Archive for the ‘Supramolecular’ Category

ChemComm Poster Prize winner for the 2nd Early Career Researchers Meeting of the RSC–Macrocyclic and Supramolecular Chemistry Group

Dr Guillaume De Bo (left) presenting the ChemComm prize to Alexander Elmi (right).

The 2nd Early Career Researchers Meeting of the RSC-Macrocyclic and Supramolecular Chemistry (RSC-MASC) Group took place on 27th July 2018 at the University of Manchester, UK. This one-day symposium was organised by Dr. Guillaume De Bo (University of Manchester) and was attended by PhD students and post-doctoral researchers within the supramolecular field.

The meeting consisted of fifteen selected talks from submitted abstracts, and all attendees were invited to present a poster. The day ended with a plenary lecture by Professor Anthony Davis (University of Bristol) on ‘Biomimetic Carbohydrate Recognition:  The Host-Guest Chemistry of Carbohydrates in Water’.

ChemComm was proud to sponsor this successful symposium. Alexander Elmi (University of Edinburgh) received the ChemComm poster prize for his poster entitledUnderstanding Aromatic Stacking Interactions In Solution’.

 

Congratulations Alexander from everyone at ChemComm!

 

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ChemComm poster prize winner at the 16th Symposium for Host-Guest and Supramolecular Chemistry

The 16th Symposium for Host-Guest and Supramolecular Chemistry was held on 2 – 3 June 2018 at the Tokyo University of Science in Japan.

This annual symposium covers all aspects of the chemical sciences related to molecular recognition and supramolecular chemistry, including the discussion of topics around intermolecular interactions. The event included a special lecture by Dr Shigeki Sasaki and invited lectures by Dr Takashi Hayashi and Dr Katsuhiko Ariga.

ChemComm is delighted to announce that the ChemComm poster prize was awarded to Hiroshi Koganezawa from the Tokyo University of Science for a poster entitled ‘Synthesis of [2]Rotaxanes with Spirofluorene and Pyrrole Moieties’.

Well done Hiroshi from everyone at ChemComm!

 

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Come for the colour changing crystals, stay for the science

Synthesis of copper bimetallic complexes from imidazolyl ligands, and the solvatochromic materials formed upon crystallization and solvent guest-exchange. The solvatochromic behaviour was quantified with visible-region diffuse reflectance spectra.

Synthesis of copper bimetallic complexes from imidazolyl ligands, and the solvatochromic materials formed upon crystallization and solvent guest-exchange. The solvatochromic behaviour was quantified with visible-region diffuse reflectance spectra.

During the first inorganic chemistry course I took during my undergraduate degree, our professor started the class by passing around some mineral samples, promising us that if we pursued the chemistry of metals we could work with beautifully coloured crystals every day. At the time, colour seemed like such a trite detail amongst the complexity of the subject. Why would you choose a field of study based on something so simple? Well, after a PhD dominated by pale yellow oils, I think I get it now.

Nikolayenko and Barbour at the University of Stellenbosch in South Africa bring us colour! The authors synthesised organometallic copper complexes, which crystallise to form porous single crystals that drastically change colour upon absorption of various solvents. The authors investigated the solvatochromic mechanism using X-ray crystallography, EPR, UV-visible spectroscopy and DFT calculations. Solvatochromic materials are not just made to look pretty; they have potential to be used as sensitive, selective and recyclable sensors to detect solvent vapours with useful applications in industrial process risk management, chemical threat detection and environmental monitoring.

The researchers synthesised a series of complexes comprised of a bidentate ligand with 2-methylimidazolyl groups coordinated to copper(II) ions. The complexes stack to form channels in the crystal, capable of trapping solvent molecules to give different coloured crystals: DMSO and THF-containing crystals are green (λmax = 574 nm and 540 nm, respectively), those containing acetonitrile are red (λmax = 624 nm), and crystals trapping acetone, ether and pentane are yellow (λmax = 588), orange (λmax = 598 nm) and red/brown (λmax = 592 nm), respectively.

