Construction of ntt-Type Metal–Organic Framework from <i>C</i>₂‑Symmetry Hexacarboxylate Linker for Enhanced Methane Storage

By using a shortened hexacarboxylate linker of <i>C</i>₂-symmetry, a ntt-type metal–organic framework (UTSA-61) was constructed. Powder X-ray diffraction (XRD) crystallographic analysis revealed that UTSA-61 features the connection of the organic linker with four Cu₂ paddlewheels and one large -[Cu₂(O₂CR)₄-H₂O-Cu₂(O₂CR)₄]- cluster. This work confirms that a dendritic hexacarboxylate linker may support two cuboctahedral cages close to each other in ntt-type frameworks. Moreover, removing two ethynyl groups from PCN-61 (the prototypical ntt-type MOF) leads to optimized T-Td/T-Oh cages in UTSA-61 and results in preferable methane uptake than those of previously reported ntt-type MOFs. The activated UTSA-61a therefore exhibits a high methane storage capacity of 244 cm³ (STP) cm^–3 at 298 K and 65 bar, and a high working capacity of 176 cm³ (STP) cm^–3 (between 5 and 65 bar). These results rank UTSA-61a as one of the very few MOFs with both high volumetric methane storage and working capacities, rendering UTSA-61a as a promising adsorbent for on-board methane storage application

Solvent-Dependent Assemblies of Trinuclear Copper Cluster into Variable Frameworks Based on Mixed Ligands of Polyalcohol Amines and Organic Carboxylates

A systematic investigation on solvent-dependent assembly of trinuclear copper cluhster has resulted in eight related coordination polymers: Cu₃(teaH₂)₂(oba)₂(MeOH)₂ (<b>1</b>), Cu₃(teaH₂)₂(oba)₂(EtOH)₂ (<b>2</b>), Cu₃(teaH₂)₂(oba)₂·(<i>n</i>-PrOH) (<b>3</b>), Cu₃(teaH₂)₂(oba)₂ (<b>4</b>), Cu₃(teaH₂)₂(oba)₂(H₂O)₂ (<b>5</b>), Cu₃(MedeaH)₂(oba)₂(MeOH)₂ (<b>6</b>), Cu­[Cu₃(Medea)₂(oba)₂]·(solvent)_<i>x</i> (<b>7</b>), and [Cu₃(MedeaH)₂(oba)₂(H₂O)]·(<i>n</i>-PrOH)₂ (<b>8</b>) where oba = 4,4′-oxy-bis­(benzoate), teaH₃ = triethanolamine, and MedeaH₂ = <i>N</i>-methyldiethanolamine. In <b>1</b>–<b>8</b>, the trinuclear copper secondary building units (SBUs) (Cu₃) are furnished via the synergistic coordination of two organic ligands with metal centers. The structures of <b>1</b>–<b>8</b> exhibit two types of extensible modes (mode <b>I</b> for <b>1</b>, <b>2</b>, <b>3</b>, <b>7</b>, <b>8</b> and mode <b>II</b> for <b>4</b>, <b>5</b>, <b>6</b>) to Cu₃ SBUs. Mode <b>I</b> assembles Cu₃ SBUs into the one-dimensional (1D) iron-chain-like structure while mode <b>II</b> facilitates the two-dimensional (2D) undulate rectangular (4, 4) connection. Compounds <b>1</b> and <b>2</b> feature zero-dimensional (0D) molecular structures in which two strong hydrogen-bonding interactions extend its molecular components into 1D chains. Compound <b>3</b> comprises 1D chains interspersed by free solvent molecules, whereas compound <b>4</b> consists of 2D sheets excluding any solvent molecules. Compound <b>5</b> is also made up of 0D molecular structures but uses two classic hydrogen-bonding interactions to form its 2D supramolecular connection. Compound <b>6</b> has a 2D network similar to <b>4</b>. Compound <b>7</b> shows an unusual three-dimensional (3D) microporous framework in which a 1D chain is further assembled by extra Cu^II ions. Compound <b>8</b> provides 1D solvated structures with the voids occupied by lattice solvent molecules. The coordination ability of solvent molecules has been established for the underlying factor behind the different assemblies of compounds <b>1</b>–<b>8</b>. Compounds <b>5</b> and <b>8</b> from an alcohol/H₂O mixture indicate a behavior of selective coordination to the available coordination points of metal centers. The gas sorption property of compound <b>7</b> has also been investigated

Le fondement juridique du "tour d’échelle", note sous Cass. 3e civ., 15 février 2012

