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Quick and clean way to make intermediates for dyes and pharmaceuticals

30 Jul 2012

Scientists in China have developed a quick and clean way to reduce nitroarenes to aminoarenes, which are common intermediates for making dyestuffs, pharmaceuticals and agricultural chemicals.

Sodium borohydride and molecular hydrogen are commonly used for this reaction but their hydrogen elements cannot reduce nitroarenes under mild reaction conditions. Usually, expensive noble-metal catalysts are necessary to activate the hydrogen elements in the reductants.

Here, the researchers have used a vanadium-doped porous TiO₂ with highly active hydrogen, which can instantly (<10s) and selectively reduce nitroarenes to aminoarenes under ambient conditions without catalysts. After being consumed by nitroarenes, the active hydrogen species can be regenerated by irradiating the V-doped TiO₂ with UV light.

Link to journal article
Porous vanadium-doped titania with active hydrogen: a renewable reductant for chemoselective hydrogenation of nitroarenes at ambient condition
J Su et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33969b

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Silica sheets to deliver DNA into cells for disease prevention and treatment

17 Jul 2012

Scientists in Japan have made a new DNA delivery substrate based on networks of bio-friendly upright silica sheets. The network of sheets forms a porous film on to which they can immobilise DNA, ready for delivery (transfection) into cells. The transfection efficiency of the silica film is approximately double that of solution-based transfection. Gene transfection is a potential method for preventing and treating diseases and analysing cell functions.

Link to journal article
Silica-based Gene Reverse Transfection: Upright Nanosheet Network for Promoted DNA Delivery to Cell
Q Ji et al
Chem. Commun., 2012, DOI: 10.1039/c2cc34289h

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Bendy non-volatile flash memory data storage device

11 Jul 2012

Scientists in Taiwan have made a flexible memory device, which they say could open up a new design approach for high performance flexible non-volatile resistive memory devices. Non-volatile devices are computer memory devices that can retain stored information even when not powered, for example read-only memory, flash memory, hard drives and floppy disks.

The team’s device consists of a single-layer donor-acceptor conjugated polymer fabricated on plastic polyethylene naphthalene. It displayed a low threshold voltage (±2V), low switching power (~100µW cm^-2), large on/off memory window (10⁴), good retention (>10⁴s) and excellent endurance against electrical and mechanical stimuli, they say.

Link to journal article
Poly(fluorene-thiophene) Donor Tethered Phenanthro[9,10-d]imidazole Acceptor for Flexible Nonvolatile Flash Resistive Memory Devices
H-C Wu et al
Chem. Commun., 2012, DOI: 10.1039/c2cc34257j

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A new type of conducting polymer

05 Jul 2012

Scientists in the US have reported a new type of conducting polymer, generated by a ROMP (ring opening metathesis polymerisation) reaction. The new polymers could have potentially useful properties, they say.

They reacted the complex (η⁵-C₅H₅)Ir(η⁴-C₆H₆) with Grubbs’ catalyst to give a polyacetylene consisting of cyclopentadienyliridium bound s-cis butadiene moieties separated by C=C linkages, a previously unavailable polyacetylene type.

Link to journal article
Ring Opening Metathesis Polymerization of an η⁴-Benzene Complex: A Direct Synthesis of a Polyacetylene with a Regular Pattern of Π Bound Metal Fragments
P D Zeits, T Fiedler and J A Gladysz
Chem. Commun., 2012, DOI: 10.1039/c2cc32150e

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Film to aid drug metabolism study

05 Jul 2012

A way to study drug metabolism using cytochrome P450 enzymes (which are involved in the metabolism of over 60% of clinically used drugs) has been developed by scientists in China.

The team made a film of indium tin oxide nanoparticles (they have good conductivity) and cytochrome P450s encapsulated by chitosan (which are biocompatible) on a carbon electrode. They were able to bioelectronically initiate cytochrome P450 catalysis by replacing electron donation from expensive nicotinamide adenine dinucleotide phosphate with electrodes.

The system has potential for applications in drug discovery and development by monitoring substrate metabolism and enzyme inhibition. Other applications include biosensors for toxicity analysis and bioreactors for chemical synthesis.

Link to journal article
Electrochemically Driven Drug Metabolism via Cytochrome P450 2C9 Isozyme Microsomes with Cytochrome P450 Reductase and Indium Tin Oxide Nanoparticle Composites
X Xu et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33575a

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Macrocycle insulation for molecular wires

05 Jul 2012

Researchers in Texas are using rotaxane formation to sterically protect or “insulate” molecular wires.

Molecular wires, in which an unsaturated linker separates two or more redox active metal sites, are of great research interest. These structures allow phenomena such as electron delocalisation or transport between the two redox sites. John Gladysz’s group at Texas A&M University have an ongoing interest in dimetallic polyynediyl complexes, in which two metal centres are linked by conjugated polyynediyl linkers that they now hope to “insulate” to reduce interactions between wires and the external environment. A previous approach used long alkyl bis-phosphine, which wrapped around the wire in a double helix to complex both metal centres. However, this gave two enantiomers, which interconverted rapidly in solution via uncoiling of the protective ligands.

