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Coordinating nature and photochemistry to create hydrogen

28 Aug 2015

When we look to our future energy resources, the need to realise new means of renewable energy is immediately obvious. Much research is being carried out around the world into the development of systems that can generate energy – from H₂ to biofuels to solar fuels – all of which place great importance on high efficiency and sustainability.

Looking at the world around us for inspiration, the obvious candidate is the photosynthetic process, where visible light is employed to convert CO₂ and H₂O into chemical energy. This process involves the transport of electrons through a complex series of intricately aligned porphyrin-related and protein biomolecules. We can explore the development of a system that mimics the behaviour of natural systems, with respect to the relay of electrons along a series of molecules, or, alternatively, we can take the components in these systems and exploit their properties in combination with other electronically-active but non-natural molecules.

Upon photoexcitation of [Ru(bpy)3]2+, electron transfer through a ferredoxin scaffold to a cobaloxime catalyst facilitates the production of hydrogen. It is the latter approach which Lisa Utschig and her team from Argonne National Laboratory, near Chicago in the US, employed to generate a molecular system capable of photocatalysing the production of hydrogen. In their biohybrid system, the photosensitiser ruthenium(II) tris(bipyridine), ferredoxin (a water-soluble electron transfer protein), and cobaloxime (a cobalt(II)-based catalyst), were combined to generate a miniature reaction center that mimics those which occur in biological systems. However, the Utschig group’s system has a smaller molecular weight, which allows for characterisation of the electronic processes that occur in the system.

Lisa and her colleagues found that the presence of ferredoxin in the catalytic system acted as a scaffold to stabilise the charge-separated state necessary for electron transfer and the desired production of H_2.They also observed that the catalytic behaviour of the Ru(II)–Co(II) pair was only possible in the presence of ferredoxin, which acted to extend the lifetime of the otherwise transient Co(I), allowing the desired reaction to occur.

In order to fully understand and enhance the properties of the molecular systems developed to fulfil the increasing need for energy alternatives, we need to be able to probe the structure and processes that occur in the molecule; the use of smaller analogs to those that exist in nature offers a means by which to achieve this goal. The photoactivated catalyst discussed in this work is an important step forward in the development of an optimized system for use in solar fuel production.

Read this hot ChemComm article in full:
Aqueous light driven hydrogen production by a Ru–ferredoxin–Co biohybrid
S. R. Soltau, J. Niklas, P. D. Dahlberg, O. G. Poluektov, D. M. Tiede, K. L. Lulfort and L. M. Utschig
Chem. Commun., 2015, 51, 10628–10631
DOI: 10.1039/C5CC03006D

Biography

Anthea Blackburn is a guest web writer for Chemical Science. She hails originally from New Zealand, and is a recent graduate student of Northwestern University in the US, where she studied under the tutelage of Prof. Fraser Stoddart (a Scot. There, she exploited 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.

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Feihe Huang wins Cram Lehn Pedersen Prize 2015

23 Jun 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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Hierarchical 3D immunoassays – higher loading, lower fouling

08 May 2015

If you are producing an immunoassay there are two key parameters you need to understand and optimise: surface structure and surface chemistry. Get these two parameters right and you will optimise the sensitivity of your immunoassay.

Although there have been a multitude of 3D surface generation routes reported, they are generally complicated and require a lot of additional steps. Although these 3D surfaces lead to high probe loading levels they also often lead to high levels of non-specific protein absorption, undoing any good the surface structure would have led to.

Jinghua Yin and team from the State Key Laboratory of Polymer Physics and Chemistry at the Changchun Institute of Applied Chemistry have focussed on both properties to generate a much improved immunoassay.

Firstly they generated a 3D surface using UV irradiation of polystyrene spheres onto a substrate; they then grafted polymer brushes to the sphere surface. The polymer brushes not only further increased the surface area (more than doubling it from the bare sphere surface) but also acted as an anti-fouling agent, reducing the amount of non-specific binding observed by up to 90%.

Antibody loading on different surface types showing increasing loading levels

The commonality of the functional groups on the polymer brushes mean that any antibody can be attached to the prepared surface. To find out the details of how to make these surfaces and try them out on your own immunoassays, read the paper today!

