There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Silver nanoparticles as a new generation of antimicrobials.

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Antimicrobial effects of silver nanoparticles

The successful isolation and characterization of an N-heterocyclic carbene in 1991 opened up a new class of organic compounds for investigation. From these beginnings as academic curiosities, N-heterocyclic carbenes today rank among the most powerful tools in organic chemistry, with numerous applications in commercially important processes. Here we provide a concise overview of N-heterocyclic carbenes in modern chemistry, summarizing their general properties and uses and highlighting how these features are being exploited in a selection of pioneering recent studies.

An overview of N-heterocyclic carbenes

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

Methods: After impregnation the nature of the impregnation was determined by transmission electron microscopy. Two series of polymer discs were then tested, one washed in deionized water and the other unwashed. In each series, half of the discs were coated with a plasma protein conditioning film. The serial plate transfer test was used as a screen for persisting activity. Bacterial adherence to the polymers and the rate of kill, and effect on planktonic bacteria were measured by chemiluminescence and viable counts. Release rates of silver ions from the polymers in the presence and absence of plasma was measured using inductively coupled plasma mass spectrometry (ICP-MS). Results: Tests for antimicrobial activity under various conditions showed mixed results, explained by the modes and rates of release of silver ions. While washing removed much of the initial activity there was continued release of silver ions. Unexpectedly, this was not blocked by conditioning film. Conclusions: The methodology allows for the first time silver impregnation (as opposed to coating) of medical polymers and promises to lead to an antimicrobial biomaterial whose activity is not restricted by increasing antibiotic resistance.

Silver nanoparticles and polymeric medical devices: a new approach to prevention of infection?

Abnormal N-heterocyclic carbenes

F-block N-heterocyclic carbene complexes.

Since the discovery of a stable “bottleable” N-heterocyclic carbene (NHC), there has been a spectacular explosion of interest in this ligand class. This interest stems from a desire to understand the fundamentals of the structure and bonding of these systems, but also because of their numerous and emerging applications in small molecule activation, homogeneous catalysis and Lewis acid-catalysed reactions. In this Tutorial Review, we introduce the reader to NHCs, cover general synthetic methods to prepare anionic tethered NHCs and their metal complexes, and discuss emerging applications in reactivity and catalytic studies.

Polly L. Arnold

Papers

Silver nanoparticles and polymeric medical devices: a new approach to prevention of infection?

Abnormal N-heterocyclic carbenes

F-block N-heterocyclic carbene complexes.

Anionic tethered N-heterocyclic carbene chemistry

Arene-Bridged Diuranium Complexes: Inverted Sandwiches Supported by δ Backbonding