The authors revealed a correlation between the size of the solvent guest, coordination geometry of the copper complex, and the ligand field splitting. Small guests such as acetonitrile minimally perturb the metallocyclic framework, preserving a rhombic ligand field geometry (large δxy of g values in the EPR spectrum), small ligand d-orbital splitting and red-shifted optical spectra. Large guests such as THF have the opposite effect, giving ligand field geometries approaching tetragonal (small δxy), large ligand field d-orbital splitting and blue-shifted optical spectra.

By delving into the complexity beneath a seemingly simple phenomenon, Nikolayenko, Barbour and their co-workers have shown using a series of single-crystal complexes that there is nothing simple about colour (and nothing trite about detail).

To find out more please read:

Supramolecular solvatochromism: mechanistic insight from crystallography, spectroscopy, and theory

Varvara I. Nikolayenko, Lisa M. van Wyk, Orde Q. Munro, Leonard J. Barbour.
Chem. Commun., 2018, Advance Article
DOI: 10.1039/c8cc02197j

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

 

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An Industrial Revolution on the Nanoscale

“What are the possibilities of small but movable machines? They may or may not be useful, but they surely would be fun to make”. In December 1959 Richard Feynman addressed the annual meeting of the American Physical Society at Caltech with a talk entitled ‘There’s Plenty of Room at the Bottom’, imploring the scientific community to start thinking small, like ‘entire 24 volumes of the Encyclopaedia Britannica on the head of a pin’ kind of small. Many quote this lecture as when the notion of nanomachines first entered the scientific sphere – with talk of miniature cars, injectable molecular ‘surgeons’ and machines that place atoms side by side to synthesize any molecule imaginable. The lecture reads like the description of the futuristic setting in ‘Back to the Future’, an exploration of possibilities at a time when we fundamentally lacked the tools to make them a reality.

As in ‘Back to the Future’, which predated yet predicted the emergence of mobile-banking technology, video calling and personal drones, Richard Feynman’s plea for scientists to prepare molecular-scale machines has also become a reality, and for their successes in this field Jean-Pierre Sauvage, Sir Fraser Stoddart and Ben Feringa were jointly awarded the Nobel Prize in Chemistry in 2016.

A group of researchers based in London and Singapore have written a feature article introducing both the foundational work in this field and state-of-the-art examples. Nanomachines are single molecules or molecular assemblies on the nanoscale (this review defines a 1 – 100 nm scope) that have the ability to perform ‘useful work’ upon application of an external energy source. To extract work (often in the form of controlled mechanical movement) molecular machines are designed to operate at a thermodynamically far-from-equilibrium state, maintained by an energy input, with movement occurring as the system relaxes towards equilibrium. At the synthetic level, molecules are designed with components which have restricted translational and rotational movements with respect to each other, and the ability to control these movements is key to obtaining the desired function.

A catalytically active rotaxane synthesised by Nolte and co-workers acts as a tiny epoxidising machine , moving along a polybutadiene polymer

The catalytically active rotaxane synthesised by Nolte and co-workers acts as a tiny epoxidising machine, moving along a polybutadiene polymer

One of the first advances towards the synthesis of nanomachines was by the research group of Jean-Pierre Sauvage, who achieved the templated synthesis of catenanes; structures with two circular molecules that are interlocked like two links in a chain. It was subsequently shown that a catenane motor could be prepared, with one ring rotating with respect to the other in a controlled manner. Fraser Stoddart further contributed to the field with ‘rotaxanes’, composite molecules comprising a ring threaded onto an axle. Nanomachines based on rotaxanes have been developed and include switches, shuttles and ‘molecular elevators’. A state-of-the-art example of a catalytically active rotaxane synthesised by Nolte and co-workers in 2003 demonstrates the potential of nanomachines to revolutionise organic synthesis. The rotaxane is constructed with a magnesium-bound porphyrin, which threads onto a polybutadiene polymer (300 kDa, 98% cis) and catalyses the epoxidation of the double bonds (turnover number: 140, cis/trans ratio of the polyepoxide: 1:4).