To read the details, check out the ChemComm article in full:
Facile fabrication of microsphere-polymer brush hierarchically three-dimensional (3D) substrates for immunoassays
Jiao Ma, Shifang Luan, Lingjie Song, Shuaishuai Yuan, Shunjie Yan, Jing Jin and Jinghua Yin
Chem. Commun., 2015, 51, 6749-6752
DOI: 10.1039/C5CC01250C

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Rotaxane Pulley – To Me, To You

10 Apr 2015

Mechanically interlocked molecules have received ever increasing focus over the last number of years due to their potential to mimic the function of macroscopic devices in the molecular world.

Examples include molecular elevators and molecular muscles and with this Communication Zheng Meng and Chuan-Feng Chen of the CAS Key Laboratory of Molecular Recognition and Function at the Chinese Academy of Sciences in Beijing have added pulley-like shuttling motion to the toolkit.

Molecular pulley system powered by acid and base

Using their previously reported* triptycene-derived crown ether host and combining it with a linear guest with three dibenzylammonium and three N-methyltriazolium sites, they have made a molecular pulley system that mimics the plain rotary motion and linear translocation of full sized pulleys. The movement is powered by acid or base leading to one end of the cable-like guest moving towards the host while the other moves away (picture).

The researchers have not only added to the toolbox of molecular motion components but also provided new insights towards further developing molecular machines.

If you want to make your own molecular pulley read the article today!

To read the details, check out the ChemComm article in full – it’s free to access until 10th May:
A molecular pulley based on a triply interlocked [2]rotaxane
Zheng Meng and Chuan-Feng Chen
Chem. Commun., 2015, 51, Advance Article
DOI: 10.1039/C5CC01301A

*(a) C. F. Chen, Chem. Commun., 2011, 47, 1674–1688 RSC; (b) Y. Han, Z. Meng, Y. X. Ma and C. F. Chen, Acc. Chem. Res., 2014, 47, 2026–2040

**Access is free through a registered RSC account – click here to register

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A collection of papers in memory of Professor Robert Williams

02 Apr 2015

Professor Robert (Bob) Williams died this March at the age of 89. He was a true pioneer in the field of bio-inorganic chemistry – especially concerning the role of calcium as a biological messenger – and contributed substantially to our understanding of the evolution of life. Professor Williams was often considered as one of the first people to start thinking about metallomics as a field, and will be greatly missed amongst his peers.

In memory of Professor Williams’ huge contribution to the field, we have collated a number of his publications across Metallomics, Dalton Transactions and ChemComm below. We hope you enjoy revisiting some of his exceptional work.

Copper proteomes, phylogenetics and evolution, L. Decaria, I. Bertini, R.J.P. Williams, Metallomics, 2011, 56–60

Zinc proteomes, phylogenetics and evolution, L. Decaria, I. Bertini, R.J.P. Williams, Metallomics, 2010, 706–709

A chemical systems approach to evolution, R.J.P. Williams, Dalton Transactions, 2007, 991–1001

Metallo-enzyme catalysis, R.J.P. Williams, Chemical Communications, 2003, 1109–1113

The chemical elements of life, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1991, 539–546

Temperature study of the solution conformations of aqueous lanthanide(III) complexes containing monodentate ligands, A.L. Du Preez, S. Naidoo, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1988, 2315–2321

A proton NMR study of some CoII complexes containing the N-hexadecyl-iminodiacetate ligand, C.J. Rix, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1986, 203–205

Solution conformation of aqueous lanthanide(III)-antipyrine complexes, A.L. Du Preez, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1986, 1425–1429

Precipitation within unilamellar vesicles. Part 1. Studies of silver(I) oxide formation, S. Mann, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1983, 311–316

Precipitation within unilamellar vesicles. Part 2. Membrane control of ion transport, S. Mann, M.J. Kime, R.G. Ratcliffe, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1983, 771–774

The characterisation of the nature of silica in biological systems, S. Mann, C.C. Perry, R.J.P. Williams, C.A. Fyfe, G.C. Gobbi, G.J. Kennedy, Journal of the Chemical Society, Chemical Communications, 1983, 168–170

New organo-metallic reagents for electron microscopy, S. Mann, R.J.P. Williams, P.R. Sethuraman, M.T. Pope, Journal of the Chemical Society, Chemical Communications, 1981, 1083–1084

Solid state phosphorus NMR spectroscopy of minerals and soils, R.J.P. Williams, R.G.F. Giles, A.M. Posner, Journal of the Chemical Society, Chemical Communications, 1981, 1051–1052

Electron relaxation rates of lanthanide aquo-cations, B.M. Alsaadi, F.J.C. Rossotti, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1980, 2147–2150

Hydration of complexone complexes of lanthanide cations, B.M. Alsaadi, F.J.C. Rossotti, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1980, 2151–2154

