Síntesis y caracterización de compuestos biomimeticos de molibdeno con ligantes nitrogenados polidentados

Abstract

The efficiency of terrestrial ecosystems is limited due to low nutrient availability. For plants, nitrogen (N) availability is one of the main limiting factors in crop yield. Denitrification is the most important process for the nitrogen cycle, since it returns the nitrogen fixed to the atmosphere by microbial respiration processes, it also involves the assimilatory reduction of nitrite to convert it into ammonium and incorporate it into cell metabolism. Therefore, in this work three ligands (L1, L2, L3) were synthesized from the reaction between an amine and an aldehyde, these ligands were reacted with bis(acetylacetonate) dioxomolybdenum (VI) as a source of molybdenum. As a result of these reactions, three compounds were obtained (Mo-L1, Mo-L2, Mo-L3) which were synthesized with the aim of obtaining a coordination compound that presents a metal center with available electrons and a labile ligand that can be easily substituted. In the characterization, spectroscopy techniques were used to identify strain and stress vibrational bands, specific to the different functional groups, the magnetic characteristics of the complexes were obtained, as well as the redox potentials were determined by means of electrochemical techniques. By means of the characterization it was possible to determine the compound that presented the expected characteristics for a biomimetic molybdenum compound with polydentate ligands. The Mo-L3 complex in the IR (infrared spectroscopy) characterization presented vibrational bands at 894 and 914 cm-1 characteristic of a Mo = O bond, in the UV-Vis (Ultraviolet-visible spectroscopy) characterization it did not present any electronic transition signal, which proved that a coordination complex was obtained with a Molybdenum metallic center with oxidation state VI, Therefore, an EPR (Electron paramagnetic resonance) analysis was performed with this complex to verify the initial oxidation state of Molybdenum, and to demonstrate that by adding an electric potential, it is possible to obtain a complex with a Molybdenum species in oxidation state V.