11 research outputs found
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-H<sub>2</sub>phda), [CoÂ(1,4-phda)Â(4,4′-bpa)] (<b>1</b>), [CoÂ(1,4-phda)Â(4,4′-bpp)] (<b>2</b>), [CoÂ(1,4-phda)Â(4,4′-bpa)Â(H<sub>2</sub>O)<sub>2</sub>] (<b>3</b>), and [CoÂ(1,4-phda)Â(4,4′-bpa)]
(<b>3a</b>) (4,4′-bpa = 1,2-bisÂ(4-pyridyl)Âethane and
4,4′-bpp = 1,3-bisÂ(4-pyridyl)Âpropane) 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 CoÂ(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 copperÂ(II) coordination polymers containing cyanoacetate
(cna) anion with various <i>N</i>,<i>N</i>′-ditopic
spacers [CuÂ(cna)<sub>2</sub>Â(pyz)]<sub><i>n</i></sub> (<b>1</b>), [CuÂ(cna)<sub>2</sub>Â(bpy)Â(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub> (<b>2</b>), [CuÂ(cna)<sub>2</sub>Â(dpe)]<sub><i>n</i></sub> (<b>3</b>),
[CuÂ(cna)<sub>2</sub>Â(dpe)]<sub><i>n</i></sub>Â(H<sub>2</sub>O)<sub><i>n</i></sub> (<b>4</b>), and [CuÂ(cna)<sub>2</sub>Â(bpa)]<sub><i>n</i></sub> (<b>5</b>)
(when pyz = pyrazine, bpy = 4,4′-bipyridyl, dpe = 1,2-diÂ(4-pyridyl)Âethylene,
and bpa = 1,2-diÂ(4-pyridyl)Âethane) were structurally and spectroscopically
characterized. Compound <b>1</b> shows a two-dimensional (2D)
sheet structure constructed from μ<sub>2</sub>-1,3Â(<i>syn,anti</i>) coordinative mode of cyanoacetate and μ<sub>2</sub>-pyz linking
adjacent CuÂ(II) centers. Compound <b>2</b> exhibits a one-dimensional
(1D) polymeric chain which is formed by μ<sub>2</sub>-bpy bridging
between [CuÂ(cna)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>] units,
whereas compounds <b>3</b>–<b>5</b> reveal 1D ladder-like
structures which are built from double-μ<sub>2</sub>-dpe/bpa
spacers connecting neighboring CuÂ(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
CoÂ(II) and NiÂ(II) ions. The magnetic properties of <b>1</b> and <b>3</b> exhibit very weak antiferromagnetic interactions between
CuÂ(II) centers