Persona: Sanz del Castillo, Dionisia
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Publicación Addition reaction of azoles to acetone-d 6: NMR and computational studies(Wiley, 2024-05-22) Claramunt Vallespí, Rosa María; Sanz del Castillo, Dionisia; Alkorta, Ibon; Elguero, JoséThe reactivity of imidazole, pyrazole, 1,2,4-triazole, 1,2,3-triazole and tetrazole with acetone (propan-2-one) has been studied by 1 H and 13 C NMR using acetone-d 6 as solvent at temperatures ranging from 173 to 300 K at 10 K intervals. Simultaneously, the reaction has been theoretically calculated at the B3LYP/6-311++G(d,p) level and experimental and theoretical results compared. The equilibrium constants between azoles and adducts α,α-dimethyl-azole-methanol were analyzed assuming that the straight part of the plots –R ln Ke vs. 1/T can be used to determine ΔH and ΔS. Calculated and experimental data are related but the theoretical values are proportionally higher. The tautomerism of triazoles and tetrazole has been considered in order to discuss the reactions.Publicación Curcumin Related 1,4-Diazepines: Regioselective Synthesis, Structure Analysis, Tautomerism, NMR Spectroscopy, X-ray Crystallography, Density Functional Theory and GIAO Calculations(Wiley, 2017-05-02) Andrade, Ana; Claramunt, Rosa María; Torralba, M. Carmen; Torres, M. Rosario; Alkorta, Ibon; Elguero, J.; Nieto Gómez, Carla Isabel; Sanz del Castillo, DionisiaThe reaction of 1,2-ethylenediamine with seven fluorinated β-diketones affords two different 1,4-diazepine series depending on the experimental conditions. Their structures as well as tautomerism have been established by 1H, 13C, 15N and 19F nuclear magnetic resonance in solution supported by density functional theory calculations at the B3LYP/6-311++G(d,p) level. The two compounds obtained from (E)-5-(2-fluoro-4-hydroxyphenyl)-1-phenylpent-4-ene-1,3-dione were analyzed by X-ray crystallography and studied by solid-state NMR.Publicación Determination of the tautomerism of albendazole desmotropes using solution and solid state NMR together with DFT theoretical calculations, both energies and chemical shifts(Elsevier, 2022-08-05) Claramunt Vallespí, Rosa María; López García, Concepción; Sanz del Castillo, Dionisia; Elguero, José; Alkorta, IbonThis paper reports a structural study of albendazole concerning the desmotropy of its amino and imino tautomers, ABZ-I and ABZ-II, mistakenly called polymorphs. Experimental NMR determination in solution, DMSO-d6, HMPA-d18 and CF3 CO2 H, and in the solid state, CPMAS, together with DFT calculations, energies and NMR chemical shifts, has allowed to understand the complex problem of prototropy combined with rotation about the benzimidazole C2-N exocyclic group that explain the disorder problem of the S-propyl group. The structure of protonated albendazole, ABZH +, has also been studied. The role of the hybrid HF/DFT B3LYP computational method at the B3LYP/6-311++G(d,p) level has been determinant to solve the problems related to the structure of albendazole in the solid state and in solution and the barrier in solution of a phenomenon resulting either from annular tautomerism or from the rotation about the exocyclic C-N bond.Publicación A multinuclear magnetic resonance study of fluoro derivatives of hydroxybenzaldehydes(2015-06-06) Claramunt, Rosa María; Alkorta, Ibon; Elguero, J.; Sanz del Castillo, Dionisia; Nieto Gómez, Carla Isabel