Volume 3 Issue 3, March 2011

Scientists worldwide are urged to communicate their research to the public, but what is the best way to judge the effectiveness of their efforts? Using our YouTube chemistry channel as an example, we highlight the unexpected difficulty of measuring the 'impact' of such outreach activities.

Bloggers shouldn't be relegated to the sidelines of the scientific literature, argues Michelle Francl.

After two decades of research, the efficiency of dye-sensitized solar cells seems to have reached a plateau. Now, changing both electrolyte and dye opens up new opportunities that offer the hope that the efficiency ceiling can be broken.

Many different kinds of switchable molecules and materials are based on transition metal ions, but similar properties are also possible in organic materials. Now, two separate studies reveal new insights into the ability of organic radicals to associate reversibly and cooperatively in the solid state, and in so doing create bistable, hysteretic materials.

Advances in transduction of electrochemical activity through surface plasmon resonance afford new opportunities for spatially and temporally resolved studies of interfaces.

Two readily accessible synthetic building blocks are shown to form a quadruply hydrogen-bonded heterodimer that exhibits exceptional stability and offers new opportunities for the construction of supramolecular assemblies and polymers.

Arranging polymers into well-defined shapes endows them with specific properties; but although it is routinely achieved in nature, accurate origami has proved challenging with synthetic polymers. A surprisingly simple folding strategy has now been described.

Phenalenyl — a triangular neutral radical consisting of three adjacent benzene rings — and π-conjugated derivatives based on the same motif, can be viewed as 'open-shell graphene fragments'. This Perspective discusses their electronic-spin structures, the properties that arise from their unpaired electrons, and highlights their potential applications for molecular spin devices.

Purely organic materials are usually considered non-phosphorescent. Here, a crystal design that relies on the formation of halogen bonds is used to combine the heavy-atom effect with the triplet-state emission from aromatic carbonyls to produce organic crystals with bright phosphorescence of the type formerly observed only from inorganic and organometallic materials.

Dye-sensitized solar cells combining electrolytes based on the ferrocene/ferrocenium redox couple with a metal-free organic donor–acceptor sensitizer are reported to achieve a record 7.5% energy conversion efficiency, revealing the great potential of ferrocene-based electrolytes for future dye-sensitized solar cell applications.

Non-haem iron catalyst [Fe(PDP)] promotes mixed oxygenase/desaturase activity from unactivated, aliphatic C–H bonds. This novel reactivity is substrate dependent, relying on the presence of a carboxylic acid, and proceeds via a short-lived carbon-centred radical. Direct evidence for this intermediate is provided through rearrangement of a novel taxane-based radical probe.

A broad new class of commercially available multiphoton photoinitiators is identified, the properties of which result in the inverse scaling of photolithographic feature size with exposure time, rather than the usual proportional scaling. On combination with a conventional initiator, photoresists can be created for which the feature size is independent of exposure.

The potential for using molecules as wires in nanoscale electronics is somewhat tempered by the challenges in making long and uniform structures. Now, it has been shown that DNA — which is easily synthesized to precise lengths — can conduct charge over 34 nm on multiplexed gold electrodes, a distance that surpasses most reports of molecular wires.

Synthetic polymers are typically difficult to fold into particular origamis because the monomers can usually not be precisely organized along their backbones. Reactive alkyne groups have now been placed at specific locations in linear polystyrene chains, enabling those to be folded into predetermined shapes through intramolecular covalent bonding.

Palladium nanoparticles trapped within polystyrene beads can enter cells and mediate a variety of Pd⁰-catalysed reactions, including allylcarbamate cleavage and Suzuki–Miyaura cross-coupling. The methodology presented provides the basis for the customization of heterogeneous unnatural catalysts as tools for carrying out artificial chemistries within cells.

The stability of multiply hydrogen-bonded complexes can be influenced significantly by secondary electrostatic interactions between the pairs of atoms in adjacent hydrogen bonds. Now, a quadruple hydrogen-bonding array in which all of the donors are located in one component and all of the acceptors in the other has been shown to form complexes that are exceptionally stable.

Electrochemical impedance spectroscopy is a useful tool for analysing biological substances, but it remains difficult to determine local details rather than average information over an electrode surface. Now, an electrochemical impedance microscope based on plasmonics has enabled the spatial and temporal study of cellular structures and processes, with submicrometre and millisecond resolutions.

The copper(I)-catalysed azide–alkyne cycloaddition is arguably the most prolific and powerful example of the click reaction paradigm. Here, photochemical reduction of Cu(II) allows spatial and temporal control over the reaction for small-molecule synthesis, patterning of hydrogel formation and the in situ labelling of gels, with features as small as 25 micrometres being produced.

Pierangelo Metrangolo and Giuseppe Resnati celebrate the bicentenary of the discovery of iodine — a good time to also bring to its conclusion an international project that aims to define and categorize halogen bonding.