Synthesis, structure, magnetism and antibacterial properties of a 2-D nickel(II) metal–organic framework based on 3-nitrophthalic acid and 4,4′-bipyridine

<div><p>A 2-D nickel(II) mixed-ligand metal–organic framework [Ni(NPTA)(4,4′-bipy)(H₂O)]_n (<b>1</b>) was synthesized by reaction of 3-nitrophthalic acid (H₂NPTA) and 4,4′-bipyridine (4,4′-bipy) with Ni(II) under hydrothermal condition and characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. Compound <b>1</b> possesses a 2-D layer structure constructed from dinuclear nickel(II) building blocks in which two crystallographically equivalent Ni ions are bridged by two NPTA ligands. Furthermore, the layers are connected into 3-D supramolecular network by hydrogen bonds. The magnetism and antibacterial activity of <b>1</b> were investigated.</p></div

Controllable Fabrication of Zinc Borate Hierarchical Nanostructure on Brucite Surface for Enhanced Mechanical Properties and Flame Retardant Behaviors

A novel and efficient halogen-free composite flame retardant (CFR) consisting of a brucite core and a fine zinc borate [Zn₆O­(OH)­(BO₃)₃] hierarchical nanostructure shell was designed and synthesized via a facile nanoengineering route. It had been demonstrated that this unique hybrid structure possessed a high BET specific surface area (65 m²/g) and could significantly enhance the interfacial interaction when mixing with ethylene-vinyl acetate (EVA). This improved the transfer of stress between CFR particles and EVA matrix and increased the viscosity of EVA/EVA blends, which was beneficial for droplet inhibition and char forming. The mechanical properties and flammability behaviors of the EVA/CFR blends had been compared with the EVA/physical mixture (PM, with the given proportion of brucite and Zn₆O­(OH)­(BO₃)₃). The mechanical properties of EVA/CFR blends, especially the tensile strength (TS), presented a remarkable increase reaching at least a 20% increment. Meanwhile, with the same 45 wt % of fillers, the EVA/CFR formulation could achieve a limiting oxygen index (LOI) value of 33 (37.5 % higher than that of EVA/PM blends) and UL-94 V-0 rating. Moreover, the heat release rate (HRR), peak heat release rate (PHRR), total heat released (THR), smoke production rate (SPR) and mass loss rate (MLR) were considerably reduced, especially PHRR and SPR for EVA/CFR blends were reduced to 32%. According to this study, the design of fine structure might pave the way for the future development of halogen-free flame retardants combining both enhanced mechanical properties and excellent flame retardant behaviors

Two new fluorescent Zn²⁺ sensors exhibiting different sensing mode with subtle structural changes

<p>Two novel receptors <b>HL-1</b> and <b>HL-2</b> without and with hydroxyl groups were designed and synthesised. Both receptors showed highly selective coordination towards Zn²⁺ and exhibited diverse sensing behaviour due to the structural variations. <b>HL-1</b> showed monotonous ‘turn-on’ response towards Zn²⁺ while <b>HL-2</b> displayed highly Zn²⁺ sensitive ‘turn on’ and ‘ratiometric’ properties. Detailed Job plot experiment, single crystal data, ¹H NMR, ESI-MS, UV–vis and density functional theory calculation studies were conducted to understand the binding modes of <b>HL-1</b> and <b>HL-2</b> with Zn²⁺. These results revealed the binding stoichiometric ratio between receptors and Zn²⁺ were 1:1 with low detection limits and high binding constants.</p> <p>Two novel receptors <b>HL-1</b> and <b>HL-2</b> without and with hydroxyl groups were designed and synthesised via TCR reaction. Both of them showed selective coordination to Zn²⁺ ions but exhibited incongruent sensing mode due to structural variations. <b>HL-1</b> showed monotonous ‘turn-on’ whereas <b>HL-2</b> displayed highly sensitive ‘turn on’ and ‘ratiometric’ properties towards Zn²⁺.</p