A squaraine rotaxane that can undergo reversible photochemical oxidation acts as a light 'store' and can be used for optical imaging (shown conceptually on the cover). Smith and co-workers show that irradiation of the parent rotaxane with red light in the presence of oxygen generates an endoperoxide that is stable at low temperature. When warmed to body temperature, the reverse reaction occurs spontaneously, producing singlet oxygen and a photon of near-infrared light.

Cover design by Alex Wing/Nature Chemistry, based on an original image by Aleksandr Bosoy (Northwestern University).

Article p1025

The barrel-like structure of the heptameric-pore-forming protein ɑ-haemolysin can be used as a 'nanoreactor' to study the reactions of single molecules. Now, Hagan Bayley and co-workers have engineered a pore in which one of the seven subunits contains a cysteine residue. The thiol side-chain of this amino acid can react with a quinone inside the pore (shown conceptually on the cover) and the ion current through the pore used to study the reaction kinetics. a deuterium-isotope effect — in a mechanistic step that occurs after the rate-determining step — has been observed for the first time.

Cover design by Alex Wing/Nature Chemistry.

Article p921

News & Views p905

The determination of molecular structure is an important step in the potential applications of naturally occurring organic compounds with interesting biological activity. For a significant fraction of newly isolated natural products, however, standard analytical techniques such as NMR and mass spectrometry cannot provide a definitive structure. Now, Leo Gross and co-workers have used a scanning probe microscopy technique to obtain an atomic-resolution image (shown on the cover) of a single molecule of cephalandole A, thereby enabling an unambiguous assignment of its structure. Image courtesy of Leo Gross, IBM Research-Zurich.

Cover design by Alex Wing/Nature Chemistry.

Article p821

News & Views p799

Nuclear power is a key element of our energy mix, and uranium nitride [U≡N]x is a promising alternate nuclear fuel; however, very little is known about the U≡N functionality. Now, Kiplinger, Batista and co-workers have made a uranium azide complex that interacts with light to lose dinitrogen and produce a transient uranium nitride complex (shown conceptually on the cover). This is the first uranium nitride compound to be accessed through photolysis. Image courtesy of Anthony Mancino.

Cover design by Alex Wing/Nature Chemistry.

Article p723

News & Views p705

Solvation can have a huge impact on the structure and function of proteins. Although water is typically the best environment for proteins, some retain their activity in non-aqueous solvents. Now, Mann and co-workers have gone a step further and shown that solvent-free protein liquids — comprising polymer-modified myoglobin that adopts a near-native structure — exhibit reversible dioxygen-binding ability equivalent to that observed under physiological conditions. These room-temperature protein melts (illustrated conceptually on the cover) challenge the conventional wisdom about the role of solvent molecules in biomolecular function, and offer new opportunities in protein-based nanotechnology. Image courtesy of Warwick Bromley.

Cover design by Alex Wing/Nature Chemistry.

Article p622

News & Views p607

A combined theoretical and experimental study by Matile and co-workers on a series of substituted naphthalenediimides reveals that increasing the pi-acidity of the aromatic system leads to stronger interactions with anions, and results in more effective and selective anion transport across lipid-bilayer membranes. Although the most pi-acidic compound used in this study is a dicyano derivative with a quadrupole moment of +39 Buckinghams, the cover image shows an artist's impression of an elusive +56 Buckinghams-aromatic system with four cyano groups (image courtesy of Roanna Dawson).

Cover design by Alex Wing/Nature Chemistry.

Article p533

News & Views p516

The controlled contraction and expansion of molecular systems has the potential to be harnessed in nanomechanical devices. Such motions can be achieved in double-helical systems by changing how tightly the two strands are wound up. it has now been shown that in optically active helical systems made up of two hexaphenol strands, sodium ions can be used to trigger the anisotropic twisting of the system (as shown on the cover of this issue) to produce expanded and contracted forms of the helicate without racemization.

Cover design by Alex Wing/Nature Chemistry.

Article p444

News & Views p429

The magnetic properties of single-molecule magnets generally originate from a superexchange mechanism in which the spin states of two neighbouring metal ions couple to one another. Now, Long and co-workers have shown that a mixed-valence divanadium cluster with a bridging imidazolate ligand - shown on the cover of this issue - possesses a high-spin ground state that arises from a double-exchange mechanism based on electron delocalization. The versatility of imidazolate ligands in generating coordination complexes suggests that this could be a promising approach for producing a range of magnetic molecular materials. Cover image courtesy of Jeffrey D. rinehart.

Cover design by Alex Wing/Nature Chemistry.

Article p362

News & Views p351

The pentagons of carbon in most stable fullerenes do not share their edges with one another, but there are some examples that break this 'isolated pentagon rule'. Such compounds, with two fused pentagons, are highly reactive unless stabilized by other modifications of the fullerene cage - such as chemical derivatization. Now, Xie, Lu and co-workers have made stable fullerenes (shown on the cover) with structures in which three pentagons are fused together in a line.

Cover design by Alex Wing/Nature Chemistry.

Article p269

Investigating the dynamics of a single biomolecule typically involves either attaching it to a surface, which may alter its behaviour, or making only fleeting observations in solution before it diffuses away. Now, Goldsmith and Moerner have used a technique that cancels out diffusion to trap single molecules of the photosynthetic antenna protein, allophycocyanin, in solution for over one second. This enables them to measure how the fluorescence of this molecule changes during the course of the observation, as shown conceptually on the cover (image courtesy of Randall Goldsmith and Steven Lee).

Cover design by Alex Wing/Nature Chemistry.

Article p179; News & Views p157

Naturally occurring molecular machines perform specific biological functions and provide inspiration for chemists trying to make synthetic analogues. Now, David Leigh and co-workers have made a small molecule that 'walks' down a track in a manner similar to motor proteins. The synthetic walker - shown conceptually on the cover with, in the background, kinesin walking along a microtubule - moves progressively with a 'passing-leg' gait by forming dynamic covalent bonds between each of its feet and the footholds of the track. Cover: foreground image from David Leigh and co-workers; background image is a still from Inner Life of the Cell, Harvard University, © 2006 The President and Fellows of Harvard College, created by robert Lue and alain viel, Harvard University, in collaboration with XVIVO, LCC.

Cover design by Alex Wing/Nature Chemistry.

Article p96; News & Views p75

The properties of nanoparticles are strongly influenced by their size, and it is often desirable to produce samples in which the particles all have the same - or very similar - sizes. This is not a simple proposition, however, because nanoparticles are usually formed in a range of sizes. Fujita and co-workers have now shown that well-defined cages self-assembled from metal ions and organic ligands can template the formation of silica nanoparticles within their hollow cavities (as shown on the cover) with almost perfect size control.

Cover design by Alex Wing/Nature Chemistry.

Article p25; News & Views p6