Examinando por Autor "Vega, Jorge"

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Ammonium affects the wet chemical network of HCN: feedback between prebiotic chemistry and materials science
(Royal Society of Chemistry, 2023-06-21) De la Fuente, J. L.; Vega, Jorge; Mateo Martí, Eva; Valles González, M. P.; Ruiz Bermejo, Marta; Pérez Fernández, Cristina; Instituto Nacional de Técnica Aeroespacial (INTA); Universidad Complutense de Madrid (UCM); Agencia Estatal de Investigación (AEI); Consejo Superior de Investigaciones Científicas (CSIC); Ministerio de Ciencia, Innovación y Universidades (MICINN)
Prebiotic chemistry one-pot reactions, such as HCN-derived polymerizations, have been used as stimulating starting points for the generation of new multifunctional materials due to the simplicity of the processes, use of water as solvent, and moderate thermal conditions. Slight experimental variations in this special kind of polymerization tune the final properties of the products. Thus, herein, the influence of NH4Cl on the polymerization kinetics of cyanide under hydrothermal conditions and on the macrostructures and properties of this complex system is explored. The kinetics of the process is consistent with an autocatalytic model, but important variations in the polymerization reaction are observed according to a simple empirical model based on a Hill equation. The differences in the kinetic behaviour against NH4Cl were also revealed when the structural, morphological, thermal, electronic and magnetic properties of the synthesized cyanide polymers were compared, and these properties were evaluated by elemental analysis, FTIR, XPS, UV-vis, and ESR spectroscopies, X-ray diffraction, SEM and thermoanalytical techniques. As a result, this hydrothermal prebiotic polymerization is not only pH dependent, as previously thought, but also ammonium subservient. From this result, a hypothetical reaction mechanism was proposed, which involves the active participation of ammonium cations via formamidine and serves as a remarkable point against previous reports. The results discussed here expand the knowledge on HCN wet chemistry, offer an extended view of the relevant parameters during the simulation of hydrothermal scenarios and describe the production of promising paramagnetic and semiconducting materials inspired by prebiotic chemistry.
Acceso Abierto
Prebiotic synthesis of noncanonical nucleobases under plausible alkaline hydrothermal conditions
(Springer Nature, 2022-09-07) Pérez Fernández, Cristina; Vega, Jorge; Rayo Pizarroso, P.; Mateo Martí, Eva; Ruiz Bermejo, Marta; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Ministerio de Ciencia, Innovación y Universidades (MICIN); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Herein, the potential of alkaline hydrothermal environments for the synthesis of possible ancestral pre-RNA nucleobases using cyanide as a primary source of carbon and nitrogen is described. Water cyanide polymerizations were assisted by microwave radiation to obtain high temperature and a relatively high pressure (MWR, 180 °C, 15 bar) and were also carried out using a conventional thermal system (CTS, 80 °C, 1 bar) to simulate subaerial and aerial hydrothermal conditions, respectively, on the early Earth. For these syntheses, the initial concentration of cyanide and the diffusion effects were studied. In addition, it is well known that hydrolysis conditions are directly related to the amount and diversity of organic molecules released from cyanide polymers. Thus, as a first step, we studied the effect of several hydrolysis procedures, generally used in prebiotic chemistry, on some of the potential pre-RNA nucleobases of interest, together with some of their isomers and/or deamination products, also presumably formed in these complex reactions. The results show that the alkaline hydrothermal scenarios with a relatively constant pH are good geological scenarios for the generation of noncanonical nucleobases using cyanide as a prebiotic precursor.