The approaches developed previously to mimic chlorosomal assembly and function (with potential applications that include, for instance, the creation of photosynthesis-inspired solar cells) rely on (i) modification of naturally occurring tetrapyrrole macrocycles and (ii) synthesis and derivatization of porphyrins. In this NJC paper, researchers from Raleigh (North Carolina State University), St. Louis (Washington University), and Riverside (University of California) propose a third approach with the design and preparation of hydroporphyrins. Altogether, 30 new macrocycles were successfully synthesized, characterized and studied. The authors claim that this de novo strategy allows a fine tuning of the steric and electronic characteristics of the synthetic bacteriochlorophyll mimics.

“De novo synthesis and properties of analogues of the self-assembling chlorosomal bacteriochlorophylls” Olga Mass, Dinesh R. Pandithavidana, Marcin Ptaszek, Koraliz Santiago, Joseph W. Springer, Jieying Jiao, Qun Tang, Christine Kirmaier, David F. Bocian, Dewey Holten and Jonathan S. Lindsey New J. Chem., 2011, Advance Article. DOI: 10.1039/C1NJ20611G

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Scientists in China have designed and synthesized copolymer as the host and adamantyl fullerene as the guest to construct a host-guest supramolecular complex

Their work shows that the morphology of assemblies formed by the supramolecular complex can alter reversibly from vesicles to nano-spheres by the change of temperature in aqueous solution.

Due to the C60 moiety, the supramolecular complex shows excellent ability to scavenge hydroxyl radicals of biological system.

Thus, the combination of these two effects leads to the possibility of modulating the antioxidative properties of the supramolecular complex via the temperature.

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Self-assembled nanostructures from C₆₀-containing supramolecular complex: its stimuli-responsive reversible transition and biological antioxidative capacity

Haoyu Wang, Liang Wang, Xiaoguang Wang, Jiayun Xu, Quan Luo and Junqiu Liu New J. Chem., 2011, Advance Article DOI: 10.1039/C1NJ20568D, Paper

In this NJC paper, Siden Top and co-workers (Ecole Nationale Supérieure de Chimie de Paris, France) have prepared a number of ferrocenyl derivatives of the well-established tamoxifen drug. These compounds showed a strong antiproliferative effect, probably linked to their cytoxicity, on both hormone-dependent (MCF-7) and hormone-independent (MDA-MB-231) breast cancer cells. The authors suggest that the mechanism of action of these molecules differs from that of tamoxifen and highlight their ability to complex divalent cations such as Zn²⁺ and Ca²⁺.

“A new series of ferrocifen derivatives, bearing two aminoalkyl chains, with strong antiproliferative effects on breast cancer cells”, Pascal Pigeon, Siden Top, Anne Vessières, Michel Huché, Meral Görmen, Mehdi El Arbi, Marie-Aude Plamont, Michael J. McGlinchey and Gérard Jaouen, New J. Chem., 2011, Advance Article, DOI: 10.1039/C1NJ20192A (Paper)

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In this NJC “Hot Article”, Jian Hua Zhu and co-workers at Nanjing University (China) describe the immobilization of Horseradish peroxidase (HRP) on periodic mesoporous organosilicas (PMO).

It is demonstrated that the enzyme activity is enhanced 110% compared with free HRP in solution. Besides, the stability of immobilized HRP to lower pH values or the denaturing agent urea is enhanced, resulting from interfacial activation of the enzyme when it is attached to a surface filled with organic groups and hydrophobic parts. The thermal stability of immobilized HRP on PMO is also increased and, moreover, the HRP immobilized samples can be reusable for many cycles.

“Elevating enzyme activity through the immobilization of horseradish peroxidase onto periodic mesoporous organosilicas” Na Lin, Ling Gao, Zhe Chen and Jian Hua Zhu, New J. Chem., 2011, Advance Article. DOI: 10.1039/C1NJ20311H.

Take time to have a look at it now ! Highly rated by the reviewers and the editorial office, this “Hot Article” will be FREE to access for a period of 4 weeks.

In this NJC ‘Hot Article’, Hiroshi Nishihara and co-workers from the University of Tokyo prepared polymer particles that incorporate 3-Ferrocenylazobenzene motifs. In the solid state, the polymers can be controlled by the green-light-response (photoisomerization) and by the redox reaction of their ferrocene parts. These new entities are possible candidates to act as nano-sized photo-memories or switches.

Why not take a look at it now! Highly rated by the reviewers and the editorial office alike, this ‘Hot Article’ will be FREE to access for a period of 4 weeks.

This article will be part of the themed issue of NJC honouring the life and work of Prof. Didier Astruc, on the occasion of his 65th birthday – Coming soon.

