José María Leal

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A theoretical and experimental study on the structure and deprotonation of benzohydroxamic acid (BHA) has been performed. Calculations at the RHF/cc-pVDZ level, refined by the B3LYP/AUG-cc-pVDZ method, indicate that, in the gas phase, Z amide is the most stable structure of both neutral and deprotonated BHA. (1)H-(1)H nuclear Overhauser enhancement(More)
The mechanism of the protonation of acetohydroxamic acid is investigated comparing experimental results and ab initio calculations. Experimentally, the UV spectral curves were recorded at different temperatures, at constant dioxane/water concentration, and at very high concentrations of strong mineral acids. The process is followed by monitoring the changes(More)
Doxorubicin (DOX) is an important anthracycline antibiotic whose intricate features of binding to DNAs, not yet fully understood, have been the object of intense debate. The dimerization equilibrium has been studied at pH = 7.0, I = 2.5 mM, and T = 25 °C. A thermodynamic and kinetic study of the binding of doxorubicin to DNA, carried out by circular(More)
The interaction of thionine with triple, double, and single RNA helices has been fully characterized by thermodynamic and kinetic methods. The nature of the interaction of thionine with the synthetic polynucleotides poly(rU), poly(rA)·poly(rU), and poly(rA)·2poly(rU) has been studied at pH = 7.0 and 25 °C by UV absorbance, fluorescence, circular dichroism(More)
The interaction of coralyne with poly(A)*poly(U), poly(A)*2poly(U), poly(A) and poly(A)*poly(A) is analysed using spectrophotometric, spectrofluorometric, circular dichroism (CD), viscometric, stopped-flow and temperature-jump techniques. It is shown for the first time that coralyne induces disproportionation of poly(A)*poly(U) to triplex poly(A)*2poly(U)(More)
The acid-base behavior and self-aggregation of salicylhydroxamic (SHA) and p-hydroxybenzohydroxamic acids (PHBHA)have been investigated by UV and 1HNMR spectroscopy, respectively. The acid-base parameters, measured in H2O at 25 degrees C and I=0.1 M, were pK1=7.56, pK2=9.85 for SHA and pK1=8.4, pK2=9.4 for PHBHA. The 1H NMR signals for salicylhydroxamic and(More)
The synthesis and full characterization of the new aqua-complex [(η(6)-p-cymene)Ru(OH2)(κ(2)-N,N-2-pydaT)](BF4)2, [2](BF4)2, and the nucleobase derivative [(η(6)-p-cymene)Ru(9-MeG)(κ(2)-N,N-2-pydaT)](BF4)2, [4](PF6)2, where 2-pydaT = 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine and 9-MeG = 9-methylguanine, are reported here. The crystal structures of both(More)
The binary mixtures of methanol with (C(1)-C(4)) alkylbenzoates and of (C(1), C(3), C(5), C(7), C(9), C(11)) alkan-1-ols with methylbenzoate were used as solvents to look into the preferential solvation and intermolecular interactions of the solvatochromic indicators 2-nitroanisole, 4-nitroaniline, 4-nitrophenol, and Reichardt's dye by UV-vis measurements.(More)
Subnanometric samples, containing exclusively Ag2 and Ag3 clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag3 clusters interact with DNA through(More)
The role of solvent effects on the thermodynamics and kinetics of the coralyne self-aggregation process has been investigated in ethanol-water mixtures of different compositions. The changes in the UV/visible spectra of coralyne and FAB/LSIMS mass spectrometry agreed well with the formation of a dimer species. 1D and 2D 1H experiments have allowed one to(More)