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DFT calculations were used to access information about structure, energy and electronic properties of series of phenyl- and phenoxymethyl-(thio)semicarbazone derivatives with demonstrated activity against the larvae of Aedes aegypti in stage L4. The way as the thiosemicarbazone derivatives can interact with solvents like DMSO and water were analyzed from the comparison between calculated and experimental 1 H NMR chemical shifts. The evidences of thiosemicarbazone derivatives making H-bond interaction to solvent have provide us insights on how they can interact with a potential A . aegypti ’ s biological target, the Sterol Carrier Protein-2. [ABSTRACT FROM AUTHOR]

Principal component analysis was used in the selection of the B3PW91/6-311+G(3df) method for calculations of As2O3 molecular species. This multivariate analysis compared experimental properties (structure and ionization energy) of As4O6 molecule with several computational methods (Hartree-Fock, second-order Møller-Plesset perturbation theory, and density functional theory) and basis sets. At the selected level of theory, we were able to calculate nine structures of As2O3 with three of them being stable ones (no negative force constants) in the following stability order: D3H (0.0), DIAMOND OUT (32.77 kJ mol−1), and GAUCHE (43.81 kJ mol−1). Several intramolecular conversions were studied with the GAUCHE → DIAMOND OUT transformation being barrierless, whereas the DIAMOND OUT structure is converted into the D3H isomer through a Gibbs free-energy barrier of 40.83 kJ mol−1. Starting from the GAUCHE structure of As2O3 and its enantiomeric form, it was possible to obtain directly (barrierless) the As4O6 species in a spontaneous process (Δr G = −399.92 kJ mol−1 at 298 K and 1 atm) in gas phase. Thus, the As4O6 species is probably the precursor of arsenic hydroxide through hydrolysis reactions. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]