18 research outputs found

    3-Oxo-hexahydro-1H-isoindole-4-carboxylic acid as a drug chiral bicyclic scaffold and its application to the preparation of conformationally constrained covalent and non-covalent prolyl oligopeptidase inhibitors.

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    Bicyclic chiral scaffolds are privileged motifs in medicinal chemistry. Over the years, we have reported covalent bicyclic prolyl oligopeptidase inhibitors that were highly selective for POP over a number of homologous proteins. Herein, we wish to report the structure-based design and synthesis of a novel class of POP inhibitors based on hexahydroisoindoles. A docking study guided the selection of structures for synthesis. The stereochemistry, decoration, and position within the molecule of the bicyclic scaffolds were assessed virtually. Following the synthesis of the best candidates, in vitro assays revealed that one member of this chemical series was more active than any of our previous inhibitors with a Ki of 1.0 nM. Additional assays also showed that the scaffold of this potent inhibitor, in contrast to one of our previously reported chemical series, is highly metabolically stable, despite the foreseen potential sites of metabolism. Interestingly, computer docking calculations accurately predicted the optimal features of the inhibitors

    Direct determination of the zero-field splitting for the Fe<sup>3+</sup> ion in a synthetic polymorph of NaMgFe(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub>·9H<sub>2</sub>O: A natural metal-organic framework

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    We employed inelastic neutron scattering (INS), specific heat, and magnetization analysis to study the magnetism in a synthetic polymorph of the quasi-two-dimensional natural metal-organic framework material, stepanovite NaMgFe(C2O4)3·9H2O. No long-range magnetic order can be observed down to 0.5 K. The INS spectra show two dispersionless excitations at energy transfer 0.028(1) and 0.050(1) meV at base temperature, which are derived from the magnetic transitions between zero-field splitting (ZFS) of S=5/2 ground state multiplets of Fe3+ ion. Further analysis of the INS results shows that the Fe3+ ion has an easy-axis anisotropy with axial ZFS parameter D=-0.0128(5) meV and rhombic parameter E=0.0014(5) meV. The upward behavior at zero field and Schottky-like peak under magnetic field of the low-temperature magnetic specific heat further support the INS results. Our results clearly reveal the magnetic ground and excited state of this stepanovite polymorph. © 2021 American Physical Society

    Green and rapid mechanosynthesis of high-porosity NU- and UiO-type metal-organic frameworks

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    The use of a dodecanuclear zirconium acetate cluster as a precursor enables the rapid, clean mechanochemical synthesis of high-microporosity metal-organic frameworks NU-901 and UiO-67, with surface areas up to 2250 m2 g-1. Real-time X-ray diffraction monitoring reveals that mechanochemical reactions involving the conventional hexanuclear zirconium methacrylate precursor are hindered by the formation of an inert intermediate, which does not appear when using the dodecanuclear acetate cluster as a reactant. © 2018 The Royal Society of Chemistry
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