Preparation of Ag2O crystallites within phospholipid vesicles and their use in nucleation studies, J.L. Hutchison, S. Mann, A.J. Skarnulis, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1980, 634–635

Studies of lanthanide (III) dipicolinate complexes in aqueous solution. Part 2. Hydration, B.M. Alsaadi, F.J.C. Rossotti, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1980, 813–816

Studies of lanthanide(III) pyridine-2,6-dicarboxylate complexes in aqueous solution. Part 1. Structures and 1H nuclear magnetic resonance spectra, B.M. Alsaadi, F.J.C. Rossotti, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1980, 597–602

Location of biological compartments by high resolution NMR spectroscopy and electron microscopy using magnetite-containing vesicles, S. Mann, A.J. Skarnulis, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1979, 1067–1068

Mapping organic molecules in biological space by high resolution NMR spectroscopy and electron microscopy, A.J. Skarnulis, P.J. Strong, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1978, 1030–1032

An investigation of some potential uses of the gadolinium(III) ion as a structural probe, E.C.N.F. Geraldes, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1977, 1721–1726

Structure of lanthanide(III) mono- and bis-dipicolinates in solution, B.M. Alsaadi, F.J.C. Rossotti, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1977, 527–529

Assignment of the NMR spectrum of iron(III) protoporphyrin IX dicyanide using paramagnetic shift and broadening probes, J.G. Brassington, R.J.P. Williams, P.E. Wright, Journal of the Chemical Society, Chemical Communications, 1975, 338–340

Conformational studies of peroxidase-substrate complexes. Structure of the indolepropionic acid-horseradish peroxidase complex, P.S. Burns, R.J.P. Williams, P.E. Wright, Journal of the Chemical Society, Chemical Communications, 1975, 795–796

The temperature dependence of some physical properties of cobinamides and cobalamins, S.A. Cockle, O.D. Hensens, H.A.O. Hill, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1975, 2633–2634

Conformational studies of lanthanide complexes with carboxylate ligands, B.A. Levine, J.M. Thornton, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1974, 669–670

Ethylenediaminetetra-acetato-lanthanate(III), -praesodimate(III), -europate(III), and -gadolinate(III) complexes as nuclear magnetic resonance probes of the molecular conformations of adenosine 5′- monophosphate and cytidine 5′-monophosphate in solution, C.M. Dobson, R.J.P. Williams, A.V. Xavier, Journal of the Chemical Society, Dalton Transactions, 1974, 1762–1764

Intramolecular nuclear Overhauser effects in proton magnetic resonance spectra of proteins, I.D. Campbell, C.M. Dobson, R.J.P. Williams, Journal of the Chemical Society, Chemical Communications, 1974, 888–889

Lanthanoid(III) cations as nuclear magnetic resonance conformational probes: Studies on cytidine 5′-monophosphate at pH 2, C.D. Barry, C.M. Dobson, R.J.P. Williams, A.V. Xavier, Journal of the Chemical Society, Dalton Transactions, 1974, 1765-1769

Nuclear magnetic resonance spectra of dimeric cupric compounds, W. Byers, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1973, 555–560

Separation of contact and pseudo-contact contributions to shifts induced by lanthanide(III) ions in nuclear magnetic resonance spectra, C.M. Dobson, R.J.P. Williams, A.V. Xavier, Journal of the Chemical Society, Dalton Transactions, 1973, 2662–2664

The effect of 1,3,5-trinitrobenzene on 1H nuclear magnetic resonance and electron paramagnetic resonance spectra of some cobalt(II) porphyrins, H.A.O. Hill, P.J. Sadler, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1973, 1663–1667

Origin of lanthanide nuclear magnetic resonance shifts and their uses, B. Bleaney, C.M. Dobson, B.A. Levine, R.B. Martin, R.J.P. Williams, A.V. Xavier, Journal of the Chemical Society, Chemical Communications, 1972, 791b–793

The chemistry of vitamin B12. Part XVI. Binding of thiols to the cobalt(II) corrins, S. Cockle, H.A.O. Hill, S. Ridsdale, R.J.P. Williams, Journal of the Chemical Society, Dalton Transactions, 1972, 297–302

A method of assigning 13C nuclear magnetic resonance spectra using europium(III) ion-induced pseudocontact shifts and C-H heteronuclear spin decoupling techniques, B. Birdsall, J. Feeney, J.A. Glasel, R.J.P. Williams, A.V. Xavier, Journal of the Chemical Society D: Chemical Communications, 1971, 1473–1474