The Gladysz group are now reporting a straightforward solution to this problem. They found that by synthesising their bis-platinum wire in the presence of a 33-membered macrocycle, they could incorporate the wire as the thread of a rotaxane complex. This provides a more robust protection for the wire which is unaffected by dynamic processes.

space filling representation of the rotaxane

This work shows a fantastic application of rotaxane chemistry for protection of a molecular wire. What’s more, the synthesis of this rotaxane is adaptable, and the Gladysz group are working on exciting new and improved systems including longer polyynediyl linkers and redox inactive macrocycles to improve the properties of the insulated wires.

The full communication can be downloaded here.

Cally Haynes

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Deadline Approaching – ICPOC 21 poster abstracts

29 Jun 2012

There is still just time to submit your poster abstract to the 21st IUPAC International Conference on Physical Organic Chemistry (ICPOC 21) but don’t delay.

The deadline date of 13 July is for both poster abstracts and early bird registrations.

Why join ICPOC21?

Professor Hiromitsu Maeda, Ritsumeikan University, Japan has won the 2012 ChemComm Emerging Investigator Lectureship and will delivering his lecture at ICPOC 21.

This annual award recognises an emerging scientist in the early stages of their independent academic career. Professor Maeda’s has been particularly commended for his contributions to the fields of organic chemistry, supramolecular chemistry and materials science.

In addition to the outstanding plenary sessions, there will be three parallel sessions over the five days comprising invited lectures and contributed talks, as well as poster sessions.

A broad range of scientists from across the whole community who share a quantitative perspective on chemistry will be there, providing an opportunity to discuss and celebrate the current status, development, and the future of physical organic chemistry.

Make sure you are one of them! Don’t miss the poster abstract submission and early bird registration deadline – 13 July.

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A new catalyst for asymmetric aziridination

26 Jun 2012

Aziridines are used extensively as intermediates for organic synthesis. The strained three-membered heterocycles reveal amino groups on ring-opening and therefore provide access to a variety of useful products. Enantioselective methods for forming aziridine rings are highly desirable because enantiopure amino-compounds represent important targets for both natural product synthesis and in the discovery of novel therapeutics.

Researchers from Kyushu University in Japan have reported a newly designed Ru(CO)salen complex (4), which acts as an efficient catalyst for asymmetric aziridination of alkenes.

Reaction of olefinic substrates (1) with 2-(trimethylsilyl)ethanesulfonyl (SES) protected azide (2) in the presence of the Ru(CO)salen complex 4 afforded enantioenriched aziridine products. 4 efficiently decomposes azides under ambient conditions and also catalyses asymmetric aziridination.

Judicious selection of an appropriate azide protecting-group also influenced the design of the catalyst. The researchers chose to include an appropriately located C–F bond within the ligand in order to improve tolerance of 4 to reacting electrophiles.

Low catalyst loadings enabled the highly enantioselective azirdination of a variety of substrates possessing conjugated or non-conjugated terminal or cyclic olefins.

Find out more – download the communication for free for a limited period.

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Additional benefit of cancer drug

21 Jun 2012

A new clinically used cancer drug thought to work by inhibiting kinase enzymes also strongly inhibits carbonic anhydrase (CA) enzymes, reveal scientists in Italy.

Scientists did not evaluate the CA inhibition activity of pazopanib before its approval for the treatment of a variety of different cancers, including lung, breast and ovarian cancers. But Claudiu Supuran and colleagues recognised part of the drug’s structure – a primary sulfonamide moiety – is often found in drugs that can inhibit CAs. So they tested pazopanib along with some other related structures and found that the drug did indeed inhibit CAs. They estimate that a significant proportion of the drug’s therapeutic effect on hypoxic tumors is due to its strong CA inhibitory properties.

Link to journal article
Polypharmacology of sulfonamides: Pazopanib, a multitargeted receptor tyrosine kinase inhibitor in clinical use, potently inhibits several mammalian carbonic anhydrases
J-Y Winum et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33415a

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Porphyrins and Phthalocyanines – free access to articles for limited period

13 Jun 2012

ChemComm Editor Robert Eagling will be attending the seventh International Conference on Porphyrins & Phthalocyanines (ICPP-7) in Jeju, Korea on 1-6 July 2012.

Two of the conference co-chairs – ChemComm Associate Editor Jonathan Sessler and Changhee Lee from Kangwon National University – are the guest editors of ChemComm‘s Porphyrins & Phthalocyanines web theme issue, along with ChemComm Editorial Board member Penny Brothers.

To celebrate this exciting and vibrant area of research, we have made the whole of our Porphyrins & Phthalocyanines web theme FREE to access until 6th July. So don’t delay – view the web theme today!

Will you be attending ICPP-7? Email Robert if you’d like to arrange a meeting. Post your comments on the conference or the web theme below or tweet us @ChemCommun.

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Chemical Communications Blog

Archive for the ‘Subject Areas’ Category

Quick and clean way to make intermediates for dyes and pharmaceuticals

Silica sheets to deliver DNA into cells for disease prevention and treatment

Bendy non-volatile flash memory data storage device

A new type of conducting polymer

Film to aid drug metabolism study

Macrocycle insulation for molecular wires

Deadline Approaching – ICPOC 21 poster abstracts

A new catalyst for asymmetric aziridination

Additional benefit of cancer drug

Porphyrins and Phthalocyanines – free access to articles for limited period

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