Ben Feringa's electric nano-car, a single molecule with four fluorene 'wheels' capable of driving across a copper surface

Ben Feringa’s electric nano-car, a single molecule with four fluorene ‘wheels’ capable of driving across a copper surface

In 2011 Ben Feringa and co-workers synthesized the worlds tiniest electric car using the same design principles they had used to create a spinning motor in 1999. The car is a single molecule with the ability to propel itself across a crystalline copper surface upon activation by a voltage pulse, with 10 pulses moving the car 6 nm across the surface. The car itself is comprised of a central diyne strut bonded at each end to carbazole ‘axles’. Each axle is bound through alkenes to two fluorene ‘wheels’. The key design elements are the alkenes and two chiral methyl substituents on each axle which forces each wheel to twist out of the plane. For one wheel rotation: an electronic excitation induces transcis isomerisation of the alkene causing a quarter turn of the wheel such that it sits adjacent to the methyl group. Next, a vibrational excitation induces helical inversion, allowing the wheel to push past the methyl group another quarter turn. Another isomerisation and helical inversion completes a full rotation. Research achievements like these demonstrate mechanical work on the nanoscale, with the vision of achieving movement on the macroscale via synchronised motion.

These examples represent a small subset of those discussed in the feature article review, which not only spans the current scope of molecular-scale machines, but reviews the design principles guiding their development and the possibilities nanomachines represent in the future of scientific research.

To find out more please read: 

Artificial molecular and nanostructures for advanced nanomachinery

Elizabeth Ellis, Suresh Moorthy, Weng-I Katherine Chio and Tung-Chun Lee.
Chem. Commun., 2018, Advance Article
DOI: 10.1039/c7cc09133h

About the author:

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

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Congratulations to the 2018 Cram Lehn Pedersen Prize winner: Rafal Klajn

We are proud to announce that Dr. Rafal Klajn, at the Weizmann Institute of Science in Israel, as 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 Rafal, a well-deserved winner!

 

Dr. Rafal Klajn

Rafal is an Associate Professor at the Weizmann Institute of Science and will receive the award during the 2018 International Symposium on Macrocyclic and Supramolecular Chemistry (ISMSC).

This annual conference consists of sessions of invited lectures that focus upon a single topic area, award lectures and poster sessions. This year, the conference will also feature evening sessions on supramolecular chemistry with keynote speakers as well as an exciting series of Nobel Lectures on the final day!

Find out more and register here.

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Cram Lehn Pedersen Prize 2017 – call for nominations

ISMSC-ISACS 2017, 2-6 July 2017, Cambridge, UK

The International Committee of the International Symposium on Macrocyclic and Supramolecular Chemistry is pleased to invite nominations for the Cram Lehn Pedersen Prize for young supramolecular chemists.

The Cram Lehn Pedersen Prize, named in honour of the winners of the 1987 Nobel Prize in Chemistry, recognises significant original and independent work in supramolecular chemistry.

Previous winners include Ivan Aprahamian, Feihe Huang, Oren Schermann, Tomoki Ogoshi, Jonathan Nitschke, and Amar Flood.

Those who are within 10 years of receiving their PhD on 31st December 2016 are eligible for the 2017 award. The winner will receive a prize of £2000 and free registration for the ISMSC-ISACS meeting in Cambridge, UK. In addition to giving a lecture at ISMSC-ISACS, a short lecture tour will be organised after the meeting in consultation with the Editor of Chemical Communications, the sponsor of the award.

Nomination Details:

You may nominate yourself or someone else. Please send your CV, list of publications (divided into publications from your PhD and post-doc, and those from your independent work), and if desired, a letter of support, or these materials for someone you wish to nominate, to Prof. Roger Harrison (ISMSC Secretary) at rgharris@chem.byu.edu by 31st December 2016.

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Ivan Aprahamian wins Cram Lehn Pedersen Prize

Photograph of Professor Ivan AprahamianThe International Committee of the International Symposium on Macrocyclic and Supramolecular Chemistry is delighted to announce that the 2016 Cram Lehn Pedersen Prize, given annually to an outstanding early-career supramolecular chemist, has been awarded to Professor Ivan Aprahamian, Dartmouth College, USA for his exciting research on molecular switches – congratulations!

As part of the Prize, Prof. Aprahamian will give a lecture at the 11th International Symposium on Macrocyclic and Supramolecular Chemistry meeting in Seoul, Korea which takes place from 10–14 July 2016.

