Molecular Tectonics of Four-Connected Network Topologies by Regulating the Ratios of Tetrahedral and Square-Planar Building Units

Assembly of the 4-connected building units leads to three three-dimensional frameworks, {[Cd­(TPPBDA)­(OH)₂]·2H₂O·4DMA}_<i>n</i> (<b>1</b>), {[Cd­(TPPBDA)_1/2(tpdc)]·DMF}_<i>n</i> (<b>2</b>), and {[Zn­(TPPBDA)_1/2(bpdc)]·3H₂O·3DMF}_<i>n</i> (<b>3</b>) (TPPDBA = <i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetrakis­(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine, H₂tpdc = 4,4″-dicarboxyl-(1,1′,3′,1″)-terphenyl), H₂bpdc = biphenyldicarboxylic acid, DMF = <i>N</i>,<i>N</i>-dimethylformamide, DMA = <i>N</i>,<i>N</i>-dimethylacteamide), which are based on different ratios of tetrahedral (T) and square-planar (S) building units. For compound <b>1</b>, T and S nodes are in the ratio of 1:1, which is the feature of pts. While T/S is 2:1 in compound <b>2</b> to form a bbf framework, for compound <b>3</b>, the TPPBDA ligand and the metal center are both in tetrahedral configuration, which constructs a dia net with the ratio of 2:0 (T/S). In addition, the compound <b>2</b> exhibits high selectivity for CO₂ over CH₄, showing a hysteretic sorption–desorption loop

Three Highly Stable Cobalt MOFs Based on “Y”-Shaped Carboxylic Acid: Synthesis and Absorption of Anionic Dyes

Three Co­(II) metal–organic frameworks (MOFs) were synthesized employing a rational design approach. On the basis of the different structures of three complexes, we tested their absorption properties toward two anionic dyes. The absorption results indicate that not only uncoordinated functional groups in the structure play an important role in adsorbing capacity but also physical forces can affect absorbing ability. Water stability testing shows that three crystals display high stability in aqueous solutions with different pH values. To our delight, the framework integrity of three complexes can be well-retained even after absorbing dyes

Facile Synthesis of Ni(OH)₂/Carbon Nanofiber Composites for Improving NiZn Battery Cycling Life

Carbon nanofibers (CNFs) were successfully functionalized by the hydrothermal treatment of wet CNFs containing concentrated HNO₃. The method of synthesis was facile and eco-friendly. With the use of oxidized CNFs as substance, Ni­(OH)₂/oxidized CNFs hybrid materials were prepared by taking a two-step solution phase reaction. The XRD pattern and TEM image suggested a well crystalline Ni­(OH)₂ nanoplate with β-phase structure growth on the surface of CNFs. Electrochemistry test results displayed high specific capacitances and long cycle life of the composites. With the use of Ni­(OH)₂/CNFs as cathode and Zn foil as anode, assembled NiZn pouch cells could achieve ∼1.75 V discharge voltage plateau, with a specific capacity ranging from 184 mAh·g^–1 at a discharging current density of 5 mA·cm^–2 to 91 mAh·g^–1 at a discharging current density of 50 mA·cm^–2. Its cycle stability was up to 1200 cycles with a capacity retention of >96% at attaining an energy density of 150 Wh·kg^–1. Compared with a 6 mol·L^–1 KOH solution electrolyte battery, the sodium polyacrylate gel electrolyte battery displayed better cycle performance. The function of the gel electrolyte was discussed. The facile method could be extended to the oxidization of the other carbon materials and synthesis of the others carbon composites