José L Alonso

Universidad de Valladolid, Valladolid, Castille and León, Spain

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Publications (138)572.91 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The rotational spectrum of the natural amino acid tryptophan has been observed for the first time using a combination of laser ablation, molecular beams, and Fourier transform microwave spectroscopy. Independent analysis of the rotational spectra of individual conformers has conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The analysis of the 14N nuclear quadrupole coupling constants is of particular significance since it allows discrimination between structures, thus providing structural information on the orientation of the amino group. Both observed conformers are stabilized by an O–H · · ·N hydrogen bond in the side chain and a N–H · · · π interaction forming a chain that reinforce the strength of hydrogen bonds through cooperative effects.
    The Journal of Chemical Physics. 01/2014; 140(20):-.
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    ABSTRACT: Histidine is an important natural amino acid, involved in many relevant biological processes, which, because of its physical properties, proved difficult to characterize experimentally in its neutral form. In this work, neutral histidine has been generated in the gas phase by laser ablation of solid samples and its NεH tautomeric form unraveled through its rotational spectrum. The quadrupole hyperfine structure, arising from the existing three 14N nuclei, constituted a site-specifically probe for revealing the tautomeric form as well as the side chain configuration of this proteogenic amino acid.
    Angewandte Chemie International Edition 01/2014; · 11.34 Impact Factor
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    ABSTRACT: Combined spectroscopy measurements and theoretical calculations bring to light a first investigation of a metallic cyanoacetylide, AlC3N, using laser ablation molecular beam Fourier transform microwave spectroscopy. This molecule was synthesized in a supersonic expansion by the reaction of aluminum vapour with C3N, produced from solid aluminum rods and BrCCCN in a newly constructed ablation-heating nozzle device. A set of accurate rotational and 27Al and 14N nuclear quadrupole coupling constants have been determined from the analysis of the rotational spectrum and compared with those predicted in a high-level ab initio study, conducting to the assignment of the observed species to linear AlCCCN. We have searched for this species towards the carbon-rich evolved star IRC + 10216 but only an upper limit to its abundance has been obtained.
    The Journal of Chemical Physics. 01/2014; 141(10):-.
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    ABSTRACT: A non-conventional vaporization method, using laser ablation of solid NaCl doped with d-erythrose, has been used to bring this sugar into the gas phase for rotational study. The jet cooled rotational spectrum of this C4 monosaccharide reveals the existence of two furanose forms, one α envelope and one β twist. Cooperative hydrogen bond networks and the anomeric effect have been found to be the main stabilization factors of the detected structures.
    Chemical Communications 10/2013; · 6.38 Impact Factor
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    ABSTRACT: Crystalline samples of d-xylose have been vaporized by laser ablation and probed in the gas phase using Fourier transform microwave spectroscopy. The rotational spectrum revealed the existence of two α-d-xylopyranose conformers stabilized by the anomeric effect and cooperative hydrogen bond networks. The experiment spectroscopically tracked fine structural changes upon clockwise and counterclockwise arrangements of the OH groups in the observed conformers. The five monosubstituted (13)C species of the most abundant conformer cc-α-(4)C1 have also been observed in their natural abundance, and its structure has been derived. This work demonstrates the pivotal role that the intramolecular hydrogen-bonding network plays in the conformational behavior of free monosaccharides.
    Physical Chemistry Chemical Physics 09/2013; · 3.83 Impact Factor
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    ABSTRACT: A clear picture of the conformations of isolated 2-deoxy-D-ribose was obtained using chirped pulse and Balle–Flygare Fourier-transform microwave spectrometers, both coupled with laser ablation sources. Two conformers of α-D-deoxyribopyranose and four of β-D-deoxyribopyranose were found on the basis of the spectroscopic rotational parameters and ab initio predictions. The substitution and effective structures of the most abundant conformer have been determined.
    Angewandte Chemie International Edition 09/2013; · 11.34 Impact Factor
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    ABSTRACT: The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier transform microwave spectrometers. The joint experimental-computational study allowed us to determine the accurate molecular structure and spectroscopic properties of the title molecule, but more importantly, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules.
