Ronghua Zeng

Synthesis, crystal structures and properties of Ln(III)–Cu(I)–Na(I) and Ln(III)–Ag(I) heterometallic coordination polymers

Nine 3D heterometallic coordination polymers, namely [NaLn2Cu6I5(IN)6(ox)(H2O)4]·H2O [Ln = La (1), Eu (2), Gd (3), Tb (4), HIN = isonicotinic acid, ox = oxalate], [Ln2Ag4(IN)5(ox)2(NO3)(H2O)2]·3H2O [Ln = Dy (5), (6) Ho], [LnAg(IN)2(ox)]·H2O [Ln = La (7), Pr (8), Tm (9)] have been successfully synthesized under hydrothermal conditions. Compounds 1–4 exhibit same unusual 3D pillared-layer heterometallic coordination frameworks that are built up by the Ln-ox-Na layers, 2D inorganic [(Cu6I5)+]n layers and IN ligands. Compounds 5 and 6 represent 3D coordination frameworks that are constructed from rare Ln(III)-ox-IN chains and Ag(I)-IN-ox layers. 3D coordination networks of compounds 7–9 are built up from 2D Ln(III)-IN-ox layers and Ag(I)-IN-ox subunits. Furthermore, the magnetic properties of compounds 5 and 6 and the luminescence properties of compounds 2, 4 and 5 have been investigated.

Facile synthesis of Li2C8H4O4–graphene composites as high-rate and sustainable anode materials for lithium ion batteries

Lithium terephthalate (Li2C8H4O4, PTAL), a carboxylate-based organic electrode material, displays high reversible capacity of up to 248 mA h g−1 and long cycle life, which is promoted by graphene as a sustainable anode material for lithium ion batteries.

Two new three-dimensional metal–organic frameworks with 4-connected diamondoid and unusual (6,16)-connected net topologies based on planar tetranuclear squares as secondary building units

Solvothermal reactions of Co2+ and Mn2+ salts with 2-(trifluoromethyl)-1H-4,5-imidazole dicarboxylic acid (H3TFMIDC) lead to two novel three-dimensional (3D) metal–organic frameworks (MOFs), namely, [Co6(μ3-TFMIDC)4(H2O)12]·15H2O (1) and [(Me2NH2)3][MnII6 MnIII(μ3-TFMIDC)6(H2O)6]·18H2O (2). Single-crystal X-ray diffraction analysis reveals that both of them are based on interesting planar tetranuclear squares [M4(TFMIDC)4] as secondary building units (SBUs). Compound 1 exhibits a unique 3D two-fold interpenetrated network with the diamondoid topology consisting of the tetranuclear square SBUs as 4-connected nodes, while compound 2 features an unusual (6,16)-connected 3D framework based on the novel tetranuclear square SBUs as 16-connected nodes and trivalent manganese ions as 6-connected nodes, representing the first 16-connected MOF utilizing planar tetranuclear square SBUs as building blocks. Our results open up new perspectives to design novel 3D extended MOFs, especially the unique highly connected 3D MOFs by employing planar tetranuclear square SBUs. Moreover, IR spectroscopy, powder X-ray diffraction, thermogravimetric analyses, and a study on the magnetic properties of both compounds, have been also performed.

Electrochemical behavior and simultaneous determination of catechol, resorcinol, and hydroquinone using thermally reduced carbon nano-fragment modified glassy carbon electrode

The electrochemical behaviors and simultaneous determination of three dihydroxybenzene isomers, i.e., catechol (CC), resorcinol (RC), and hydroquinone (HQ), are studied using a thermally reduced carbon nano-fragment modified glassy carbon electrode (CNF/GCE). The soluble CNF modifier with unique micro-/nano-structure and abundant edges and defective sites is prepared by chemically oxidizing graphite powders, ultrasonically crushing, and thermally reducing treatment in turn. It is shown that the oxidation peak currents of CC, RC, and HQ at the CNF/GCE are improved about 1.74, 2.88, and 1.05 times compared to that of the GCE. The diffusion process in bulk solution controls the electrochemical reaction of CC, RC, and HQ, and their reversible electrochemical process involves equal numbers of protons and electrons. Based on the enhanced electrocatalytic activity and enlarged separation of the anodic peak potential towards three dihydroxybenzene isomers at the CNF/GCE, the simultaneous differential pulse voltammetry (DPV) determination of CC, RC, and HQ, with detection limits (S/N = 3) of 5.0 × 10−7 mol L−1, 8.0 × 10−7 mol L−1 and 4.0 × 10−7 mol L−1, respectively, are obtained. The CNF/GCE also indicates high selectivity, stability, and reproducibility, and is comparable with results of high-performance liquid chromatography in real samples, clearly indicating its applicability.

