (ULB) to work as a post-doc with Profs. Kristin Bartik and Gilles Bruylants in the Engineering of Molecular NanoSystems laboratory, where she obtained a permanent position as FNRS Research Associate in 2018. Her research efforts focus on the development of receptors for the transmembrane transport of ions.

Find Hennie’s work, and other #ChemComm1st articles, in ChemComm Milestones – First Independent Articles.

Find out more on our Twitter #ChemCommMilestones #ChemComm1st.

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Breaking the rules of valency for silicon and germanium

30 Nov 2020

By Samantha Apps, Web Writer.

As every chemist knows, carbon likes to play by the rules and is almost always tetrahedral and tetracoordinate. There are exceptions to this geometry though; examples of planar tetra-, penta- and hexacoordinate carbons have been experimentally detected or theoretically predicted. The other group 14 elements also behave similarly to carbon, but again, planar tetracoordinate (pt) or planar hexacoordinate (ph) silicon or germanium atoms have been reported as exceptions to the tetrahedral, tetracoordinate standard.

Planar pentacoordinate (pp) silicon (ppSi) atoms are desirable in 2D materials, and researchers in China and Mexico have now reported the first examples of planar pentacoordinate silicon and germanium atoms (ppX, where X = Si, Ge). The researchers used a ‘π-localisation’ approach in their design, where the formation of multiple bonds between the surrounding ‘ligand’ atoms and the Si or Ge centre led to viable ppX atoms in XMg₄Y^– (X = Si, Ge; Y = In, Tl) or SiMg₃In₂ structures (Figure 1).

Structures of the two planar pentacoordinate Si/Ge species investigated. Pentagonal shapes, with 5 surrounding atoms coloured green for Mg or purple for In/Tl, with a central brown atom for Si/Ge, connected to each periphery atom.

Figure 1: Structures for the global minima of the two planar pentacoordinate Si/Ge structures

Based on the precedence of B or Al atoms as ligands for stabilising planar hypercoordinate carbon atoms, the researchers first investigated alkaline earth atoms to stabilise the group 14 centres, looking at XM₅^2-structures (X = Si, Ge; M = Mg, Ca, Be). A local energy minimum and a planar, pentacoordinate D_5h geometry was only calculated for the triplet-state magnesium species (Figure 2), indicating that analogues of XMg₅^2- were suitable for further investigation.

The three possible lowest energy structures for XM5(2-). The left structure is pentagonal, with a central Si/Ge connected to each periphery atom. The middle structure shows the Si/Ge connected to 4 M atoms in a square shape, with the fifth M atom bridging above the top two M atoms in the square. The third structure on the right shows the Si/Ge atom connected to the 5 M atoms around it, but in an irregular, non-pentagonal shape, where the M atoms do not all connect outside the central Si/Ge atom.

Figure 2: Structures of XM52- (X = Si, Ge; M = Mg, Ca, Be), where Nimag refers to the numbers of imaginary frequencies [3A1 refers to the triplet state, 1A1 refers to the singlet state]

The researchers calculated the potential energy surfaces of both the singlet and triplet states of XMg₅^2-, optimising the lowest-lying structures. They found that the most energetically favourable isomers of both SiMg₅^2- and GeMg₅^2- were planar tetracoordinate in the singlet state, but there was only a very small energy range (0.4-1.5 kcal mol^-1) between these singlet ptX structures and the desirable ppX structure in the triplet state. The researchers therefore turned to substitution of one of the surrounding ‘ligand’ atoms for heavier group 13 elements, to build a suitable-sized cavity for planar pentacoordinate silicon or germanium. They investigated XMg₄Y^– structures (Y = Al-Tl) and found that a planar pentacoordinate structure was the lowest in energy for Y = In or Tl, with a more substantial jump to the next highest energy level structure (2.4-3.9 kcal mol^-1). They also investigated disubstituted systems, XMg₃Y₂, noting that only SiMg₃In₂had a ppX structure at the global energy minimum. They also found that the ppXs investigated all had 16 valence electrons, defying the 18-electron rule standard.

Overall, the researchers have theoretically predicted the first examples of thermodynamically and kinetically stable planar pentacoordinate silicon or germanium atoms. These structures combine both stabilising magnesium and larger group 13 element ‘ligands’, and are suitable candidates for future experimental detection, proving that silicon and germanium can too, break the rules of valency and tetrahedral coordination.

To find out more, please read:

Planar pentacoordinate silicon and germanium atoms

Meng-hui Wang, Xue Dong, Zhong-hua Cui, Mesías Orozco-Ic, Yi-hong Ding, Jorge Barroso* and Gabriel Merino

Chem. Commun., 2020, 56, 13772-13775

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Chemical Communications Blog

Congratulations to the 2021 Cram Lehn Pedersen Prize Winner: Amanda Hargrove

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One-dimensional carbon ladders

ChemComm Milestones – Thanthapatra (Valentine) Bunchuay

ChemComm Milestones – Hennie Valkenier

Breaking the rules of valency for silicon and germanium

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