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A top-down method was developed to synthesize hierarchical composites consisting of NiCo2O4 nanocubes and graphene nanosheets through the electrostatic interaction of negatively charged graphene oxide nanosheets and positively charged NiCo2O4 spheres. Employed as anode materials for lithium-ion batteries, the hierarchical composites exhibit remarkably high electrochemical performance, including large reversible capacity, superior rate capability, and excellent cycling performance. Large reversible capacities of 1024 and 648 mA h g-1 are maintained at a current density of 500 and 3000 mA g-1, respectively, for over 200 cycles. The excellent electrochemical performance of the composite is attributed to the synergistic effect of the hierarchical structure, the well dispersed NiCo2O4 nanocubes and the uniform graphene coating. This work provides an effective and promising strategy for the rational structural design of the metal oxide electrode material.

Two-dimensional coordination polymers Zn2L2 (1) and Cd2L2·DMF·2H2O (2) (DMF = dimethylformamide) were synthesized under solvothermal conditions by the reactions between rigid dicarboxylate ligand containing two phosphine oxide groups, (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl (H2L), and the Zinc(II) and Cadmium(II) salts. The complexes were characterized by single-crystal X-ray diffraction, infrared spectra (IR), elemental analyses, thermogravimetric analyses (TGA), and photoluminescent studies. Complexes 1 and 2 are isomorphous, while 2 contains different guest molecules with one DMF and two waters. Luminescent properties investigation shows that complexes 1 and 2 have red-shifted 14 nm and 11 nm, respectively, and the luminescence efficiency is also different compared with the free ligand H2L.

A new ligand, 2,6-bis{3-(2-pyridyl)-1H-pyrazol-1-yl}pyridine (L1), was designed and synthesized. The reactions of the ligand with Zn(OAc)2·(H2O)2, and Cu(ClO4)2·(H2O)6 were carried out and a tetra-nuclear cluster [ZnII4L12(CH3COO)4(OH)2](ClO4)2 (1) and a dinuclear double helical complex [CuII2L12(H2O)2](ClO4)4 (2), were obtained and characterized by single crystal X-ray diffraction analyses. The solution behaviors of the complexes are also investigated.

A new bis-bidentate ligand, 1-[(5-methyl-2,2′-bipyridin-5′-yl)-methyl-1H-pyrazol-3-yl]-pyridine (L1), was designed and synthesized. The reactions of the ligand with [Cu(CH3CN)4]ClO4, Cu(ClO4)2·6H2O, AgNO3 and Cd(NO3)2·4H2O were carried out and dinuclear double helical complexes [CuI2L12][ClO4]2·CH3CN·0.5H2O (1), [CuII2L12(H2O)(CH3CN)][ClO4]4 (2), [AgI2L12](NO3)2·CH3CN (3) and [CdII2L12(NO3)4]·2H2O (4) were obtained and characterized by single crystal X-ray diffraction analyses, mass spectra, 1H NMR, and UV–Vis spectra. A dinuclear complex [NiII2L12(DMF)4](ClO4)4·H2O (5) was obtained by the reaction of the ligand with Ni(ClO4)2·6H2O. The results indicate that the formation of helicates is influenced by the structure of the bidentate ligand and the coordination geometry of the metal ions.

Using Schiff base as a phase transfer catalyst, ethoxycarbonyl isothiocyanate was synthesized by reacting ethyl chloroformate with sodium thiocyanate. In order to get the best synthetic technology, an orthogonal test (L 9(34)) was applied. The results show that reaction temperature, reaction time, content of catalyst and molar ratio of sodium thiocyanate to ethyl chloroformate are the main factors influencing the yield. The four factors chosen for the present investigation are based on the results of a single-factor test. The optimum synthetic technology is determined as follows: reaction temperature 35 °C, reaction time 3 h, the content of catalyst (molar fraction based on ethyl chloroformate) 1.5% and molar ratio of sodium thiocyanate to ethyl chloroformate 1.1. Under the optimized synthetic technology, the experimental yield reaches 96.8%.

Positive-ion mode electrospray mass spectrometry (ES-MS) was used to investigate the reaction of oligobipyridine ligand L (L = 5,5'-bis[2-(2,2'-bipyridin-6-yl)ethyl]-2,2'-bipyridine) with M(ClO4)2 in various mole ratios [M = Fe(II), Co(II), Ni(II) and Cu(II)]. The results indicate that the oligobipyridine L coordinated to the transitional metal ions to form mononuclear complexes. The ES mass spectra of isolated complex [FeL3](PF6)2 were measured under various electrospray conditions to examine the influence of the spray voltage, capillary temperature, capillary voltage, and tube lens offset on the fragmentation of the complex in electrospray ionization process. The results show that the fragmentation was mainly controlled by the capillary temperature, capillary voltage, and tube lens offset potential for Finnigan MAT LCQ system. The present study confirmed that the ES-MS is a powerful technique for determining the species existing in solution and for investigation of the reaction between oligobip...

A new asymmetric oligobipyridine ligand, 1- (5’-methyl-2, 2’-bipyridin-5-y1)-2- (6’-methyl-2, 2’-bipyridin-6-yl)ethane (L), in which the bipyridine units are bridged by CH2CH2 at 5,6’-position has been synthesized. The ligand L reacts with Cu(I) and Cu(I1) ions giving double-stranded helical complexes [Cu 2 1 L2](C104)2.Et20 (1) and [Cu 2 II L2,(OH)(H20) ] [ClO4]3(2), respectively. Complexes 1 and 2 were characterized by X-ray diffraction analyses, ES-MS, ESR and cyclic voltammetry, etc. Differing from the oligobipyridine ligands bridged by CH2CH2 at 6,6’-or 5,5’-position, the ligand L not only forms a double-stranded helicate with Cu(1) ion, but also gives a double-stranded helicate with Cu(I1) ion. The results show that the linkage mode of the spacer group to the bipyridine units exerts a great impact on the formation of helix.

A new monohelical OH − bridged dinuclear complex [Zn 2 (dmqpy)(OOCCH 3 ) 2 (μ-OH)][ClO 4 ] · 0.5EtOH, where dmqpy is 6,6⁗-dimethyl-2,2′:6′,2″:6″,2‴:6‴,2⁗-quinquepyridine, has been synthesized and characterized by X-ray crystallography: monoclinic, space group P 2 1 / c , a =13.670(1), b =14.751(1), c =16.782(1) A, β =96.59(1)°, U =3361.7(4) A 3 , Z =4, R =0.0601. Two Zn(II) ions are in different coordination modes, one is five-coordinate with a N 3 O 2 donor set and the other is N 2 O 2 four-coordinate with a distorted tetrahedral geometry, and the zinc ions are bridged by a hydroxyl group. The presence of the OH − bridge is further confirmed by electrospray mass and infrared spectroscopies. The solution properties of the complex were investigated by 1 H NMR spectroscopy. The results of NMR indicate that the complex has higher symmetry in solution than in the solid state.