Hydrothermal Synthesis and Structural Characterization of a New Hybrid Zinc Borate, [Zn(dap)2][B4O6(OH)2]

Exploration of the oxygen reduction reaction activity of four transition metal borates: synthesis, structure and characterization

Four new transition metal borates, [Co(1-MI)₂]·B₅O₇(OH)₃ (1, 1-MI = 1-methylimidazole), Co₂(PZ)₈(SO₄)₂·2H₃BO₃ (2, PZ = pyrazole), K₇{(BO₃)Co[B₁₂O₁₈(OH)₆]}·H₂O (3) and K₂{[Ni(PY)₂]₂·[(C₄H₂O₆)₂B]}₂ (4, PY = pyridine), have been successfully synthesized by a mild method. Their structures were determined by X-ray single crystal diffraction. These compounds were further characterized by FTIR, PXRD and UV-vis-NIR. It is worth noting that the catalytic properties of catalysts based on these four borates were explored, and that organically templated borate 1- and 2-based catalysts showed better ORR catalytic performance compared to 3- and 4-based catalysts. This may be caused by the supramolecular skeletons of 1 and 2 providing sufficient space and porosity.

A Way for Derived Carbon Materials by Thermal Etching Hybrid Borate for Electrochemical CO2 Reduction

Two hybridized skeleton borates [Zn(en)₂]·[B₇O₁₂(OH)] (1; en = ethylenediamine) and [Cd(1,3-dap)₂]·[B₅O₈(OH)]·H₂O (2; 1,3-dap = 1,3-diaminopropane) were solvothermally synthesized. The boron oxide clusters formed 2D planes, and these planes formed a 3D structure through co-oxygen links of metal complexes. Herein, a novel strategy has been developed, i.e., the derived guest carbon materials from semi-decomposed borate are incorporated into the void of host borate crystals in situ during the thermal etching process. Moreover, the effect of temperature on fluorescence of derived carbon materials was studied. By controlling the calcining temperature, carbon dots with obvious free radicals can be found via ESR technique. Carbon dots in the ethanol phase exhibited variable photoluminescence. Furthermore, it derived semi-decomposition carbon materials via thermal etching based on compounds 1 and 2. In an hydrogen cell reactor, carbon material Zn-based catalyst 1-200 catalyzes CO₂ reduction to CO with a selectivity that reaches 50.8% at -1.4 V vs RHE.

Hexaborate(2−) and Dodecaborate(6−) Anions as Ligands to Zinc(II) Centres: Self-Assembly and Single-Crystal XRD Characterization of [Zn{κ3O-B6O7(OH)6}(κ3N-dien)]·0.5H2O (dien = NH(CH2–CH2NH2)2), (NH4)2[Zn{κ2O-B6O7(OH)6}2 (H2O)2]·2H2O and (1,3-pnH2)3[(κ1N-H3N{CH2}3NH2) Zn{κ3O-B12O18(OH)6}]2·14H2O (1,3-pn = 1,3-diaminopropane)

Two zinc(II) hexaborate(2−) complexes, [Zn{κ3O-B6O7(OH)6}(κ3N-dien)]·0.5H2O (dien = NH(CH2CH2NH2)2) (1) and (NH4)2[Zn{κ2O-B6O7(OH)6}2(H2O)2]·2H2O (2), and a zinc(II) dodecaborate(6−) complex, (1,3-pnH2)3[(κ1N-H3N{CH2}3NH2)Zn{κ3O-B12O18(OH)6}]2·14H2O (1,3-pn = 1,3-diaminopropane) (3), have been synthesized and characterized by single-crystal XRD studies. The complexes crystallized through self-assembly processes, from aqueous solutions containing 10:1 ratios of B(OH)3 and appropriate Zn(II) amine complex: [Zn(dien)2](OH)2, [Zn(NH3)4](OH)2, and [Zn(pn)3](OH)2. The hexaborate(2−) anions in 1 and 2 are coordinated to octahedral Zn(II) centres as tridentate (1) or bidentate ligands (2) and the dodecaborate(6−) ligand in 3 is tridentate to a tetrahedral Zn(II) centre.

Two 1-D Coordination Polymers Containing Zinc(II) Hexaborates: [Zn(en){B6O7(OH)6}]·2H2O (en = 1,2-diaminoethane) and [Zn(pn){B6O7(OH)6}]·1.5H2O (pn = 1,2-diaminopropane)

The synthesis and characterization by single-crystal X-ray diffraction (XRD) studies of two new zinc(II) hexaborate(2−) complexes, [Zn(en){B6O7(OH)6}]·2H2O (en = 1,2-diaminoethane) (1) and [Zn(pn){B6O7(OH)6}]·1.5H2O (pn = 1,2-diaminopropane) (2), are reported. These complexes crystallize from aqueous solutions containing 10:1 ratios of B(OH)3 and the appropriate Zn(II) amine complexes ([Zn(en)3][OH]2 or [Zn(pn)3][OH]2) through self-assembly processes. The hexaborate(2−) anions in 1 and 2 are coordinated to two Zn(II) centers and form one-dimensional (1-D) polymeric coordination chains. R22(8) and R22(6) inter-chain H-bond interactions play an important role in these self-assembly processes and are discussed.

Transition-metal complexes with oxidoborates. Synthesis and XRD characterization of [(H3NCH2CH2NH2)Zn{κ3 O,O′,O′′-B12O18(OH)6-κ1 O′′′}Zn(en)(NH2CH2CH2NH3)]·8H2O (en=1,2-diaminoethane): a neutral bimetallic zwiterionic polyborate system containing the ‘isolated’ dodecaborate(6−) anion

The title compound, [(H3NCH2CH2NH2)Zn{κ3 O,O′,O′′-B12O18(OH)6-κ1 O′′′}Zn(en)(NH2CH2CH2NH3)]·8H2O (en=1,2-diaminoethane) (1), was prepared as a crystalline solid in moderate yield from the reaction of B(OH)3 with [Zn(en)3][OH]2 in aqueous solution (15:1) ratio. The structure contains a neutral bimetallic complex comprised of a unusual dodecaborate(6−) anion ligating two [H3NCH2CH2NH2Zn(en)n]3+ centers in a monodentate (n=1) or tridentate (n=0) manner.