Multivariable sieving is realized on the basis of a series of isostructural metalorganic frameworks, MIL-140s [ZrO(O 2 C-R-CO 2)], with triangular hydrophobic channels. MIL-140s enable multivariable sieving of dyes and practical toxics, such as high carcinogenic pesticides and persistent organic pollutants. The sieving mechanisms are revealed through presenting an outside-in theoretical model, hierarchical recognition, by the regulation of surface charge, pore size, and potential energy surface of MIL-140s.
3-(1,2,4-Triazol-4-yl)adamantane-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 MoVI oxide organic hybrid. The ligand
crystallized from water as tradcH·H2O (1), possessing a two-dimensional hydrogen-bonding network, and from
ethanol as a cyclic molecular solvate with the composition (tradcH)3·2EtOH (2). Treatment of tradcH with MoO3 under hydrothermal conditions afforded a new Mo trioxide
hybrid, [MoO3(tradcH)]·H2O (3), which was structurally characterized. In 3, the molybdenum
atoms form a polymeric zigzag chain of {μ2-O-MoO2}
n
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 °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.
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