Reviews Self-assembly From the formation of polar ice
caps, the discussion also becomes relevant for the understanding of our current and future climate. As geologists, the authors hold no romantic attachment to one set of conditions or another. Over geologic timescales, Earth has seen a wide variety of climates, and life has survived all of them. But they are well-positioned to appreciate the fact that the stability that allowed our civilisation to prosper is highly unusual and fragile. Things that we regard as permanent, like the sea level and the outlines of the continents, could change quite drastically. The authors conclude: ‘We are vigorously rocking a boat that has shown a marked tendency to capsize.’ Venturing a look into the crystal
ball with their final chapter, the authors reckon that, owing to the carbon dioxide shock that we have produced, sea levels may adjust around Pliocene height, which means 10–20m above present levels. The man-made geological epoch, which many now call the Anthropocene, will derail one or two of the 100,000-year geological cycles timed by astronomical constellations. So, the only reassurance they can offer is that in 200,000 years Earth will be back to normal. Essentially, we were very lucky, we had a perfect chance, and we messed it up.
Michael Gross is a science writer based in Oxford, UK.
The importance of ionic interactions
M
acromolecules are so ubiquitous that we often forget that it was not until 1953 that German chemist Hermann Staudinger received the Nobel prize in chemistry for clarifying these immensely complicated substances, although ‘real’ organic chemists had derided their study as Schmierchemie, meaning messy or grease chemistry. While we are familiar with myriad natural and synthetic polymers we are not so familiar with how ionic interactions play a primary role in the self-assembly of these systems. Combinations of supramolecular interactions direct a variety of self-assembly modes for nano-architectures and functional biostructures. The theoretical features of purely ionic
interactions have been extensively described in the past and structural features of a number of real systems in which ionic interactions play a prevailing role have been experimentally characterised. In most real cases, however, ionic interactions are modulated – reinforced or antagonised – by other charge- independent interactions to produce important alterations of the structure and properties of the systems.
Ion pairing plays a significant role in the design of
supramolecular complexes, particularly in an aqueous environment, where the presence of charges also secures sufficient solubility. Salt bridges between host–guest compounds bearing complementary charges allow the reversible formation of associations with many important biological targets such as nucleotides, saccharic acids, peptides, biogenic amines etc. Although the most important applications of synthetic host–guest complexes are in analytical chemistry, they also play an increasingly significant role in separations, drug design and delivery, polymers with smart functions and other technologies. This book presents a detailed description of how the components of chemical recognition are modified to produce the wide variety of properties that characterise the supramolecular organisation of functional systems and adaptive polymers. The first and second parts deal with fundamental aspects of purely ionic interactions and mixed interactions, respectively. The third part focuses on functions and applications of various systems such as iron transport in living cells; DNA-lipid amphiphiles for drug and gene therapy; polyelectrolyte intelligent gels; ionic polymer–metal composites for sensors
and artificial muscles; among others. This is a comprehensive text that explains the latest advances in the large class of natural and synthetic materials influenced by ionic-mixed interactions and their many potential applications. It should be of interest to practitioners and students in chemistry, biochemistry, physics, and engineering.
George B. Kauffman is professor of chemistry at California State University, Fresno, US.
Ionic interactions in natural and synthetic macromolecules
Editors Alberto Ciferri and Angelo Perico Publisher Wiley Year 2012 Pages 852 Price £117 ISBN
978-0-470-52927-0
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Dr Arthur Lesk MRC Laboratory of Molecular Biology/Science Photo Library