Recent works has showed that minerals composed by oxide semiconductor (e.g. hematite, Fe2O3) played an important role in prebiotic organic synthesis, mainly because their optical properties, physical and chemical adsorption, as well as catalytic properties. In order to verify the influence of hematite on the synthesis of organic molecules, in this work we investigated the electrochemistry of a Fe2O3-modified FTO (Fluorine-doped tin oxide) electrode in the presence of thiocyanate ions (SCN-), a molecule formed from prebiotic gases reaction in the early Earth atmosphere. The experiments were carried out at pH 6.8 (prebiotic ocean conditions), where changes on the peak potential (-0.6 V) related to pseudo-capacitive processes for hematite were observed; thus, SCN- interacts with hematite surface. In another experiment, a SCN- solution was irradiated during five hours, by using a 450 W UV lamp, where a white precipitate was obtained. The latter was analyzed by FTIR and S - H groups was found as product, indicated a possible formation of thiomethyl (CH3SH). This bond is a precursor for sulfur amino acids in prebiotic syntheses, e.g. methionine. Furthermore, we can infer that the presence of UV light is important for prebiotic molecules synthesis and the hematite can be used as catalyst for thiocyanate reactions. Based in these results, a conjugated system based on electrochemistry and UV absorption is under investigation.

Photo and electrochemical reaction of thiocyanate in the presence of hematite in prebiotic conditions

247th National Meeting (2014)

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