A hydrogen-bonded assembly of cucurbit[6]uril and [MoO2Cl2(H2O)(2)] with catalytic efficacy for the one-pot conversion of olefins to alkoxy products
authors Nogueira, LS; Antunes, MM; Gomes, AC; Cunha-Silva, L; Pillinger, M; Lopes, AD; Valente, AA; Goncalves, IS
nationality International
journal DALTON TRANSACTIONS
keywords CAMBRIDGE STRUCTURAL DATABASE; OXO-MOLYBDENUM COMPLEXES; CRYSTAL-STRUCTURES; EFFICIENT CATALYSTS; OXIDATION; COORDINATION; CUCURBITURIL; CYCLOHEXENE; STYRENE; EPOXIDATION
abstract The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoO2Cl2(H2O)(2)] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoO2Cl2(H2O)(2)]center dot CB[6]center dot xH(2)O center dot yHCl center dot z(CH3COCH3) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entities, {CB[6]center dot 10(H2O)}, aligned in layers which are shifted relative to adjacent layers to form a brick-like pattern. The CB[6]/water hydrogen-bonded entities further engage in intermolecular interactions with water, HCl and [MoO2Cl2(H2O)(2)] molecules to form a three-dimensional (3D) framework. Compound 2 was characterised by thermogravimetric analysis (TGA), IR and Raman vibrational spectroscopy, and C-13{H-1} CP MAS NMR. The reference complex [MoO2Cl2(H2O)(2)]center dot(diglyme)(2) (1) and compound 2 were studied for the oxidative catalytic conversion of olefins (cis-cyclooctene, cyclohexene and styrene) with aqueous H2O2 as oxidant. Using alcohols as solvents, 2 was employed in a one-pot two-stage strategy for converting olefins to alkoxy products, which involves oxidation (with H2O2) and acid chemistry. Mechanistic studies were carried out using different intermediates as substrates, and the type of solvent and substrate scope were investigated. The results demonstrated the ability of the CB[6]/Mo-VI supramolecular adduct to function as an acid-oxidation multifunctional catalyst, and its recovery and reuse via relatively simple procedures.
publisher ROYAL SOC CHEMISTRY
issn 1477-9226
year published 2019
volume 48
issue 30
beginning page 11508
ending page 11519
digital object identifier (doi) 10.1039/c9dt02127b
web of science category Chemistry, Inorganic & Nuclear
subject category Chemistry
unique article identifier WOS:000477957200032

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