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Garcia-Iriepa C.,University of Alcala | Marazzi M.,University of Alcala | Frutos L.M.,University of Alcala | Sampedro D.,Research Center en Sintesis Quimica
RSC Advances | Year: 2013

Molecular switches based on E/Z photoisomerization have been used in different contexts in order to control a variety of processes in different systems, from peptide conformation control to molecular data storage devices, from catalysis to smart materials. The syntheses, properties and applications of several types of E/Z photochemical switches are presented with special attention paid to azobenzenes, overcrowded alkenes and switches based on the protonated Schiff base chromophore of rhodopsins. © 2013 The Royal Society of Chemistry. Source

Rivero D.,University of Alcala | Valentini A.,University of Alcala | Valentini A.,University of Siena | Fernandez-Gonzalez M.A.,University of Alcala | And 6 more authors.
Journal of Chemical Theory and Computation | Year: 2015

Photoreactivity can be influenced by mechanical forces acting over a reacting chromophore. Nevertheless, the specific effect of the external forces in the photoreaction mechanism remains essentially unknown. Conical intersections are key structures in photochemistry, as they constitute the funnels connecting excited and ground states. These crossing points are well known to provide valuable information on molecular photoreactivity, including crucial aspects as potential photoproducts which may be predicted by just inspection of the branching plane vectors. Here, we outline a general framework for understanding the effect of mechanical forces on conical intersections and their implications on photoreactivity. Benzene S1/S0 conical intersection topology can be dramatically altered by applying less than 1 nN force, making the peaked pattern of the intersection become a sloped one, also provoking the transition state in the excited state to disappear. Both effects can be related to an increase in the photostability as the conical intersection becomes more accessible, and its topology in this case favors the recovery of the initial reactant. The results indicate that the presence of external forces acting over a chromophore have to be considered as a potential method for photochemical reactivity control. © 2015 American Chemical Society. Source

Garcia-Iriepa C.,University of Alcala | Garcia-Iriepa C.,Research Center en Sintesis Quimica | Marazzi M.,University of Alcala | Zapata F.,University of Alcala | And 3 more authors.
Journal of Physical Chemistry Letters | Year: 2013

Generation of a chiral hydrogen bond environment in efficient molecular photoswitches is proposed as a novel strategy for the design of photoactive molecular motors. Here, the following strategy is used to design a retinal-based motor presenting singular properties: (i) a single excitation wavelength is needed to complete the unidirectional rotation process (360); (ii) the absence of any thermal step permits the process to take place at low temperatures; and (iii) the ultrafast process permits high rotational frequencies. © 2013 American Chemical Society. Source

Lopez-Rituerto E.,Research Center en Sintesis Quimica | Avenoza A.,Research Center en Sintesis Quimica | Busto J.H.,Research Center en Sintesis Quimica | Peregrina J.M.,Research Center en Sintesis Quimica
Journal of Agricultural and Food Chemistry | Year: 2010

Because the metabolite transformations in wine fermentation processes play a crucial role in the organoleptic and hygienic quality of wines, the nuclear magnetic resonance (NMR) technique is presented as a significant tool to follow metabolic pathways. In this paper, we investigated the transformation of several amino acids into their corresponding higher alcohols during the alcoholic fermentation, showing that the amino acids are totally consumed in the first stages of the process. © 2010 American Chemical Society. Source

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