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We report a microcalorimetry study of the association of various inorganic and organic cations with p-sulfonatocalix[4]arene at 298.15 K. First, we have studied the electrostatic attraction between host 1 and seven rare-earth-metal cations representative of the whole lanthanide series (La 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Dy 3+ and Yb 3+ ) in an acidic solution (pH 2). In order to compare the charge effects in the electrostatic interactions we have also studied the attraction between host 1 and two alkaline-earth-metal cations (Ca 2+ and Mg 2+ ). Next, we investigated the binding of a series of quaternary ammonium cations in an acidic solution (pH 2). For each system, both the apparent association constant and enthalpy of complexation have been extracted from the calorimetric data. In all cases, our results are consistent with the formation of 1 : 1 complexes. Whereas for the inorganic cations (alkaline-earthmetal and lanthanide cations) the association process is enthalpically unfavoured (∆ r H Њ>0) and entropically favoured (∆ r SЊ>0), the complexation is driven by a favourable enthalpy change for the organic cations. These thermodynamic properties show that the organic and inorganic cations bind in very different modes.

The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km 2 and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R&D studies and is reviewed here in detail.

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Gibbs free energies, enthalpies and entropies for the binding of Na+, K+, Rb+, Cs+, Ag+, Tl+ and NH4+ by the p-sulfonatocalix[4]arene in water are determined by microcalorimetry. Whereas no significant heat effect is detected with Na+ or Ag+, suggesting that these cations are not complexed, weak but selective binding is observed with the other cations. The whole set of thermodynamic parameters, which demonstrate that the cations bind inside the cavity of the calixarene, evidence the importance of the cation-pi interactions for these complexes in water.

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