The energetic stability and structural and electronic properties of all the ketonic and enolic tautomers of neutral hypoxanthine are studied at the level of density functional theory. We also study the influence of temperature on the tautomeric equilibria and the IR vibrational spectrum of this heterocycle in the gas phase in terms of the contributions of several tautomers. We found that the two N(1)-H ketonic tautomers of hypoxanthine are the energetically most stable ones and represent the main contribution to the experimental IR spectrum. The calculated properties and the potential chemical behavior suggested for hypoxanthine from the theoretical study are in remarkable agreement with the experimental data reported up to date.

Apparent molar heat capacities at 25 °C of a series of 1-alcohols and three branched alcohols were determined in mixtures of the type alcohol + (p wt % AOT + n-decane) at R = 0 and 10, R being the water−surfactant molar ratio [W]/[S]. For methanol and 1-hexanol, the measurements were done for different p values as a function of alcohol concentration. For all the other alcohols p = 5. Heat capacities for the binary (AOT + nC10) and the ternary (AOT + W + nC10) mixtures, as well as for 1-hexanol in a 5 wt % solution of dioctyl succinate, were also measured at 25 °C. For all alcohols + AOT + n-decane, kinematic viscosities and dynamic light scattering (DLS) were measured at 25 °C for R = 10 and p = 13 as a function of alcohol concentration. DLS was also measured for the ternary mixture AOT + W + nC10 with R = 10 at 25 °C. A reasonable molecular picture of the alcohol−AOT interactions in the presence and absence of reverse micelles emerges from the experimental DLS and heat capacity results, the latter having been analyzed within the Treszczanowicz−Kehiaian model framework. In the absence of reverse micelles, all alcohols form complexes with the free AOT molecules in the solution, a process that competes with the alcohol self-association. The alcohol−AOT complex is most probably formed via an interaction between the hydroxyl group of the alcohol and the ionic head of AOT. When reverse micelles are present, two behaviors were found:  (i) Methanol and ethanol are located in the micelle water pool; at low AOT concentration these alcohols only interact with water, but at higher AOT concentration they also form a complex with AOT molecules at the micellar interface. (ii) For butanol, longer 1-alcohols, and the three branched alcohols studied here two different processes occur:  AOT molecules are withdrawn from the micelles to be complexed with alcohol molecules in the bulk of the solution, and alcohol molecules penetrate the micellar shell, where they also form a complex with AOT.

A Gibbs ensemble Monte Carlo calculation of the properties of water using the four point transferable intermolecular potential with fluctuating charges model (TIP4Pfq) is presented. The model yields very good results for the thermodynamic properties, comparable with the ones obtained with fixed charges models and with the experimental data. Remarkable results for the liquid phase chemical potential at room temperature are obtained. The dielectric constant calculation is improved with respect to the model with fixed charges, and gives similar results when compared with a molecular dynamics simulation for the same water model. The intermolecular potential model used here seems to be a promising one for studying the properties of aqueous solutions, where the dielectric behavior of the solvent makes a direct and substantial contribution to the solution properties.

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The synthesis in aqueous solution and pH = 1.0 of several novel Cu(II) compounds with allopurinol and hypoxanthine as heterocyclic ligands and X = Cl(-), Br(-), NO(3)(-), SO(4)(2-), and ClO(4)(-) as anions, together with their spectral and magnetic characterization, is reported. The studies of the Cu(II) systems with these heterocycles and Cl(-) or Br(-) support their Cu(II)(L)(2)(X)(2) character and their interactions through halogen atoms as bridging ligands, leading to a very weak antiferromagnetic coupling. For the Cu(II) compounds with hypoxanthine and X = NO(3)(-), SO(4)(-), or ClO(4)(-), new examples of the cupric acetate type are obtained, showing in all cases similar strong antiferromagnetic coupling. These three cases are new examples of the scarce Cu(II) dinuclear compounds with bridging hypoxanthine which have been reported up to now.