While studying the formose reaction under hydrothermal conditions, scientists in Germany may have replicated the formation of the first sugars on prebiotic Earth.

In the formose reaction, formaldehyde undergoes self-condensation to give a mixture of sugars. The precursors are simple compounds so scientists have speculated that the reaction could have played a role in the origin of biomolecules. But, the reaction normally takes place under alkaline conditions in the presence of a catalyst.

Daniel Kopetzki and Markus Antonietti from the Max-Planck-Institute of Colloids and Interfaces in Potsdam carried out the reaction at high temperature and pressure – 200 degrees Celsius and 100 bar – to emulate conditions that would have been present in hydrothermal vents and on prebiotic Earth. They found that the sugars were produced under these conditions, too, without a catalyst or alkaline conditions.

Hydrothermal synthesis could provide greener synthesis methods as well as information about the origin of life © NOAA

‘The origin of life has been studied for well over a century but if we mean to define it as the emergence of a self-reproducing complex chemistry that is capable of evolving and sustaining itself, it is still utterly unknown,’ says Sandra Pizzarello who studies prebiotic catalysis at Arizona State University, US. ‘Darwin was among the first to touch upon the theme and foretold our current working hypothesis – that biological evolution was preceded and may have its roots in abiotic chemical evolution.’

‘We do not claim that this reaction did contribute to the formation of the first biomolecules,’ says Kopetzki, ‘but the research is of interest, as it is unclear how life emerged and therefore important to explore plausible pathways.’

So far, model systems have not shown the selectivity and specificity of life’s molecules. ‘This work reminds us of this again and points out that hydrothermal conditions might not be useful either,’ says Pizzarello.

Kopetzki says that the findings could be applied to green synthesis. ‘Water at high temperature is a beneficial solvent. Our experiments have shown that catalysts can be simplified under such conditions,’ he says. ‘Saving catalysts by employing high temperature and simple salts adds another sustainable feature.’

Amaya Camara-Campos

Hydrothermal formose reaction
Daniel Kopetzki and Markus Antonietti , New J. Chem., 2011
DOI: 10.1039/C1NJ20191C, Paper

Scientists in the UK have made metal-containing thin films that can be incorporated into wound dressings or on surfaces to kill microbes and bacteria in hospitals.

Andrew Johnson, at the University of Bath, and colleagues created the antimicrobial films from zinc and copper Schiff-base complexes incorporating ligands made by reacting aldehydes with primary amines, which they then deposited onto polypropylene fabric commonly used in nappies and bandages.

The team found that the copper and zinc complexes were good at killing microbes, and when tested against Staphylococcus aureus (which, amongst other things, causes impetigo – a bacterial skin infection – and toxic shock syndrome) and Pseudomonas aeruginosa (causes inflammation and sepsis), they were found to be highly effective, limiting bacterial growth for up to 16 hours. Techniques to reduce the prevalence of these particular bacteria are needed as they are known for their antibiotic resistance.

The zinc complex was found to be particularly successful, but the reason for this is not yet known. Johnson and his team speculate that it may be due to the toxicity of the Zn2+ ion and at higher levels may be due to transmetallation, in which the complex exchanges zinc for other vital metals in bacterial cells.

Antimicrobial zinc-based Schiff complexes could be deposited onto polypropylene fabric commonly used in nappies

Silver is a commonly used antimicrobial metal, but it is expensive so Johnson has spotted an advantage for his zinc and copper-based materials: ‘As only a small amount of the zinc monomer is required to deposit the films, it should be easy to scale up for industry and, most importantly, it will be cheap.’ Another advantage is that the ‘coatings are a post production treatment, so from a commercial perspective, we are not changing the manufacturing process for commodity bulk items such as bandages,’ he adds.

Ivan Parkin, an expert in antimicrobial coatings from University College London, UK, comments that: ‘The ability to inhibit bacterial growth on surfaces is very important.’ He adds that the work provides an indication of a new possible route to achieving this goal. However, he says: ‘It should be noted that on the treated sample, bacterial growth to the level of 106 was still seen, so complete kill has not been achieved.’

Johnson’s team now hopes to improve their films to apply them to medical devices such as catheters, wound dressings and personal care items. In particular, they are working with the paediatrics burns unit for the south-west of England at Frenchay Hospital, Bristol, to further develop their materials into advanced wound dressings for burn victims.

Holly Sheahan

Plasma deposited metal Schiff-base compounds as antimicrobials
Neil Poulter, Matthew Donaldson, Geraldine Mulley, Luis Duque, Nicholas Waterfield, Alex G. Shard, Steve Spencer, A. Tobias A. Jenkins and Andrew L. Johnson, New J. Chem., 2011
DOI: 10.1039/c1nj20091g