A Molybdenum Trioxide Hybrid Decorated by 3-(1,2,4-Triazol-4-yl)adamantane-1-carboxylic Acid: A Promising Reaction-Induced Self-Separating (RISS) Catalyst

abstract

3-(1,2,4-Triazol-4-yOadamantane-1-carboxylic acid (tradcH), a heterobifunctional organic ligand in which carboxylic acid and 1,2,4-triazole groups are united through a rigid 1,3-adamantanediyl spacer, was employed for the synthesis of a Mo-VI oxide organic hybrid. The ligand crystallized from water as tradcH center dot H2O (1), possessing a two-dimensional hydrogen-bonding network, and from ethanol as a cyclic molecular solvate with the composition (tradcH)(3)center dot 2EtOH (2). Treatment of tradcH with MoO3 under hydrothermal conditions afforded a new Mo trioxide hybrid, [MoO3(tradcH)]center dot H2O (3), which was structurally characterized. In 3, the molybdenum atoms form a polymeric zigzag chain of {mu(2)-O-MoO2} which is supported by double triazole bridges, while the carboxylic acid termini are left uncoordinated. The coordination environment of the Mo centers appears as distorted cis-{MoN2O4} octahedra. The hybrid exhibits high thermal stability (up to 270 degrees C) and was employed for a relatively broad scope of catalytic oxidation reactions in the liquid phase. Its catalytic behavior may be compared to a reversible mutation, featuring the best sides of homogeneous and heterogeneous catalysis. The original solid material converts into soluble active species, and the latter revert to the original material upon completion of the catalytic reaction, precipitating and allowing straightforward catalyst separation/reuse (like a heterogeneous catalyst). This catalyst was explored for a chemical reaction scope covering sulfoxidation, oxidative alcohol dehydrogenation, aldehyde oxidation, and olefin epoxidation, using hydrogen peroxide as an eco-friendly oxidant that gives water as a coproduct.

keywords

TRIAZOLYLMOLYBDENUM(VI) OXIDE HYBRIDS; STRUCTURAL ELUCIDATION; OLEFIN EPOXIDATION; DIOXOMOLYBDENUM(VI) COMPLEXES; OXIDATIVE DESULFURIZATION; CYCLOOCTENE EPOXIDATION; CRYSTAL-STRUCTURES; HYDROGEN-PEROXIDE; COORDINATION; PERFORMANCE

subject category

Chemistry

authors

Lysenko, AB; Senchyk, GA; Domasevitch, KV; Henfling, S; Erhart, O; Krautscheid, H; Neves, P; Valente, AA; Pillinger, M; Goncalves, IS

Groups

G1 - Porous Materials and Nanosystems
G4 - Renewable Materials and Circular Economy

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2019)

Conversao catalitica de olefinas derivadas da biomassa (BiOle_AcidOxCat)

acknowledgements

The Portuguese group acknowledges the support provided within the project CICECO-Aveiro Institute of Materials, FCT (Fundacao para a Ciencia e a Tecnologia) ref UID/CTM/50011/2019, financed by national funds through the FCT/MCTES, and the project POCI-01-0145-FEDER-030075, cofunded by POCI (Programa Operacional Competitividade e Internacionalizacao), FEDER (Fundo Europeu de Desenvolvimento Regional), and FCT. P.N. is grateful for support via national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23, of the Decree -Law 57/2016 of August 29, changed by Law 57/2017 of July 19. This work was also supported by the Ministry of Education and Science of Ukraine (Project No. 19BF037-05).