Thermally Induced Single-Crystal-to-Single-Crystal Transformation and Heterogeneous Catalysts for Epoxidation Reaction of Co(II) Based Metal–Organic Frameworks Containing 1,4-Phenylenediacetic Acid

Four new metal–organic frameworks (MOFs) based on 1,4-phenylenediacetic acid (1,4-H₂phda), [Co­(1,4-phda)­(4,4′-bpa)] (<b>1</b>), [Co­(1,4-phda)­(4,4′-bpp)] (<b>2</b>), [Co­(1,4-phda)­(4,4′-bpa)­(H₂O)₂] (<b>3</b>), and [Co­(1,4-phda)­(4,4′-bpa)] (<b>3a</b>) (4,4′-bpa = 1,2-bis­(4-pyridyl)­ethane and 4,4′-bpp = 1,3-bis­(4-pyridyl)­propane) were successfully synthesized. The various synthetic methods play an important role in the formation of diverse structural frameworks. Compound <b>1</b> shows a 3D framework, while <b>2</b>, <b>3</b>, and <b>3a</b> exhibit 2D layered MOFs with different architectures. The irreversible thermally induced single-crystal-to-single-crystal transformation with chromotropism from <b>3</b> to <b>3a</b> was observed, which was established by the breakage and reformation of coordination bonds around Co­(II) centers. The orientation of coordinated 4,4′-bpa ligand and conformation of 1,4-phda ligand play a key role on pore opening in <b>3</b> and pore closing in <b>3a</b>. Furthermore, the functional properties as heterogeneous catalysts of these MOFs including epoxidation of alkenes and photocatalytic performance for MB degradation have been investigated. The heterogeneous catalytic properties of <b>1</b>, <b>2</b>, and <b>3a</b> exhibit high catalytic activity with good catalyst stability

Hypoxylonone, a new oxa-bridged seven-membered ring analog from fungus <i>Hypoxylon</i> cf. <i>subgilvum</i> SWUF15-004

A new oxa-bridged seven-membered ring analog, hypoxylonone (1), and thirteen known compounds (2–14) were isolated from fungus Hypoxylon cf. subgilvum SWUF15-004. The structures were elucidated by the analysis of spectroscopic (IR, 1 D and 2 D NMR), HRESIMS and X-ray diffraction (MoKα) data. Several isolated compounds were evaluated for cytotoxicity against four human cancer cell lines (HeLa, HT29, MCF-7, A549). Compound 1 exhibited weak inhibitory effects of the nitric oxide production in RAW264.7 cells. Compounds 8 and 9 exhibited slight cytotoxicity.</p

A Series of Cyanoacetato Copper(II) Coordination Polymers with Various <i>N</i>,<i>N</i>′‑Ditopic Spacers: Structural Diversity, Supramolecular Robustness, and Magnetic Properties

Five novel copper­(II) coordination polymers containing cyanoacetate (cna) anion with various <i>N</i>,<i>N</i>′-ditopic spacers [Cu­(cna)₂­(pyz)]_<i>n</i> (<b>1</b>), [Cu­(cna)₂­(bpy)­(H₂O)₂]_<i>n</i> (<b>2</b>), [Cu­(cna)₂­(dpe)]_<i>n</i> (<b>3</b>), [Cu­(cna)₂­(dpe)]_<i>n</i>­(H₂O)_<i>n</i> (<b>4</b>), and [Cu­(cna)₂­(bpa)]_<i>n</i> (<b>5</b>) (when pyz = pyrazine, bpy = 4,4′-bipyridyl, dpe = 1,2-di­(4-pyridyl)­ethylene, and bpa = 1,2-di­(4-pyridyl)­ethane) were structurally and spectroscopically characterized. Compound <b>1</b> shows a two-dimensional (2D) sheet structure constructed from μ₂-1,3­(<i>syn,anti</i>) coordinative mode of cyanoacetate and μ₂-pyz linking adjacent Cu­(II) centers. Compound <b>2</b> exhibits a one-dimensional (1D) polymeric chain which is formed by μ₂-bpy bridging between [Cu­(cna)₂­(H₂O)₂] units, whereas compounds <b>3</b>–<b>5</b> reveal 1D ladder-like structures which are built from double-μ₂-dpe/bpa spacers connecting neighboring Cu­(II) cyanoacetate dimers. Weak interactions such as hydrogen bonding and N<i>···π</i> and/or C–H<i>···π</i> interactions join the adjacent layers of <b>1</b> or polymeric chains of <b>2</b>–<b>5</b> to stabilize overall supramolecular networks. The thermal stabilities of <b>1</b>–<b>5</b> were investigated. Interestingly, compound <b>2</b> reveals a robust supramolecular framework constructed by 1D polymeric chains during thermal dehydration and rehydration processes, which has been further verified by spectroscopic techniques, elemental analyses, thermogravimetric analysis, and X-ray powder diffraction. Moreover, this behavior is not observed in the isomorphous series containing Co­(II) and Ni­(II) ions. The magnetic properties of <b>1</b> and <b>3</b> exhibit very weak antiferromagnetic interactions between Cu­(II) centers