Mononuclear nickel complexes bioinspired by hydrogenases as catalysts for hydrogen production

LEDESMA, G.N.

Bento Goncalves

Congreso; XX Brazilian Meeting on Inorganic Chemistry; 2022

Comité Organizador do XX BMIC

Hydrogenases constitute a family of metalloenzymes that interconvert protons and electrons with hydrogen [2H+ + 2e- ↔ H2] in an efficient and clean way, therefore hydrogenases are capable of generating H2.1 Heterodinuclear [NiFe] hydrogenases represent the most abundant group and their redox chemistry is concentrated on the nickel ion, while the iron remains in the +II oxidation state.2 Based on the nickel-centered mechanism of [NiFe] hydrogenases, one of the research approaches is focused on the study of biomimetic compounds. This has served to provide minimalistic models where the use of mononuclear nickel complexes is considered relevant, for their subsequent evaluation as catalysts in hydrogen production. Thus, the development and improvement of synthetic hydrogenases mimetics, capable to emulate their functionality under conditions where their stability is conserved, constitutes an important task.With this aim, the synthesis of new mononuclear nickel complexes derived from ’-thiophene-dithiosemicarbazone ligands is presented. These complexes were characterized and evaluated as hydrogenase models. Additionally, they were also used to prepare TiO2-based composites, which were analyzed by spectroscopic techniques (energy-dispersive X-ray spectroscopy, Raman spectroscopy) and powder X-ray diffraction.By performing the evaluation of the catalytic activity of the respective composites, our results show that these hybrid systems are stable under the assayed conditions, and validate the feasibility of our mononuclear nickel complexes to photocatalyse H2 production, even after prolonged irradiation periods.