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 Synthesis, structure and NMR study of fluorinated isoxazoles derived from hemi-curcuminoids(Elsevier, 2019-03) Nieto Gómez, Carla Isabel; Cornago, María del Pilar; Cabildo, María del Pilar; Sanz del Castillo, Dionisia; Claramunt Vallespí, Rosa María; Elguero, JoséThe purpose of this work is to prepare a series of isoxazoles bearing phenyl and 4'-hydroxy-styryl substituents at position 3 and 5; besides the phenyl group of the styryl residue bears one or two fluorine substituents. They were prepared to study their structure in the solid state and in solution by X-ray crystallography and solid-state NMR (SSNMR) for the solid state and NMR for the solution. The reaction of hydroxylamine with hemi-curcuminoid β-diketones affords two isomeric isoxazoles we have named series a (3-phenyl) and b (5-phenyl) that have been identified and characterized. Four pairs have been prepared that in three cases bear one or two fluorine atoms. Three X-ray structures have been determined 3a, 3b and 5b; 3a crystallizes without solvent, 3b crystallizes with a water molecule hydrogen-bonded to a phenolic OH, finally 5b crystallizes as a solvate with a methanol molecule hydrogen-bonded to the isoxazole N atom. This hydrogen bond results in larger differences between 15N chemical shifts in DMSO-d6 solution and in the solid state. The splitting of some signals observed in Cross-Polarization Magic Angle Spinning (CPMAS) 13C NMR was assigned to 1JCF dipolar couplings. The combined use of crystallography and SSNMR affords a complete characterization of isomeric isoxazoles, in particular the assignment of an isoxazole to a or to b series is not a trivial matter. In this work, we describe methods for the synthesis of isoxazoles bearing fluorine substituents that are promising structures for drug discovery.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 IsabelPublicación Fluorination Effects on NOS Inhibitory Activity of Pyrazoles Related to Curcumin(MDPI, 2015-08-28) Cabildo Miranda, Mª del Pilar; Cornago, María del Pilar; Sanz del Castillo, Dionisia; Claramunt, R. M.; Torralba, M. Carmen; Torres, M. Rosario; Elguero, J.; Garcia, J. A.; Acuña Castroviejo, Darío; Nieto Gómez, Carla Isabel; López Peláez, AntonioA series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (1H, 13C, 19F and 15N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure–activity analysis allowed the establishment of a correlation between the presence/absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[β-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1H-pyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms.Publicación Synthesis, structure and biological activity of 3(5)-trifluoromethyl-1H-pyrazoles derived from hemicurcuminoids(Elsevier, 2015-11-14) Cabildo Miranda, Mª del Pilar; Cornago, María del Pilar; Sanz del Castillo, Dionisia; Claramunt, R. M.; Alkorta, Ibon; Elguero, J.; Garcia, J. A.; Acuña Castroviejo, Darío; Nieto Gómez, Carla Isabel; López Peláez, AntonioSix new 3(5)-trifluoromethyl-5(3)-substituted-styryl-1H-pyrazoles have been synthesized and their tautomerism studied in solution and in the solid state. The determination of their structures has been based on multinuclear NMR spectroscopy together with GIAO/B3LYP/6–311++G(d,p) theoretical calculations of eight structures for each pyrazole (two tautomers and four conformations). Five out of the six compounds present inhibition percentages of the iNOS isoform higher than 50%. With regard to the nNOS inhibitory activity, only two of the studied compounds show an inhibition of about 50%. Finally, concerning the eNOS, there is a compound presenting a low percentage of inhibition (40.2%) attaining in the other cases 50%.Publicación Molecular structure in the solid state by X-ray crystallography and SSNMR and in solution by NMR of two 1,4-diazepines(Elsevier, 2017-10-23) Nieto Gómez, Carla Isabel; Sanz del Castillo, Dionisia; Claramunt, Rosa María; Torralba, María Carmen; Torres, M. Rosario; Alkorta, Ibon; Elguero, JoséThe crystals of two 1,4-diazepines prepared from curcuminoid β-diketones and ethylenediamine were studied by X-ray crystallography and NMR. Their tautomerism, intramolecular hydrogen bonds and conformation were determinedPublicación The structure of β-diketones related to curcumin determined by X-ray crystallography, NMR (solution and solid state) and theoretical calculations(Springer, 2013-12-09) Nieto Gómez, Carla Isabel; Cabildo Miranda, María del Pilar; Claramunt, Rosa M.; Cornago, María del Pilar; Sanz del Castillo, Dionisia; Torralba, M. Carmen; Torres, M. Rosario; Ferraro, Marta B.; Alkorta, Ibon; Marín Luna, Marta; Elguero, JoséStructural data are reported on sixteen ketoenols of β-diketones: solution NMR, solid-state NMR (CPMAS and MAS) and X-ray crystallography (four compounds, where three are new). The emphasis is on the tautomerism between both ketoenols, in solution and in the solid state. GIAO/B3LYP/6-311++G(d,p) and Quantum ESPRESSO (QE) calculations were used and compared. For average values, the GIAO/DMSO-PCM is enough, but splittings can only be approached by using QE. A case of rotational disorder has been analyzed. Some anomalies related to C–F bonds and to the C–CF3 group have been detected.Publicación Evaluation of the antioxidant and neuroprotectant activities of new asymmetrical 1,3-diketones(MDPI, 2018-07-24) Nieto Gómez, Carla Isabel; Comago, María del Pilar; Cabildo, María del Pilar; Sanz del Castillo, Dionisia; Claramunt, Rosa María; Torralba, María Carmen; Torres, María Rosario; Martínez Casanova, Diana; Sánchez Alegre, Yaiza Rebeca; Escudero, Esther; Lavandera, José LuisA series of fourteen new asymmetrical 1,3-diketone derivatives have been synthesized and evaluated in the ABTS, FRAP and DPPH assays as a new chemotype with antioxidant and drug-like properties. All the compounds displayed low cytotoxicity in comparison to curcumin against the human neuroblastoma SH-SY5Y cell line. Among them, (3Z,5E)-6-(2,5-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (6b) and (3Z,5E)-6-(2,3-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (7b) with excellent solubility and chemical stability in biorelevant media, have also shown a similar Fe+2 chelation behavior to that of curcumin. Additionally, both derivatives 6b and 7b have afforded good neuroprotection activity against H2O2 induced oxidative stress in the same neuronal cell line, with a significant reduction of intracellular ROS levels, in parallel with a good recovery of the Mitochondrial Membrane Potential (ΔΨm). Compounds 6b and 7b with a promising antioxidant and drug-like profile, with low cytotoxic and good neuroprotectant activity, constitute a new interesting chemical class with high potential as new therapeutic agents against neurodegenerative diseases.