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This Essay tells the colourful history of the invention of the pile by Alessandro Volta and of the subsequent discovery by William Nicholson of the electrolysis of water, carried out with the Voltaic pile (1800). Indeed, as a result of the dissemination of Volta's paper among London scientists, favoured by an incorrect behaviour of the President of the Royal Society, the article by Nicholson was published months before the publication of Volta's letter. The outstanding news that electricity could be generated by a simple and easy to build instrument (the pile) was printed also by daily newspapers, which favoured its spreading all over Europe and stimulated a multitude of enthusiast practitioners and amateurs to construct their own pile and to carry out the electrical decomposition of a variety of aqueous electrolytes. The correct chemical interpretation of the pile and of electrolysis had to wait for nearly one century, but in 1800 electrochemistry was born. [ABSTRACT FROM AUTHOR]

Transition metals can be used as structural elements to build up anion receptors, enhancing H-bond donor tendencies, favouring the assembling of the molecular framework, inducing the formation of a cage. The versatile spectroscopic and electrochemical properties of the metal ion can provide a convenient signalling mechanism to communicate the occurrence of anion recognition. [ABSTRACT FROM AUTHOR]

Abstract: A versatile example of a molecular machine is described. The stationary part is an iron protoporphyrin complex, bearing two movable side chains with terminal donor groups. Changing the pH or the electrochemical potential, as well as the injection of CO, alters the affinity of the donor groups toward the metal ion, thus promoting intra-molecular motion of the pendant arms. The possibility of controlling the molecular motion through inputs of different nature, changeable at will, makes this system the first example of a hybrid molecular machine. [Copyright &y& Elsevier]

The tripodal system [1]3+ forms a 1:1 complex with CoII in which the metal is octahedrally coordinated by three bpy fragments. The [CoII(1)]5+ complex provides a cavity suitable for solvent or anion inclusion. X-ray diffraction studies on the crystalline complex salt of formula [CoII(1)…H2O]Cl(PF6)4 · 2MeCN have shown that a water molecule is included in the cavity and the water oxygen atom receives six H-bonds from the C-H fragments of the three imidazolium subunits and of the three proximate pyridine rings, according to a slightly distorted trigonal prismatic geometry. Anion inclusion in an aqueous MeCN solution induces a distinct cathodic shift of the potential of the CoIII/CoII couple, whose magnitude decreases along the series: Cl- > Br- ~ NCO- > I- ~ NCS-, which reflects anion tendencies to receive H-bonds from the receptor. The variation of the water content in the MeCN solution (from 0 to 20%) induces a gradual change of the voltammetric response to anion titration: from two well distinguished peaks at a fixed potential to a single peak progressively shifted to a more cathodic potential. Such a behavior parallels the gradual decrease of the equilibrium constant for anion inclusion into the [CoII(1)]5+ receptor. [ABSTRACT FROM AUTHOR]