Methylation by methyl vitamin B12, G. Agnes, S. Bendle, H.A.O. Hill, F.R. Williams, R.J.P. Williams, Journal of the Chemical Society D: Chemical Communications, 1971, 850–851

Kinetics of substitution of co-ordinated carbanions in cobalt(III) corrinoids, H.A.O. Hill, J.M. Pratt, S. Ridsdale, F.R. Williams, R.J.P. Williams, Journal of the Chemical Society D: Chemical Communications, 1970, 341

Thallium(I) as a potassium probe in biological systems, J.P. Manners, K.G. Morallee, R.J.P. Williams, Journal of the Chemical Society D: Chemical Communications, 1970, 965–966

The lanthanide cations as nuclear magnetic resonance probes of biological systems, K.G. Morallee, E. Nieboer, F.J.C. Rossotti, R.J.P. Williams, A.V. Xavier, R.A. Dwek, Journal of the Chemical Society D: Chemical Communications, 1970, 1132–1133

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Opening the door to poly(ionic liquid)s with enhanced properties

06 Mar 2015

Poly(ionic liquid)s, or PILs, are polyelectrolytes whose potential uses are being investigated for a variety of technologies, such as batteries, membranes, solar cells and switchable surfaces. In this ChemComm communication, Professor Eric Drockenmuller and co-workers at the Université de Lyon, University of Liège and the Institut Universitaire de France describe a new family of PILs based on poly(vinyl ester 1,2,3-triazolium)s, which should give rise to new properties and application possibilities.

The materials are prepared from a multistep route making use of `click chemistry´(copper(I) catalysed azide alkyne Huisgen cycloaddition reaction), palladium catalyzed vinyl group exchange, and cobalt mediated radical polymerisation. This route yields a neutral polymer, which is transformed into the poly(ionic liquid) using N-methyl bis[(trifluoromethyl)sulfonyl]imide. This useful reagent alkylates the triazole group present, and delivers the bis[(trifluoromethyl)sulfonyl]imide counterion in one step.

Synthetic route used to yield new poly(vinyl-ester 1,2,3-triazolium)s

The ionic conductivity for the PIL reported is slightly lower than for other types of PIL. To tune this property, a variety of alkynes and azides are being tested in the ring forming step of the reaction, which will result in different substituents on the triazolium ring and on the spacer group between the polymer backbone and triazolium ring. Changes in thermal properties in the the neutral precursor-to-PIL stage of the reaction were measured using broadband dielectric spectroscopy. Significant changes in solubility, and a 9⁰C rise in glass transition temperature to -16⁰C, were observed.

The molecular variety introduced by this new synthetic approach offers large scope for fine tuning the electronic and mechanical material properties of these polyelectrolytes, further enabling their use in important technological applications.

Read this Chemical Communication today – it’s free to access until 3rd April*:

Poly(vinyl ester 1,2,3-triazolium)s: a new member of the poly(ionic liquid)s family
M. M. Obadia, G. Colliat-Dangus, A. Debuigne, A. Serghei, C. Detrembleurb and E. Drockenmuller
DOI: 10.1039/c4cc08847f

*Access is free through a registered RSC account – click here to register

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Biochemical Logic Systems – closed-loop “Sense/Act” operations

26 Feb 2015

When research in a particular area reaches saturation point, the question of future applications becomes critically important. This recent Feature Article in ChemComm considers molecular logic gates, which have not yet achieved pure computational applications (with their hoped for advantages) due to limitations caused by noise build-up and cross-talk between various biomolecular elements. Thus they are unable to compete with electronic computing devices. The authors ask the question: what potential applications are there that justify the continued research in this field?

Evgeny Katz from the Department of Chemistry and Biomolecular Science at Clarkson University with Sergiy Minko from the Nanostructured Materials Lab at the University of Georgia lead the reader through a short overview of potential answers. These include “smart” switchable membranes, electrodes, biofuel cells and drug-releasing systems.

The use of biochemical data processing to produce a yes/no answer provides the opportunity for direct coupling with signal-responsive materials to produce a closed-loop “sense/act” operation. This ability has the potential to transform the field of biosensors and bioactuators.

(A) A biocatalytic cascade activated by enzyme–substrate inputs and resulting in the in situ produced pH changes. (B) The logic circuitry equivalent to the biocatalytic cascade. (C) pH-switchable electrode interface modified with a polymeric brush.

