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Five chiral metal-organic coordination compounds (CMOCCs), {[Cu4O(Lvcz)2Br4] ·H2O} n ( 1), {[Cd(HLvcz)2(NO3)2] ·0.25H2O} n ( 2), {[Cu2(HLvcz)2I2] ·H2O} n ( 3), {[Ag(HLvcz)2]CF3SO3} n ( 4), and {[Co2(HLvcz)(bdc)2(dmf)2] ·dmf ·3H2O} n ( 5; HLvcz = voriconazole, bdc = terephthalic acid), have been successfully prepared and structurally characterized. The chiral drug ligand voriconazole exhibits diverse modes of coordination in the five complexes, resulting in the formation of various architectures and properties. Complex 1 is a tetranuclear cluster, complex 2 exhibits a 1D double-strand chain structure in which hydrogen-bonding interactions lead to a 3D supramolecular network, complex 3 is a 1D chain structure with two different types of rings based on the rhombic dimer Cu2I2, complex 4 is a 2D structure with 63 topology that contains four types of C-H ···F hydrogen bonds, and complex 5 affords a 3D framework with sxa topology. Their properties, such as chirality, second-order nonlinear optical (NLO) effects, ferroelectric behavior and dielectric anomalies, have been investigated in the solid state. [ABSTRACT FROM AUTHOR]

Two trinuclear 3,5-diamio-1,2,4-triazole(Hdatz)-derived nickel(II) compounds, [Ni3(Hdatz)6(H2O)6]Br6 · 4H2O (1) and [Ni3(Hdatz)6(datz)2(H2O)4]Cl4 · 6H2O (2), are reported. Structural analyses reveal that in 1 the six Hdatz ligands are bidentate N1, N2-bridging coordination. However, the X-ray diffraction analysis shows that in 2 there are eight triazole ligands, six of which are neutral and two deprotonated. Four neutral triazoles are N1, N2-bridging and two monodentate; the deprotonated triazoles (datz) are bidentate N1, N2-bridging. The coexistence of both neutral and anionic triazole ligands as well as different coordination modes in one compound is relatively rare. The difference in coordination modes is believed to be anion-controlled. Both compounds are additionally characterized by elemental analysis, IR, and UV-Vis spectroscopy. [ABSTRACT FROM PUBLISHER]

Eight alkaline and alkaline-earth compounds derived from 2,4-dinitroimidazole (2,4-HDNI) were synthesized and characterized by elemental analysis, FT-IR, and TG-DSC, of which K(2,4-DNI) (1), Rb(2,4-DNI)(2,4-HDNI)(H2O)2 (2), and Ba(2,4-DNI)2(H2O)4 (3) were characterized by single-crystal X-ray diffraction analysis. All the three compounds were crystallized from water, but 1 was an anhydrate. The coordination number in 1 and 3 is 10, but in 2 is 9. The 2,4-DNI adopts either η3, η2, or η1 coordination modes depending on the metal cation. In 3, there is an inversion center located on the metal. Only in 2 does water play an important role for the construction of the structure; in 3 it is a hydrogen bonding participant. TG-DSC analyses of 1 were also performed, and non-isothermal decomposition reaction kinetics were obtained. [ABSTRACT FROM AUTHOR]

Six complexes, rubidium and cesium 3,5-dinitropyrid-2-onate (2DNPO), 3,5-dinitropyrid-4-onate (4NDPO), 3,5-dinitropyrid-4-one-N-hydroxylate (4DNPNO), were synthesized and characterized by elemental analysis, FT-IR, TG-DTG and X-ray single-crystal diffraction analysis. All the complexes crystallized from water and one of them was a hydrate. Rubidium 3,5-dinitropyrid-4-one-N-hydroxylate was crystallized with the 1 : 2 stoichiometry as Rb[H(4DNPNO)2] upon absorption of carbon dioxide. The structural determinations showed that the coordination sphere around a metal centre is made up of oxygen atoms and nitrogen atoms, except for the 4DNPNO complexes, where the coordination sphere accommodates exclusively oxygen atoms. The coordination numbers of the metal centers vary from 8, 10, 11 to 12, while the ligands, each employing its pyridone tautomer, link with metal cations. Bridging oxygen atoms play an important role in construction of two- and/or three-dimensional networks of these complexes. Hydrogen bonding contributes to the connectivity within a given sheet in Rb[H(4DNPNO)2]; aromatic π-π stacking interactions exist only in Cs(4DNPNO). The interactions between metal atoms and ligands are generally very weak. The organization of all layer structures appears to be governed mainly by steric effects and electrostatic forces with very little directional influence of the cations. The thermogravimetric analyses of these complexes showed the following consecutive processes: loss of NO2 groups, collapse of the pyridyl ring backbones and finally inorganic residue formation. These complexes could be used as probes in template effects of heavy alkali-metal cations in the organization of biorelevant ligands and as environment-friendly energetic catalysts in solid propellants. [ABSTRACT FROM AUTHOR]

Abstract: The as-cast and -annealed La–Mg–Ni-based A2B7-type La0.8− x Sm x Mg0.2Ni3.35Al0.1Si0.05 (x =0, 0.1, 0.2, 0.3, 0.4) electrode alloys were prepared, and the influences of the partial substitution of Sm for La on the structure and electrochemical performances of the alloys were investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical measurements. The results indicate that all the experimental alloys mainly consist of two phases, (La, Mg)2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure. The substitution of Sm for La gives rise to an obvious change in the electrochemical performances of the alloys. The discharge capacity of the as-cast and -annealed alloys first increases and then decreases with the growing of Sm content, whereas the cycle stability of the as-cast and -annealed alloys always increases with the rising of Sm content. Furthermore, the high rate discharge ability (HRD), the electrochemical impedance spectrum (EIS), Tafel polarization curves and potential-step measurements all indicate that the electrochemical kinetic properties of the alloy electrodes first increase then decrease with the rising amount of Sm substitution. [Copyright &y& Elsevier]

Abstract: The partial replacement of La by M (M = Pr, Zr) has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni-based A2B7-type electrode alloys. For this purpose, we adopt melt spinning technology to prepare the La0.75−x M x Mg0.25Ni3.2Co0.2Al0.1 (M = Pr, Zr; x = 0, 0.2) electrode alloys. Then systemically investigate the effects that the preparation methods and M (M = Pr, Zr) substitution have on the structures and electrochemical hydrogen storage characteristics of the alloys. The analysis of XRD and TEM reveals that the as-cast and spun alloys hold a multiphase structure, containing two main phases (La, Mg)2Ni7 and LaNi5 as well as a trace of residual phase LaNi2. Besides, the as-spun (M = Pr) alloy displays an entire crystalline structure, while an amorphous-like structure is detected in the as-spun (M = Zr) alloy, implying the replacement of La by Zr facilitates forming amorphous phase. Based upon electrochemical measurements, an impact engendered by melt spinning on the electrochemical performances of the alloys appears to be evident. The cycle stabilities monotonously augment with the growing of the spinning rate. The discharge capacity and high rate discharge ability (HRD), however, exhibit difference. For the (M = Pr) alloy, they first mount up and then fall with the rising of the spinning rate, whereas for the (M = Zr) alloy, they always decline as the spinning rate elevates. Furthermore, the replacement of La by M (M = Pr, Zr) considerably enhances the cycle stability of the alloys and the replacement of La by Pr clearly increases the discharge capacity, but the Zr replacement results in an adverse impact. [Copyright &y& Elsevier]