Persona: Nieto Gómez, Carla Isabel
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Nieto Gómez
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Publicación An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism(Beilstein-Institut, 2014) Nieto Gómez, Carla IsabelThis paper reports the 1H, 13C and 15N NMR experimental study of five benzimidazoles in solution and in the solid state (13C and 15N CPMAS NMR) as well as the theoretically calculated (GIAO/DFT) chemical shifts. We have assigned unambiguously the "tautomeric positions" (C3a/C7a, C4/C7 and C5/C6) of NH-benzimidazoles that, in some solvents and in the solid state, appear different (blocked tautomerism). In the case of 1H-benzimidazole itself we have measured the prototropic rate in HMPA-d18.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 Libration of phenyl groups detected by VT-SSNMR: Comparison with X-ray crystallography(Wiley, 2018-05-28) Nieto Gómez, Carla Isabel; Cabildo, Pilar; García, María Ángeles; Claramunt, Rosa María; José Elguero; Alkorta, IbonThe X‐ray crystal structure of 2‐benzyl‐1H‐benzimidazole, 2BnBzIm, was determined at 293 K showing no dynamic phenomena (disorder) of any class. On the other hand, some 13 C NMR signals were absent in the CPMAS spectrum (100 MHz, 300 K). We decided to carry out variable‐temperature SSNMR and discovered that the missing signals are ortho and meta carbons of the phe- nyl ring of the benzyl group. Line‐shape analysis and the Eyring equation were used to determine the barrier, which was compared with the calculated DFT for the gas phase that it is much lower.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 Pyrazaboles and pyrazolylboranes(Elsevier, 2022-12-15) Nieto Gómez, Carla Isabel; Claramunt Vallespí, Rosa María; Alkorta, Ibon; Elguero, JoséThe synthesis, reactivity, and properties of pyrazaboles and pyrazolylboranes have been reviewed with special attention to the NMR properties and X-ray structures. 104 X-ray structures are presented and 150 references are cited, which is a significant expansion of previous reviews. It appears that several items are incomplete and others deserve further development indicating than the field of pyrazaboles and of pyrazolylboranes needs new research contributions in particular in the field of coordination chemistry, a field that is clearly underdeveloped.Publicación Effects of Curcuminoid Pyrazoles on Cancer Cells and on the Expression of Telomerase Related Genes(Wiley, 2016-07) Martí Centelles, Rosa; Falomir Ventura, Eva; Carda, Miguel; Cornago, María del Pilar; Claramunt, Rosa María; Nieto Gómez, Carla IsabelA group of 13 curcuminoid pyrazoles was investigated for their cytotoxicity on three tumoral cell lines (HT-29, MCF-7, and HeLa) and one non-tumoral human cell line (HEK-293). The values obtained were compared with those of curcumin. A subset of selected derivatives was also studied for their ability to downregulate expression of the hTERT and c-Myc genes, which are both involved in telomerase activity.Publicación X‑ray Molecular Structures of 23 N1-4-Nitrophenyl, 2,4- Dinitrophenyl, and 2,4,6-Trinitrophenyl-2-pyrazolines(American Chemical Society, 2023-01-03) Torralba, María del Carmen; Nieto Gómez, Carla Isabel; Claramunt Vallespí, Rosa María; Elguero, JoséHerein, we present a complete crystallographic study of three series of N1-aryl substituted-2-pyrazolines, the aryl group being 4-nitrophenyl (series1), 2,4-dinitrophenyl (series2), and 2,4,6-trinitrophenyl (series3). The structural features, bond distances and angles as well as torsions for each single compound will be described and comparatively discussed with data for related heterocycles found in the Cambridge Structural Database (2020.2.0). A deeper look at the data has been achieved to know the influence of the substituents on the molecular structures. In the crystals of compounds with stereogenic centers at positions 4 and 5, the presence of both enantiomers has been encountered in 12 cases out of 14 that include a literature result. Finally, molecular packings in all series have been analyzed reaching the conclusion that they follow several patterns depending on the existence or not, and the type of intermolecular interactions. A general pattern has been observed which implies a certain tendency of the molecules to arrange into chains, whose additional contacts could extend the dimensionality of the networkPublicación 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%.