The authors could be considered brave to ask the question of such a popular focus of research, but this article provides an opportunity for reflection and thought about what biochemical computing research can uniquely achieve. Having read this article I was left with a sense of excitement at the specific in vivo sensing possibilities that biochemical computing provides. To find out if you think the opportunities are exciting too, read the article today!

To read the details, check out the ChemComm article in full:
Enzyme-based logic systems interfaced with signal-responsive materials and electrodes
Evgeny Katz and Sergiy Minko
Chem. Commun., 2015, 51, Advance Article
DOI: 10.1039/C4CC09851J

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Accessing Chiral Space with Visible Light

03 Feb 2015

Researchers have made tremendous efforts to unlock stereoselective, catalytic organic transformations. In this recent ChemComm Feature Article, Professor Eric Meggers, one of the pioneers in the field of photoredox catalysis, provides a comprehensive review of the recent advances in asymmetric catalysis driven by visible light.

Asymmetric catalysis has been one of the most attractive yet challenging areas of organic chemistry for the synthesis of unique, biologically active natural products such as Taxol, Rapamycin, or Vinblastine that possess numerous stereocenters.

C4CC09268F ga Recently, visible light, a sustainable and affordable energy resource, gained substantial interest with its capability to selectively access chiral molecules from prochiral substrates without undesirable by-products. Transformations including aldehyde α-functionalization and [2+2] cycloadditions demonstrate the potential of visible light in the presence of a photosensitizer.

These photosensitizers are typically ruthenium or iridium complexes that can facilitate electron/energy transfer upon photoinduction. In most cases, a photoredox catalyst has to be coupled with a chiral co-catalyst to introduce stereocenters in the products.

Notable advances in the Meggers, Melchiorre, and MacMillan research groups have recently demonstrated that photoactivation can be achieved with a single chiral photosensitizer to provide products of high enantiomeric excess and good yield.

This inspirational review was just published in Chemical Communications as a Feature Article. I recommend reading “Asymmetric catalysis activated by visible light” (DOI: 10.1039/c4cc09268f) by Professor Eric Meggers to learn more about the recent advances with mechanistic details and his forecast for one of the rapidly-growing research topics in organic chemistry.

This article is free to access until 17th March.* Download it here:
Asymmetric catalysis activated by visible light
Eric Meggers �
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC09268F, Feature Article

Dr. Tezcan Guney is a guest web writer for Chemical Communications. Dr. Guney received his Ph.D. from the Department of Chemistry at Iowa State University with Prof. George Kraus, where he focused on the synthesis of biologically active polycyclic natural products and multifunctional imaging probes. Currently, he is a postdoctoral research scholar at the Memorial Sloan-Kettering Cancer Center in New York with Prof. Derek Tan, contributing to the efforts to access biologically active small molecules using the diversity-oriented synthetic approach.

*Access is free through a registered RSC account

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Capturing C60 in a Crystalline Copolymer Chain

12 Nov 2014

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, Davis – Marilyn 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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Bubble power: Driving self-propelled machines with acetylene bubbles

04 Nov 2014

Self-propelled micro/nanomachines were once the thing of science-fiction, but as so often is the case, fiction has become reality in recent years. Such devices could in the future find uses in environmental remediation and biomedical applications. Researchers around the world have been making progress on designing these machines, and it is a novel fuel-free autonomous self-propelled motor which is the focus of this Chemical Communication by Martin Pumera and team from the School of Physical and Mathematical Sciences at Nanyang Technological University.

Rather than focus on oxygen bubble propulsion, which often requires the use of high levels of toxic hydrogen peroxide, they have developed an acetylene bubble based motor. To achieve this they utilised the reaction of water and calcium carbide, which produces acetylene and calcium hydroxide. This approach makes use of the water that will be found in the most common application environments, but does not require reactive metals such as magnesium and aluminium. The work expands the scope of bubble-propulsion beyond hydrogen and oxygen and gives designers of micro/nanomachines greater power unit choices in their designs.

Acetylene bubble powered motor in water.

The most important part of the research reported in this Communication is the optimisation of an encapsulation layer around the calcium carbide to control the reaction. However, to find out what this layer is made of and how to prepare it you will have to read the article today.

To read the details, check out the Chem Comm article in full:

Acetylene bubble-powered autonomous capsules: towards in situ fuel
James Guo Sheng Moo, Hong Wang and Martin Pumera
Chem. Commun., 2014, 50, Advance Article
DOI: 10.1039/C4CC07218A

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