The construction of two lanthanide coordination polymers based on 5-hydroxyisophthalate and bipyridine

Two lanthanide coordination polymers, [Tm2·(5-IPA)4·(2,2′-Hbipy)2]·3H2O (1, 5-H2IPA = 5-hydroxyisophthalic acid, 2,2′-bipy = 2,2′-bipyridine) and [Er·(5-HIPA)3·(4,4′-bipy)3·(H2O)2]·3H2O (2, 4,4′-bipy = 4,4′-bipyridine), have formed by hydrothermal synthesis. Complex 1 exhibits a 2-D coordination network containing parallelepiped-shaped voids occupied by guest 2′2-bipy molecules. Complex 2 possesses a 1-D linear chain structure. The 1-D chains are linked by 4,4′-bipy molecules to form a 3-D supramolecular framework. IR spectroscopy, elemental analysis, and thermogravimetric analysis were also investigated.

Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries.

The heteroaromatic organic compound, N,N’-diphenyl-1,4,5,8-naphthalenetetra- carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g−1 at the current density of 25 mA g−1. The capacity of 119 mAh g−1 can be retained after 100 cycles. Even at the high current density of 500 mA g−1, its capacity still reaches 105 mAh g−1, indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries.

C10H4O2S2/graphene composite as a cathode material for sodium-ion batteries

Organic electroactive materials are promising candidates for next generation sodium ion batteries (SIBs) due to their low cost, sustainability and environmental benignity. It is of great interest to develop organic compounds with multifunctional groups to be used as electrode materials for SIBs owing to their light weight, multi-electron reactions, redox stability and structural diversity. The organic compound 4,8-dihydrobenzo[1,2-b:4,5-b′] dithiophene-4,8-dione (BDT) was prepared by a facile solution method, and its graphene composite (BDT–G) was synthesized by a simple dispersion–deposition process. BDT–G as a cathode material demonstrated much enhanced electrochemical performance, including higher reversible capacity (217 mA h g−1vs. 145 mA h g−1), better cycling performance (∼175 mA h g−1vs. ∼100 mA h g−1 after 70 cycles at 0.2C), and higher rate capabilities (1.7 times better than BDT at 2C) compared with BDT. It is revealed that these improved electrochemical properties should be mainly attributed to the excellent electronic conductivity and ionic transport efficiency promoted by graphene. Furthermore, the fast electrode reaction of BDT with the help of unlimited electron transport via the two-dimensional graphene network results in enhanced usage of materials, and BDT in the composite with graphene could be inhibited from dissolution in the organic electrolyte.

A novel shuttle-like Fe3O4–Co3O4 self-assembling architecture with highly reversible lithium storage

We report the synthesis of a novel shuttle-like Fe3O4–Co3O4 self-assembling architecture through a facile hydrothermal method. The composite manifests quite excellent electrochemical performance as anodes of Li-ion batteries. It delivers a high reversible capacity of ∼1013 mA h g−1 at 100 mA g−1 after 100 cycles (∼1246 mA h g−1 at 0.5 A g−1, 864 mA h g−1 at 1 A g−1 and 625 mA h g−1 at 2 A g−1 after 50 cycles). The rate performance is also outstanding with a reversible capacity of 660 mA h g−1 even at 5 A g−1 and a capacity retention of 94% after 78 cycles. The synergetic effect of Co3O4 and Fe3O4, as well as the unique self-assembling architecture, may be responsible for the large enhanced electrochemical performance.