Photograph of Dr Jeanne AndresDr Jeanne Andres (Deputy Editor of ChemComm) will be attending the event and will present the award in person. She would love to hear about your research and meet with our readers, authors and referees. Please do get in touch with Jeanne if you would like to arrange a meeting in advance.

We are also delighted to announce that the International Symposium on Macrocyclic and Supramolecular Chemistry in 2017 will be held in conjuction with ISACS: Challenges in Organic Materials & Supramolecular Chemistry.

Our keynote speakers will be:

  • François Diederich (ETH Zurich, Switzerland)
  • David Leigh (The University of Manchester, UK)
  • Jeffrey Long (University of California, Berkeley, USA)
  • Vivian Yam (University of Hong Kong, Hong Kong)
  • Xi Zhang (Tsinghua University, China)

Full details of all the confirmed speakers may be found on the event website.

We hope you can join us in Cambridge, UK – save the dates 2–6 July 2017!

While you are waiting you might like to check out some of our recent themed collections of articles in the area of supramolecular chemistry – Enjoy!

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Nominate now for the 2016 Cram Lehn Pedersen Prize in Supramolecular Chemistry

The International Committee of the International Symposium on Macrocyclic and Supramolecular Chemistry is pleased to invite nominations for the Cram Lehn Pedersen Prize for young supramolecular chemists.

The Cram Lehn Pedersen Prize, named in honour of the winners of the 1987 Nobel Prize in Chemistry, recognises significant original and independent work in supramolecular chemistry.

Previous winners include Feihe Huang, Oren Schermann, Tomoki Ogoshi, Jonathan Nitschke, and Amar Flood.

Those who are within 10 years of receiving their PhD on 31st December 2015 are eligible for the 2016 award. The winner will receive a prize of £2000 and free registration for the ISMSC meeting in Seoul, Korea. In addition to giving a lecture at ISMSC, a short lecture tour will be organised after the meeting in consultation with the Editor of Chemical Communications, the sponsor of the award.

Nomination Details:

You may nominate yourself or someone else. Please send your CV, list of publications (divided into publications from your PhD and post-doc, and those from your independent work), and if desired, a letter of support, or these materials for someone you wish to nominate, to Prof. Roger Harrison (ISMSC Secretary) at rgharris@chem.byu.edu by 31st January 2016.

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Feihe Huang wins Cram Lehn Pedersen Prize 2015

Congratulations to Prof Feihe Huang from the State Key Laboratory of Chemical Engineering at Zhejiang University, China, winner of the 2014 Cram Lehn Pedersen Prize in Supramolecular Chemistry.

The prize, sponsored by ChemComm, is organised by the committee of the International Symposium on Macrocyclic and Supramolecular Chemistry and is awarded each year to a young supramolecular chemist.

The Cram Lehn Pedersen Prize is named in honour of the winners of the 1987 Nobel Prize in Chemistry and recognises significant original and independent work in supramolecular chemistry. Previous winners include Oren Schermann, Tomoki Ogoshi, and Jonathan Nitschke.

Feihe will receive £2000, free registration for the ISMSC meeting in Strasbourg, France, and the opportunity to give a lecture at the ISMSC. He is also giving two additional lectures as part of his prize in Germany, at the Max Planck Institute of Colloids and Interfaces and the Free University of Berlin.

Dr May Copsey, Executive Editor of the journal, will be also attending this conference to personally award Feihe with the lectureship. She hopes to meet many ChemComm readers and authors there. Please do let her know if you will be there too!

“Professor Feihe Huang follows in the tradition of other winners and is an excellent supramolecular scientist. He has published over 100 articles as an independent researcher, in top tear journals such as ChemComm,” says Professor Roger Harrison, Associate Professor at Brigham Young University and Secretary of the ISMSC International Scientific Committee.  He adds, “He has set himself apart from other chemists by investigating supramolecular polymers and learning how to control their properties.”