    Physical Chemistry Chemical Physics 09/2013; · 3.83 Impact Factor
  • Carlos Cabezas, Marcelino Varela, José L Alonso
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    ABSTRACT: The small peptide derived from proline, N-acetyl-prolinamide (Ac-Pro-NH2 ), has been investigated using a combination of Fourier transform microwave spectroscopy with laser ablation. Spectral signatures belonging to only one conformer have been detected in the supersonic expansion. Rotational constants and nuclear quadrupole coupling constants of the two (14) N nuclei have been used in the characterization of a γ-turn structure in the gas phase, which is stabilized by a CO⋅⋅⋅HN intramolecular hydrogen bond closing a seven-membered ring. A methyl group internal rotation barrier of 354 cm(-1) has been determined from the analysis of the A-E splittings.
    ChemPhysChem 05/2013; 14:2539-2543. · 3.35 Impact Factor
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    ABSTRACT: The complex of glycine with two water molecules glycine-(H2O)2 has been generated by laser ablation in a supersonic expansion and characterised using rotational spectroscopy. The water molecules bind to the carboxylic group of glycine and to each other through three intermolecular hydrogen bonds, closing an eight-membered ring. In the complex, glycine adopts the conformation found to be the most stable for bare glycine.
    Chemical Communications 03/2013; · 6.38 Impact Factor
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    ABSTRACT: Two conformers of D-fructopyranose are characterized using laser ablation and broadband Fourier-transform microwave spectroscopy. Both species are stabilized by complicated intramolecular hydrogen-bonding networks. Structural motifs related to the sweetness of D-fructopyranose are revealed for the most stable conformer.
    ChemPhysChem 02/2013; · 3.35 Impact Factor
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    ABSTRACT: Microwave spectroscopy has been applied to characterize the conformations adopted in the gas phase by a small peptide derived from alanine, N-acetyl-L-alaninamide (Ac-Ala-NH2). This compound was vaporized by laser ablation and shown to exist as a mixture of Ceq7 and C5 conformers stabilized by a COHN intramolecular hydrogen bond closing a seven- or a five-membered ring, respectively. The complicated quadrupole hyperfine structure originated from two 14N nuclei has been completely resolved for both species and the derived nuclear quadrupole coupling constants have been used to determine the Ramachandran angles that describe their molecular shapes.
    Physical Chemistry Chemical Physics 01/2013; 15(7). · 3.83 Impact Factor
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    ABSTRACT: Give me five! All five tautomers and conformers of cytosine were characterized in the gas phase by laser ablation molecular beam Fourier transform microwave spectroscopy. The spectra were assigned unambiguously on the basis of the hyperfine structure due to the three (14) N nuclei (see picture; N blue, O red). The relative energies of the identified species were estimated from the relative intensities of the spectra.
    Angewandte Chemie International Edition 01/2013; · 11.34 Impact Factor
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    ABSTRACT: Microwave spectroscopy has been applied to characterize the conformations adopted in the gas phase by a small peptide derived from alanine, N-acetyl-l-alaninamide (Ac-Ala-NH(2)). This compound was vaporized by laser ablation and shown to exist as a mixture of C and C(5) conformers stabilized by a COHN intramolecular hydrogen bond closing a seven- or a five-membered ring, respectively. The complicated quadrupole hyperfine structure originated from two (14)N nuclei has been completely resolved for both species and the derived nuclear quadrupole coupling constants have been used to determine the Ramachandran angles that describe their molecular shapes.
    Physical Chemistry Chemical Physics 01/2013; · 3.83 Impact Factor
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    ABSTRACT: The rotational spectrum of neutral dopamine has been investigated for the first time using a combination of Fourier transform microwave spectroscopy with laser ablation. The parameters extracted from the analysis of the spectrum unequivocally identify the existence of seven conformers of dopamine. 14N nuclear quadrupole coupling interactions have been used to determine the orientation of the amino group probing the existence of stabilizing N–H···π interactions for all observed conformers.
    Journal of Physical Chemistry Letters 01/2013; 4(3):486-490. · 6.59 Impact Factor
