Volume 1 Issue 6, September 2009

One of the challenges facing the hydrogen economy is how to store and release the gas controllably. Although the large internal volumes of metal–organic frameworks offer promise, how can you keep the hydrogen inside?

For six days during the summer of 2009, hundreds of young researchers gathered in Germany on the shores of Lake Constance to take part in the 59th Meeting of Nobel Laureates at Lindau — this year dedicated to the topic of chemistry.

Diagnosing disease states relies on sensing imbalances in the quantities of markers present in biological fluids. Now a biologically compatible gold nanoparticle sensing-system that detects proteins in serum has been developed, offering great potential for medical diagnostics.

The exact nature of the gold–carbon bond formed during homogeneous gold catalysis has recently attracted a lot of interest and is somewhat controversial. Now a study of the bonding and trends in reactivity of various gold complexes offers new insights into whether such structures can be defined as gold-stabilized cations or gold carbenes.

New methodology that couples together carbonyl compounds with boronic acids shows much promise for synthesis owing to ease of access of the building blocks, functional group tolerance and broad scope of the reaction.

Saytzeff's rule is the result of empirical observations, and can be used to predict the outcome of elimination reactions. Now, ab initio calculations have provided the long-sought evidence to show that hyperconjugation is the key that unlocks the origin of this rule.

Small anions can be used to modulate the physical properties of supramolecular gels by interacting with the low-molecular-weight gelators from which such materials are composed. A better understanding of this anion-tuning effect will aid in the rational design of responsive gels that may prove useful for a number of practical applications.

The two established models of chemical bonding, covalent and ionic, do not accurately describe all forms of bonds. This article explains how 'charge-shift' bonds — with a large covalent–ionic resonance interaction energy — are a third type of bond, and discusses some examples.

The most stable fullerenes obey the isolated-pentagon rule (IPR): hexagons of carbon atoms entirely surround pentagons to minimize strain. Recently, some examples of fused-pentagon fullerenes have been reported and this Review summarizes current work to stabilize non-IPR fullerenes.

Protein imbalances in serum can be correlated with disease, but measurement and subsequent diagnosis is made difficult by the complex composition of serum. Now an array-based sensor, containing synthetic gold nanoparticles and biocompatible green fluorescent protein, has been developed that can detect proteins in undiluted human serum at physiologically relevant concentrations.

Better understanding of the fundamental bonding interactions at electrified metal–liquid interfaces is critical for improving the electrochemical reactions of fuel cells, but now traditional models are shown to be insufficient. Using experimental measurements of various electrocatalytic reactions on platinum and density functional theory it is shown that non-covalent interactions must be considered.

Single-walled carbon nanotubes wrapped with a carbohydrate-based polymer bearing diaminophenyl groups can be used to detect nitric oxide (NO) — an important messenger molecule for biological signalling. These polymer–nanotube hybrids are capable of real-time and spatially resolved sensing of NO in living cells, and could ultimately prove useful for in vivo detection.

An analysis of key intermediates relevant to gold(I) catalysis has been performed using density functional theory. A bonding model is proposed whereby the reactivity of gold(I)-coordinated carbenes is dependent on carbene substituents and ancillary ligands that dictate where these gold structures lie on a continuum ranging from a metal-stabilized singlet carbene to a metal-coordinated carbocation.

Porous metal–organic frameworks are promising for hydrogen storage applications, but adsorption capacities have remained too low for practical use. Now, the adsorption behaviour of such a framework has been modulated by exchanging cations within its pores resulting in either kinetic trapping or enhanced hydrogen affinity.

New economic and environmentally benign methods for achieving carbon–carbon bond formation are in constant demand. Here, a remarkably efficient and functional-group-tolerant, metal-free reductive cross-coupling of carbonyl compounds with boronic acids is described.

Carbon-nanotube networks have been used to study the sensitivity to molecular oxygen of a dendrimer complexed with europium ions. Optically transparent devices made by coating nanotubes with the metal-containing dendrimer show a linear and reversible electrical response to O₂, and may prove useful for oxygen-sensing applications.

Jim Ibers takes a look at the intriguing structures and bonding found in tellurium and its compounds, and considers their uses in a diversity of fields ranging from metallurgy to electronics.