Search NASA⌕ Search

SEARCH · Search NASA

Results for “MONOCRYSTALS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Supramolecular hybrids of polytungstates and their adsorption properties for methylene blue

Two supramolecular hybrids [Ni(mbpy){sub 3}]{sub 2}[V{sub 2}W{sub 4}O{sub 19}]·6H{sub 2}O (1) and [Ni(mbpy){sub 3}]{sub 2}[VW{sub 12}O{sub 40}] (2) (mbpy=4,4′-dimethyl-2,2′-bipyridyl) had been synthesized and characterized. Single crystal X-ray diffraction analyses revealed that the anionic moieties in two hybrids belong to typical Lindqvist and α-Keggin-type structures, respectively. The counter ion [Ni(mbpy){sub 3}]{sup 2+} units were anchored to the polyanions via non-covalent intermolecular interactions. These supramolecular hybrids exhibit reversible adsorption–desorption performance for organic dye methylene blue (MB). Hybrid 2 shows a fast adsorption behavior towards MB and a relatively high value can be reached within 5 min in dark. Both 1 and 2 are structurally stable and can be easily separated from the reaction system for reuse. - Graphical abstract: Supramolecular hybrids of polytungstates have been synthesized and characterized, which exhibit the reversible adsorption–desorption performance for organic dye methylene blue.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3}: A case study in flux growth of lanthanide-rich intermetallics

The intermetallic Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3} (x≈0.65) was prepared from reaction of germanium and carbon in Nd/Co eutectic flux in an alumina crucible. This phase exhibits a new structure type in orthorhombic space group Pbcm, with unit cell parameters a=8.001(1) Å, b=11.696(2) Å, c=15.020(3) Å (Z=4; R{sub 1}=0.0234). The structure features germanium-centered neodymium clusters Ge@Nd{sub 9} which share faces to form layers separated by zigzag chains of cobalt atoms capped by carbon. Density of states calculations confirm that this compound is metallic, and indicate that the cobalt should not have a magnetic moment. This is supported by magnetic susceptibility measurements which show a low temperature ferromagnetic ordering at T{sub C}=50 K due to the Nd{sup 3+} ions. Magnetization field dependence studies on single crystals indicate this compound is a strong ferromagnet with large anisotropy; the Nd{sup 3+} magnetic moments align along the a-axis. - Graphical abstract: Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3} (x≈0.65) contains germanium-centered neodymium clusters Ge@Nd{sub 9} which share faces to form layers separated by zigzag chains of cobalt atoms capped by carbon. - Highlights: • Nd{sub 8}Ge{sub 2}Co{sub 3.35}Al{sub 0.65}C{sub 3} grows as large crystals from reactions in Nd/Co eutectic flux. • Structure features Ge@Nd{sub 9} clusters and zigzag cobalt chains capped by carbon. • Cobalt has no magnetic moment; Nd{sup 3+} ion moments order ferromagnetically. • Hard ferromagnet with strong anisotropy below T{sub C} of 50 K. • Flux growth and structural trends of lanthanide-rich intermetallics are reviewed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Two new Cu{sup I} compounds with zwitterionic tetrazolate ligand: In situ synthesis, crystal structures, luminescence and photocatalytic properties