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    ABSTRACT: Fast-passage Fourier transform microwave spectroscopy in combination with a laser ablation source has been successfully applied to probe vitamin C (l-ascorbic acid) in the gas phase. Its ethyldiol side chain and two hydroxyl groups around the γ-lactone ring provide five internal rotation axes, enabling vitamin C to assume a wide variety of nonplanar 3D cooperative hydrogen bond networks that can also include the keto and ether functions. The rotational constants extracted from the analysis of the spectrum unequivocally identify the existence of three dominant conformers stabilized by different intramolecular hydrogen bonding motifs forming five-, six-, or seven-membered rings.
    Journal of Physical Chemistry Letters 01/2013; 4(1):65-69. · 6.59 Impact Factor
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    ABSTRACT: Ein klares Bild von den Konformationen isolierter 2‐Deoxy‐D‐ribose wurde mithilfe von Chirped‐Puls‐ und Balle‐Flygare‐Fourier‐Transformations‐Mikrowellenspektrometrie jeweils in Kombination mit Laserablationsquellen erhalten. Zwei Konformere der α‐D‐Deoxyribopyranose und vier der β‐D‐Deoxyribopyranose wurden auf Basis der spektroskopischen Rotationsparameter und von Ab‐initio‐Rechnungen identifiziert. Das Substitutionsmuster und die effektiven Strukturen der häufigsten Konformere wurden bestimmt.
    Angewandte Chemie 01/2013; 125(45).
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    ABSTRACT: A laser ablation device in combination with a molecular beam Fourier-transform microwave spectrometer has allowed the observation of the rotational spectrum of serotonin for the first time. Three conformers of the neurotransmitter have been detected and characterized in the 4-10 GHz frequency range. The complicated hyperfine structure arising from the presence of two (14)N nuclei has been fully resolved for all conformers and used for their identification. Nuclear quadrupole coupling constants of the nitrogen atom of the side chain have been used to determine the orientation of the amino group probing the existence of N-Hπ interactions involving the amino group and the pyrrole unit in the Gauche-Phenyl conformer (GPh) or the phenyl unit in the Gauche-Pyrrole (GPy) ones.
    Physical Chemistry Chemical Physics 09/2012; 14(39):13618-23. · 3.83 Impact Factor
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    ABSTRACT: The rotational spectra of β-propiolactone-(H_2O)_n (n=1-5) adducts have been extensively analyzed by broadband microwave spectroscopy (CP-FTMW). Unambiguous identification of their structures has been achieved from the spectra of the parent species and H_218O single substitution clusters and Stark effect measurements. In addition to our previous work, the substitution structures for two n=4 and one n=5 complexes are presented. The three structures show a cyclic arrangement in the oxygen framework. For both n=4 structures, the water molecules form a quasiplanar ring that sits above the BPL unit. The structural differences between these two n=4 complexes are discussed in terms of the water oxygen atom positions and dipole moment orientations, enabling to distinguish between isomers with certainty by CP-FTMW spectroscopy. For n=5, a cyclic arrangement similar to n=4 was found with water molecules making a puckered five-water ring. Substitution coordinates for the oxygen framework support the assignment. Our results show that complexation with BPL induces measurable structural changes in the (H_2O)_n (n = 3, 4, 5) pure water clusters. This fact is also discussed in terms of the variation in O-O distances within pure and complexed water clusters.
    06/2012;
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    ABSTRACT: One dominant structure has been identified analysing the rotational spectrum of asparagine in sharp contrast with the multiconformational behaviour for other amino acids with polar side chains. This locking of the conformational variety to a single conformer has been ascribed to an intramolecular hydrogen bonding network involving α-amine, α-carboxylic and amide groups.
    Chemical Communications 05/2012; 48(47):5934-6. · 6.38 Impact Factor
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    ABSTRACT: The first high-resolution study of isolated gas-phase acetyl salicylic acid (aspirin) is reported. Solid aspirin was vaporized by laser ablation, expanded in a supersonic jet, and characterized by Fourier transform microwave spectroscopy (see picture). Two different neutral structures have been identified from the analysis of the rotational spectrum.
    Angewandte Chemie International Edition 02/2012; 51(6):1375-8. · 11.34 Impact Factor

Publication Stats

743 Citations
572.91 Total Impact Points

Institutions

  • 1979–2014
    • Universidad de Valladolid
      • Facultad de Ciencias
      Valladolid, Castille and León, Spain
  • 2006–2013
    • University of Bologna
      • "Giacomo Ciamician" Department of Chemistry CHIM
      Bologna, Emilia-Romagna, Italy
  • 2011
    • University of Zaragoza
      • Department of Organic Chemistry
      Zaragoza, Aragon, Spain
  • 2002
    • Shizuoka University
      • Department of Chemistry
      Shizuoka-shi, Shizuoka-ken, Japan