Manuel Montejo

The molecular structure and solution-state molecular interactions in the popular non-steroidal anti-inflammatory drug, ketoprofen, are extensively studied with the aim of gaining a better understanding of the chemical behavior of its solution state and its connection to its nucleation pathway and crystallization outcome. Using as reference solid-state X-ray structures of enantiomeric and racemic forms of ketoprofen, a set of self-assembly models underpinned by density functional theory calculations has been considered for the analysis of spectroscopic data, infrared (IR) and vibrational circular dichroism (VCD), obtained for solutions of the samples as a function of composition and solvent. From our results it can be concluded that, contrary to the general belief for generic carboxylic acids, there are no cyclic dimeric structures of ketoprofen present in solution, but rather linear arrays made up of two (in high polar or diluted media) or more units (in low polar or low dilution media). This observation is in line with the idea that the weak contacts (other than H-bonding) would hold the key to molecular self-assembly, in agreement with recent studies on other aromatic carboxylic acids.

El estudio tuvo como objetivo la exploración de las posibles relaciones entre el desarrollo lingüístico de los profesionales en formación, sus habilidades para el procesamiento de la información científica y la construcción de paquetes de información resultantes. Los métodos fundamentales empleados fueron el análisis y síntesis de la bibliografía relacionada con la historia de los estudios lingüísticos y la búsqueda bibliográfica, así como el estudio de tres tesis doctorales centradas en la interpretación de la lectura, el desarrollo de competencias informacionales y la comprensión de conjuntos textuales. El resultado explica la conexión entre la competencia discursiva, la gestión de la información y los paquetes de información

The synthesis of a series of vinylated analogs of sphingosine-1-phosphate, together with their unambiguous configurational assignment by VCD methods is reported. Among them, compound RBM10-8 can irreversibly inhibit human sphingosine 1 phosphate lyase (hS1PL), while behaving also as an enzyme substrate. These findings, together with the postulated mechanism for S1PL activity, reinforce the role of RBM10-8 as a new mechanism-based hS1PL inhibitor.

The knowledge and dissemination of the Iberian culture (6th to 1st century BC) have made great progress within the last three decades, so much so that it is now one of the main fields in the study of the Protohistory of the Iberian Peninsula. Even so, certain topics remain which need further research in Iberian Archaeology, such as the processes of manufacturing and decoration of various kinds of materials, and the choice of raw materials, including pigments. This piece of research presents micro‐Raman spectroscopy analysis of a set of materials dated between the sixth and the third century BC. The typology of these materials includes ceramics and coverings with and without decoration. All of them are located in various archaeological sites of the Spanish provinces of Jaén, Granada, Málaga and Ciudad Real. The use of micro‐Raman spectroscopy together with energy dispersive X‐ray fluorescence and X‐ray diffraction helped identify gypsum as the main raw material used for the inside coverings of houses and tombs, as well as for storage structures. Less frequent raw materials are calcite, dolomite and quartz. As to decoration in ceramics, the origin and elaboration of black decoration are here identified for the first time in the history of Iberian culture. Black decoration can be classified as two periods: the older period used manganese oxide and the later period used magnetite. Cinnabar has also been identified in the red decoration of ceramics retrieved as grave goods. Copyright © 2016 John Wiley & Sons, Ltd.

The hydrogen‐bond‐assisted self‐association process of a chiral semirigid carboxylic acid, namely, (+)‐(S)‐ketopinic acid, has been studied. The multiconformational monomer/dimer equilibrium has been evaluated by means of a concentration‐dependent FTIR study that enabled the experimental equilibrium constants of the dimer formation reaction (K_dim) to be determined in two solvents of different polarity. In CDCl₃, dimeric forms predominate, even in diluted solutions ( =5.074), whereas in CD₃CN the self‐association process is hindered and monomers are always the main species, irrespective of solute concentration ( =0.194). The reliability of the dimerization constants and the derived mono‐ and dimeric experimental fractions have been proven by means of accurate matching between the experimental vibrational circular dichroism spectra of the species and the theoretical spectra generated by considering the simultaneous weighted contributions of the concomitant monomers and dimers.

The anomeric effect accounts for the greater thermodynamic stability of axially arranged six‐membered heterocycles holding an electronegative substituent at the C1 position. Within a frame of no general consensus, two different theories are typically claimed to justify this effect mostly based on either hyperconjugative or electrostatic factors. Here we report a theoretical‐experimental study of the role of both as anomeric triggers in two archetypical 1,4‐dioxane derivatives, using a suitable combination of spectroscopic (IR and vibrational circular dichroism) and computational techniques for the analysis of the solvation environment effect in their anomeric choices. VCD and IR spectroscopies are used as conformer‐discriminating tools: a detailed analysis of the evolution of the spectral profiles allows assessing the theoretically predicted changes in the experimental α/β ratios when changing the polar solvent, which are fully explained on the basis of an extensive NBO energy partition scheme that provides a detailed view of the role of hyperconjugative and electrostatic interactions as anomeric regulators. Our results suggest that the anomeric equilibrium cannot be described by a single stereoelectronic effect but by the combined contribution of hyperconjugation and electrostatic repulsions, so that the β‐anomeric choice in polar solvents is markedly driven by the strong attenuation of electrostatic repulsive interactions that occurs in solution.

Thermochemical kinetics of hydrolysis reactions of compounds with transannular intramolecular M…N bonds, i.e., atranes RM(OCH₂CH₂)₃N and ocanes R₂M(OCH₂CH₂)₂NH (M = Si, Ge; R = F, Cl, Me), is studied at the B3LYP/aug-cc-pVDZ theoretical level. Several DFT methods are assessed for the reproduction of the experimental activation barrier for the Si-O bond cleavage of 1-methylsilatrane. Activation barriers for atranes and ocanes show the tendency for their growth with the decrease of the electronegativity of a substituent R on going from F to Me and their decrease from Si to Ge. Hydrolysis activation barriers of atranes and ocanes are compared with those of their acyclic analogs RM(OCH₃)₃ and R₂M(OCH₂)₂NH in order to study the role of transannular M…N bonds in the stability of these molecules to hydrolysis. Substantially larger barriers for atranes support the opinion that stability of atranes may be explained by the formation of intramolecular bonds; however, the strengthening of transannular M…N bonds results in lower M-O cleavage barriers. It was proposed that the M-O cleavage barrier height is determined not by a weak M…N bonding itself, but rather by the contribution of a nitrogen lone pair to the antibonding orbitals of M-O bonds. The NBO analysis show that this interaction increases with the decrease of the electronegativity of a substituent R and decreases on going from atranes to ocanes. In ocanes, the presence of M…N bonds does not kinetically hinder the hydrolytic process; M-O cleavage activation barriers for acyclic analogs are higher. M-Hal cleavage barriers are substantially higher than those for M-O cleavage for R = F, but lower for R = Cl.