CommentaireNational audienc

Versatile Assembly of Metal-Coordinated Calix[4]resorcinarene Cavitands and Cages through Ancillary Linker Tuning

We propose a design strategy for assembly of metal-coordinated calix[4]­resorcinarene cavitands and cages by tuning of the ancillary linkers. Assembly of newly functionalized cavitand with angular isophthalic acid analogs affords three intriguing metal-coordinated cavitands with deep cavities, <b>1a</b>–<b>1c</b>. Further, by mediating appropriate spacers between two isophthalic acids, two bowl-shaped cavitands are successfully joined together to produce three elegant coordination cages with tunable sizes and shapes, <b>2a</b>–<b>2c</b>. The cavitand and cage crystals possess considerable amount of accessible porosities, as clearly established by gas adsorption measurements. Remarkably, <b>1a</b>–<b>1c</b> also exhibit high structural flexibilities, reversibly transforming between the open-pore and the narrow-pore structures, upon removal and sorption of guest molecules, as evidenced by diffraction and gas adsorption measurements. By combining experimental studies with density functional theory (DFT) calculations, we thoroughly elucidated the mechanism of the structural transformations in response to external stimuli in this new class of flexible porous solids

Versatile Assembly of Metal-Coordinated Calix[4]resorcinarene Cavitands and Cages through Ancillary Linker Tuning

We propose a design strategy for assembly of metal-coordinated calix[4]­resorcinarene cavitands and cages by tuning of the ancillary linkers. Assembly of newly functionalized cavitand with angular isophthalic acid analogs affords three intriguing metal-coordinated cavitands with deep cavities, <b>1a</b>–<b>1c</b>. Further, by mediating appropriate spacers between two isophthalic acids, two bowl-shaped cavitands are successfully joined together to produce three elegant coordination cages with tunable sizes and shapes, <b>2a</b>–<b>2c</b>. The cavitand and cage crystals possess considerable amount of accessible porosities, as clearly established by gas adsorption measurements. Remarkably, <b>1a</b>–<b>1c</b> also exhibit high structural flexibilities, reversibly transforming between the open-pore and the narrow-pore structures, upon removal and sorption of guest molecules, as evidenced by diffraction and gas adsorption measurements. By combining experimental studies with density functional theory (DFT) calculations, we thoroughly elucidated the mechanism of the structural transformations in response to external stimuli in this new class of flexible porous solids

Versatile Assembly of Metal-Coordinated Calix[4]resorcinarene Cavitands and Cages through Ancillary Linker Tuning

We propose a design strategy for assembly of metal-coordinated calix[4]­resorcinarene cavitands and cages by tuning of the ancillary linkers. Assembly of newly functionalized cavitand with angular isophthalic acid analogs affords three intriguing metal-coordinated cavitands with deep cavities, <b>1a</b>–<b>1c</b>. Further, by mediating appropriate spacers between two isophthalic acids, two bowl-shaped cavitands are successfully joined together to produce three elegant coordination cages with tunable sizes and shapes, <b>2a</b>–<b>2c</b>. The cavitand and cage crystals possess considerable amount of accessible porosities, as clearly established by gas adsorption measurements. Remarkably, <b>1a</b>–<b>1c</b> also exhibit high structural flexibilities, reversibly transforming between the open-pore and the narrow-pore structures, upon removal and sorption of guest molecules, as evidenced by diffraction and gas adsorption measurements. By combining experimental studies with density functional theory (DFT) calculations, we thoroughly elucidated the mechanism of the structural transformations in response to external stimuli in this new class of flexible porous solids

Versatile Assembly of Metal-Coordinated Calix[4]resorcinarene Cavitands and Cages through Ancillary Linker Tuning

We propose a design strategy for assembly of metal-coordinated calix[4]­resorcinarene cavitands and cages by tuning of the ancillary linkers. Assembly of newly functionalized cavitand with angular isophthalic acid analogs affords three intriguing metal-coordinated cavitands with deep cavities, <b>1a</b>–<b>1c</b>. Further, by mediating appropriate spacers between two isophthalic acids, two bowl-shaped cavitands are successfully joined together to produce three elegant coordination cages with tunable sizes and shapes, <b>2a</b>–<b>2c</b>. The cavitand and cage crystals possess considerable amount of accessible porosities, as clearly established by gas adsorption measurements. Remarkably, <b>1a</b>–<b>1c</b> also exhibit high structural flexibilities, reversibly transforming between the open-pore and the narrow-pore structures, upon removal and sorption of guest molecules, as evidenced by diffraction and gas adsorption measurements. By combining experimental studies with density functional theory (DFT) calculations, we thoroughly elucidated the mechanism of the structural transformations in response to external stimuli in this new class of flexible porous solids

