Templating organic molecules the caesium effect

The hyperbolic nature of a number of large organic molecules such as carcerands has been demonstrated in Chapter 2. The synthesis of carcerands is eid anced by the presence of caesium salts (typically caesium carboxylate), and the efficacy of caesium in improving synthetic yields has been dubbed the caesium effect [12]. Since the caesium ions do not participate directly in the reaction chemistry, the effect has been ascribed to characteristics of this large ion alone. 

this effect can be understood in terms of the templating of hyperbolic structures, due to the presence of hyperbolic TFS, set up by the caesium ions in solution. For example, the carcerand molecule resides on the P-surface (Fig. 2.21), which is a common TFS in aqueous zeolite syntheses. The improved yield of large ring compoimds in the presence of cesium is also understandable on this basis, since the precursors to these compounds prefer to wrap around tunnels of the TFS [13]. 

In this fashion, the organic material in the animal actually determines the ultrastructure of the precipitated inorganic salts by a remarkably simple templating mechartism. These salts must precipitate within the aqueous 

Clearly, to synthesise single crystals over years in the sea, the animal must maintain an exquisite structural buffer, so that the bio-polymer assembly remains stable. But this is a pre-requisite for continued life in the animal, so there are no doubts about the ability of the creature to retain the optimal chemical environment  

The description of structure in complex chemical systems necessarily involves a hierarchical approach we first analyse microstructure (at the atomic level), then mesostructure (the molecular level) and so on. This approach is essential in many biological systems, since self-assembly in the formation of biological structures often takes place at many levels. This phenomenon is particularly pronounced in the complex structures formed by amphiphilic proteins that spontaneously associate in water. For example myosin molecules associate into thick threads in an aqueous solution. Actin can be transformed in a similar way from a monomeric molecular solution into helical double strands by adjusting the pH and ionic strength of the aqueous medium. The superstructure in muscle represents a higher level of organisation of such threads into an arrangement of infinite two-dimensional periodicity. 

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