Two 2D new Cu(I) coordination polymers, namely [Cu{sub 2}(mpTZ){sub 2}Br{sub 2}]·H{sub 2}O (1), and [Cu{sub 2}(mpTZ){sub 2}N{sub 3}]ClO{sub 4} (2) (mpTZ=N-methyl-4-pyridinium tetrazolate) have been synthesized under solvothermal conditions, in which the mpTZ ligands and Cu{sup I} ions were obtained through in situ [2+3] cycloaddition reaction and reduction reaction of Cu{sup II} salts, respectively. Both compounds have been structural characterized by single crystal X-ray diffraction, FT-IR, PXRD and EA. Compound 1 exhibits a 2D neutral coordination network, in which the Cu{sup I} ions are bridged by η{sub 3}−1, 2, 4-tetrazolate into 2D sheet. In compound 2, the Cu{sup I} ions are linked by azide (in µ{sub 3}−1, 1, 3 bridging mode) and tetrazolate (in η{sub 3}−1, 2, 3 bridging mode) anions into 2D positively charged sheet, extended along the bc plane. Both compounds 1 and 2 exhibit intense bluish green luminescence in the solid state. Photocatalytic performances of the two compounds for the degradation of methylene blue (MB) under visible light were also investigated and the MB degradation in the presence of 1 was nearly complete (99%) after 150 min. - Graphical abstract: Two Cu{sup I}CPs have been solvothermally synthesized through the in situ [2+3] cycloaddition and metal reduction reaction. Both compounds exhibit intense luminescence and high photocatalytic degradation under visible light. - Highlights: • Two new Cu{sup I}-based CPs are solvothermally synthesized through in situ [2+3] cycloaddition reaction and metal reduction reaction. • Both compounds exhibit strong luminescence and photocatalytic degradation of methylene blue (MB) under visible light. • The MB degradation in the presence of 1 is nearly complete (99%) after 150 min.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Quaternary rare-earth arsenides REAg{sub 1−x}Zn{sub y}As{sub 2} (RE=La–Nd, Sm, Gd–Dy) with tetragonal SrZnBi{sub 2}- and HfCuSi{sub 2}-type structures

Reactions of the elements at 800 °C with the nominal compositions REAg{sub 1−x}Zn{sub x}As{sub 2} resulted in quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2} in which the combined Ag and Zn content deviates increasingly from unity in the Zn-richer phases, reflecting the transition from the fully stoichiometric ternary silver-containing arsenides REAgAs{sub 2} to the substoichiometric zinc-containing ones REZn{sub 0.67}As{sub 2}. Powder X-ray diffraction analysis indicated SrZnBi{sub 2}-type (space group I4/mmm, Z=4; RE=La, Ce) and HfCuSi{sub 2}-type structures (space group P4/nmm, Z=2; RE=Pr, Nd, Sm, Gd, Tb, Dy). Single-crystal X-ray diffraction analysis performed on LaAg{sub 0.5}Zn{sub 0.5}As{sub 2}, PrAg{sub 0.5}Zn{sub 0.5}As{sub 2}, and NdAg{sub 0.5}Zn{sub 0.5}As{sub 2} indicated that the Ag and Zn atoms are disordered within metal-centred tetrahedra and provided no evidence for distortion of the square As nets. The small electron excess tolerated in these quaternary arsenides and the absence of distortion in the square nets can be traced to the occurrence of As–As states that are only weakly antibonding near the Fermi level. PrAg{sub 0.5}Zn{sub 0.5}As{sub 2} and NdAg{sub 0.5}Zn{sub 0.5}As{sub 2} are paramagnetic with effective magnetic moments consistent with trivalent RE species. - Graphical abstract: On proceeding from fully stoichiometric REAgAs{sub 2} to substoichiometric REZn{sub 0.67}As{sub 2}, deficiencies in Zn content become increasingly prominent in quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2}. - Highlights: • Ag and Zn atoms are disordered within quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2}. • In Zn-richer phases, Zn deficiencies develop to counteract electron excess. • Distortions of square As net appear to be suppressed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Solvent induced synthesis, structure and properties of coordination polymers based on 5-hydroxyisophthalic acid as linker and 1,10-phenanthroline as auxiliary ligand