Versatile Assembly of Metal-Coordinated Calix[4]resorcinarene Cavitands and Cages through Ancillary Linker Tuning

We propose a design strategy for assembly of metal-coordinated calix[4]­resorcinarene cavitands and cages by tuning of the ancillary linkers. Assembly of newly functionalized cavitand with angular isophthalic acid analogs affords three intriguing metal-coordinated cavitands with deep cavities, <b>1a</b>–<b>1c</b>. Further, by mediating appropriate spacers between two isophthalic acids, two bowl-shaped cavitands are successfully joined together to produce three elegant coordination cages with tunable sizes and shapes, <b>2a</b>–<b>2c</b>. The cavitand and cage crystals possess considerable amount of accessible porosities, as clearly established by gas adsorption measurements. Remarkably, <b>1a</b>–<b>1c</b> also exhibit high structural flexibilities, reversibly transforming between the open-pore and the narrow-pore structures, upon removal and sorption of guest molecules, as evidenced by diffraction and gas adsorption measurements. By combining experimental studies with density functional theory (DFT) calculations, we thoroughly elucidated the mechanism of the structural transformations in response to external stimuli in this new class of flexible porous solids

Protective Effect of Sevoflurane Postconditioning against Cardiac Ischemia/Reperfusion Injury via Ameliorating Mitochondrial Impairment, Oxidative Stress and Rescuing Autophagic Clearance

<div><p>Background and Purpose</p><p>Myocardial infarction leads to heart failure. Autophagy is excessively activated in myocardial ischemia/reperfusion (I/R) in rats. The aim of this study is to investigate whether the protection of sevoflurane postconditioning (SPC) in myocardial I/R is through restored impaired autophagic flux.</p><p>Methods</p><p>Except for the sham control (SHAM) group, each rat underwent 30 min occlusion of the left anterior descending coronary (LAD) followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC) staining. Cardiac function was examined by hemodynamics and echocardiography. The activation of autophagy was evaluated by autophagosome accumulation, LC3 conversion and p62 degradation. Potential molecular mechanisms were investigated by immunoblotting, real-time PCR and immunofluorescence staining.</p><p>Results</p><p>SPC improved the hemodynamic parameters, cardiac dysfunction, histopathological and ultrastructural damages, and decreased myocardial infarction size after myocardial I/R injury (<i>P</i> < 0.05 vs. I/R group). Compared with the cases in I/R group, myocardial ATP and NAD⁺ content, mitochondrial function related genes and proteins, and the expressions of SOD2 and HO-1 were increased, while the expressions of ROS and Vimentin were decreased in the SPC group (<i>P</i> < 0.05 vs. I/R group). SPC significantly activated Akt/mTOR signaling, and inhibited the formation of Vps34/Beclin1 complex via increasing expression of Bcl2 protein (<i>P</i> < 0.05 vs. I/R group). SPC suppressed elevated expressions of LC3 II/I ratio, Beclin1, Atg5 and Atg7 in I/R rat, which indicated that SPC inhibited over-activation of autophagy, and promoted autophagosome clearance. Meanwhile, SPC significantly suppressed the decline of Opa1 and increases of Drp1 and Parkin induced by I/R injury (<i>P</i> < 0.05 vs. I/R group). Moreover, SPC maintained the contents of ATP by reducing impaired mitochondria.</p><p>Conclusion</p><p>SPC protects rat hearts against I/R injury via ameliorating mitochondrial impairment, oxidative stress and rescuing autophagic clearance.</p></div

SPC narrows the I/R-induced accumulation of protein aggregates.

<p><b>(A)</b> Cardiac tissues at papillary muscles level were collected and the cryosectioning was prepared. The immunohistochemical analysis of protein aggregates stained with anti-Vimentin is shown. Hoechst 33342 was used to stain cell nuclei. The immunofluorescence was examined by a confocal microscope. Scale bar: 20μm. <i>n</i> = 3 /group <b>(B)</b> Representative immunoblots of nuclear protein from all groups detected with a Vimentin-specific antibody. H3 was utilized to normalize the amount of protein. <i>n</i> = 4 /group. The columns and errors bars represent means ± SD. * <i>P</i> < 0.05 vs. SHAM group; # <i>P</i> < 0.05 vs. I/R group.</p