Find out more about Feihe Huang by reading his recent research in ChemComm:

Prof Feihe Huang, Winner of the Cram Lehn Pedersen Prize 2015

A water-soluble biphen[3]arene: synthesis, host–guest complexation, and application in controllable self-assembly and controlled release
Jiong Zhou, Guocan Yu, Li Shao, Bin Hua and Feihe Huang
Chem. Commun., 2015, 51, 4188-4191
DOI: 10.1039/C5CC00225G, Communication

Reversible formation of a poly[3]rotaxane based on photo dimerization of an anthracene-capped [3]rotaxane
Peifa Wei, Xuzhou Yan and Feihe Huang
Chem. Commun., 2014, 50, 14105-14108
DOI: 10.1039/C4CC07044E, Communication

A CO2-responsive pillar[5]arene: synthesis and self-assembly in water
Kecheng Jie, Yong Yao, Xiaodong Chi and Feihe Huang
Chem. Commun., 2014, 50, 5503-5505
DOI: 10.1039/C4CC01704H, Communication

Host–guest complexation induced emission: a pillar[6]arene-based complex with intense fluorescence in dilute solution
Pi Wang, Xuzhou Yan and Feihe Huang
Chem. Commun., 2014, 50, 5017-5019
DOI: 10.1039/C4CC01560F, Communication

We invite you to submit your next communication article to ChemComm!

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Capturing C60 in a Crystalline Copolymer Chain

Since its structural realisation in 1985, C60 has garnered much attention in the chemical world for not only its spherical shape, but also its stability, electronic properties and the ability to do chemistry on its surface.

One such avenue that has proven popular in recent times is the incorporation of C60 into one-, two- and three-dimensional arrays, either covalently or non-covalently, in attempts to control the distribution of the molecules in the solid- or solution-phase.  One problem that arises in the synthesis of these extended frameworks, however, is that there often a large amount of disorder and void space in the structure, so it can be difficult to ascertain with much degree of certainty how these C60 molecules are oriented. This uncertainty can consequentially result in the properties and behaviours of the new materials remaining unidentified.

Now, researchers from the University of California, DavisMarilyn Olmstead and Alan Balch – have shown that coordination chemistry can be used to not only generate polymers that covalently link molecules of functionalised C60 in such a manner that can they can be studied crystallographically, but also that these polymers can be used to capture free C60 and C70.

Initially, polymers of C60 were synthesised through the mono-functionalisation of C60 with a piperazyl group, which, on account of its two tertiary amines, can coordinate in a linear fashion with transition metal ions, in this case rhodium(II) acetate. Upon the combination of these two components, a linear one-dimensional polymer was formed, in which it could be seen crystallographically that the C60 moieties were positioned on alternating sides of the polymer chain. These polymer chains were further found to extend into two dimensions through the interdigitation of neighbouring chains in a zipper-like fashion. C60-Rh(II) polymers can capture free C60

Perhaps more interestingly is that when these polymer chains were synthesised in the presence of either C60 or C70, free molecules of C60 or C70 were seen to occupy the void spaces between the C60 molecules of the polymer. Additionally, if a mixture of C60 and C70 was present in the polymer synthesis, it was observed that only C60 was captured by the polymer, most likely as a result of a better geometric match between the polymer and the spherical C60 in preference to the more elongated shape of C70.

This work elegantly demonstrates the generation of not only a self-assembling C60-containing polymer that can be characterised structurally in the solid state, but of one  that can entrap free molecules of C60 selectively over molecules of C70. Based on the properties of free C60 and transition metal complexes, the electronic and chromophoric properties of such a crystalline system could also be expected to offer some noteworthy results.

Read this HOT ChemComm article in full!

Zipping up fullerenes into polymers using rhodium(II) acetate dimer and N(CH2CH2)2NC60 as building blocks
Amineh Aghabali, Marilyn M. Olmstead and Alan L. Balch
Chem. Commun., 2014, Advance Article.
DOI: 10.1039/C4CC06995A

Biography

Anthea Blackburn is a guest web writer for Chemical Communications. Anthea is a graduate student hailing from New Zealand, studying at Northwestern University in the US under the tutelage of Prof. Fraser Stoddart (a Scot), where she is exploiting supramolecular chemistry to develop multidimensional systems and study the emergent properties that arise in these superstructures. When time and money allow, she is ambitiously attempting to visit all 50 US states before graduation.

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