Three new coordination polymers [Mn(hip)(phen) (H{sub 2}O)]{sub n} (1), [Co(hip)(phen) (H{sub 2}O)]{sub n} (2), and [Cd(hip) (phen) (H{sub 2}O)]{sub n} (3) (H{sub 2}hip=5-hydroxyisophthalic acid; phen=1,10-phenanthroline) have been synthesized by solvo-hydrothermal method using diethyl formamide-water (DEF-H{sub 2}O) as solvent system. Single-crystal X-ray diffraction analysis reveals that all three coordination polymers 1, 2 and 3 crystallize in monoclinic space group P2/n. Metal ions are inter-connected by hydroxyisophthalate anions forming zig-zag 1D chain. 1D chains are further inter-connected by hydrogen bonding and π–π stacking interactions leading to 3D supramolecular architecture. Hydrogen-bonding and π–π stacking provide thermal stability to polymers. Compounds 1 and 2 are paramagnetic at room temperature and variable temperature magnetic moment measurements revealed weak ferromagnetic interactions between metal ions at low temperature. Compound 3 exhibits excellent photoluminescence with large Stokes shift. - Graphical abstract: 1D helical chains of coordination polymers were synthesized by solvo-hydrothermal reaction of 5-hydroxyisopthalic acid and 1,10-phenanthroline with MnCl{sub 2}·4H{sub 2}O / CoCl{sub 2}·6H{sub 2}O / Cd(NO{sub 3}){sub 2}·6H{sub 2}O. - Highlights: • Solvent induced synthesis of three coordination polymers with 1D zig-zag structure. • Crystal structures of coordination polymers are reported and discussed. • 1,10-Phenanthroline influences magnetic and luminescent properties of polymers. • Coordination polymer of Cd is luminescent exhibiting large Stokes shift.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Synthesis, crystal structure and photoluminescence property of Eu/Tb MOFs with mixed polycarboxylate ligands

Lanthanide MOFs, [Eu(TCA)(NDC)·H{sub 2}O]{sub n} (1) and [Tb(TCA)(NDC)·H{sub 2}O]{sub n} (2), have been prepared with the mixed aromatic carboxylate ligands, namely, 4,4′,4″-tricarboxytriphenylamine (H{sub 3}TCA) and 1,4-naphthalenedicarboxylate (H{sub 2}NDC). Single-crystal X-ray diffraction analysis reveals that isomorphic 1 and 2 present pillar-layered 3D framework that Eu/Tb(III) bond with carboxylate in various coordination fashions. Optical investigation indicates that the as-prepared compounds feature characteristic luminescence emission bands of Eu/Tb ions in the visible regions at room temperature. Moreover, compound 2 shows a relatively longer luminescence lifetime (τ=0.342 ms) and significantly enhanced quantum yield (Φ{sub overall}=11%) comparing with those of 1 (τ=0.335 ms, Φ{sub overall}=0.06%). - Graphical abstract: Synoptic: Two Ln-MOFs (Ln=Eu{sup III}, Tb{sup III}) with mixed polycarboxylate ligands present different luminescent properties. - Highlights: • Two Eu/Tb-MOFs with H{sub 3}TCA and H{sub 2}NDC ligands have been obtained. • The ancillary ligand is employed to decrease water molecule coordinate numbers. • 2displays superior quantum yield and lifetime than those of 1.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Copper(II) perrhenate Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}: Synthesis from isopropanol and CuReO{sub 4}, structure and properties

The crystal structure of Cu{sup +}Re{sup 7+}O{sub 4} is capable of a quasi-reversible incorporation of C{sub 3}H{sub 7}OH molecules. A room-temperature reaction between CuReO{sub 4} and C{sub 3}H{sub 7}OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu{sup 2+}(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}. Upon heating under reducing conditions, this compound transforms back into CuReO{sub 4}, albeit with ReO{sub 2} and metallic Cu as by-products. The crystal structure of Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} solved from single-crystal X-ray diffraction (Pbca, a=10.005(3) Å, b=7.833(2) Å, and c=19.180(5) Å) reveals layers of corner-sharing CuO{sub 6}-octahedra and ReO{sub 4}-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} is paramagnetic down to 4 K because the spatial arrangement of the Cu{sup 2+} half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μ{sub B} is slightly above the spin-only value and typical for Cu{sup 2+} ions. - Highlights: • Novel Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} compound has a sequence of inorganic and organic layers. • Hydrogen bonds provide an additional bonding Isopropanol molecules serve as a reducing agent during decomposition. • No direct Cu-O-Re-O-Cu connections via d{sub x2-y2} orbital of Cu{sup 2+} explain paramagnetism. • Hydrogen bonds provide an additional bonding. • Isopropanol molecules serve as a reducing agent during decomposition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16}, the new tellurite halides of the tetragonal Rb{sub 6}LiNd{sub 11}[SeO{sub 3}]{sub 12}Cl{sub 16} structure type

Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} (I) and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16} (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn{sub 11}(TeO{sub 3}){sub 12}] and [M{sub 6}X{sub 16}] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. - Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Top-seeded solution crystal growth of noncentrosymmetric and polar Zn{sub 2}TeMoO{sub 7} (ZTM)

A top-seeded solution growth (TSSG) method was used to grow large, centimeter size, crystals of Zn{sub 2}TeMoO{sub 7} (ZTM) – a noncentrosymmetric and polar material. A TeO{sub 2}–MoO{sub 3} mixture in combination with the parent compound was used as a flux. The morphologies of the crystals can be controlled by different rotation speeds. Optical spectra indicate that ZTM is transparent up to 5.25 µm with a UV absorption edge of 300 nm. In addition, the refractive index along the optical x, y, and z axes was measured at different wavelengths. - Highlights: • Zn{sub 2}TeMo{sub 2}O{sub 7} crystals were grown by top-seeded solution growth (TSSG) method. • The morphology of the single crystals is controllable by changing rotation speed. • Optical transmission spectra indicate Zn{sub 2}TeMo{sub 2}O{sub 7} has a broad transmission range. • Refractive index along optical axes was measured at different wavelengths.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Metal–organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L){sub 2}]{sub n} (1) and [Co{sub 3}(L){sub 4}(N{sub 3}){sub 2}·2MeOH]{sub n} (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 8}.10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co{sub 3}] units. And the magnetic properties of 1 and 2 have been studied. - Graphical abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with tetrazole heterocycle ligands bearing acetate groups are reported. - Highlights: • Two novel Cobalt(II) complexes with tetrazole acetate ligands were synthesized. • The magnetic properties of two complexes were studied. • Azide as co-ligand resulted in different structures and magnetic properties. • The new coordination mode of tetrazole acetate ligand was obtained.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Single crystal magnetic structure and susceptibility of CoSe{sub 2}O{sub 5}

The structure of CoSe{sub 2}O{sub 5} consists of one-dimensional ribbons of edge-sharing CoO{sub 6} octahedra bound together by polyanionic subunits of Se{sub 2}O{sub 5}. Previous work on polycrystalline samples reported a canted antiferromagnetic arrangement of the magnetic moments below the ordering temperature of 8.5 K. Here, we report a single crystal investigation using variable temperature and field magnetic susceptibility and low-temperature neutron diffraction to more precisely characterize the nature of the magnetic ground state of CoSe{sub 2}O{sub 5}. Contrary to previous reports, we find that the single crystal magnetic structure shows no canting of the antiferromagnetic ground state, and in the process have identified several field-induced changes to the magnetization. We discuss these results in the context of the revised magnetic structure and highlight the importance of crystal growth for the accurate characterization of these properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Structure and optical properties of [In{sub 1−2x}Sn{sub x}Zn{sub x}]GaO{sub 3}(ZnO){sub m}

Compounds of [In{sub 1−2x}Sn{sub x}Zn{sub x}]GaO{sub 3}(ZnO){sub 1} (x≤0.22) and [In{sub 1−2x}Sn{sub x}Zn{sub x}]GaO{sub 3}(ZnO){sub 2} (x≤0.42) were prepared by solid state processing proving a substantial solid solution of Sn in the layered compounds InGaO{sub 3}(ZnO){sub m} (m=1, 2). Single crystal X-ray diffraction of the compounds reveals two In{sup 3+} ions to be substituted by one Sn{sup 4+} and one Zn{sup 2+} at the octahedral layer preserving the average charge of +3 at these sites. The substitution does not lead to an ordering of the ions but proves for the first time that the octahedral site can be occupied by different ions while all characteristics of the layered structures remain unchanged. Consequences of indium substitution are (i) decrease of the a axis compared to InGaO{sub 3}(ZnO){sub m} according to smaller ionic radii of Sn{sup 4+} and Zn{sup 2+} compared to In{sup 3+} and (ii) shift of the optical band gap to higher energies shown by UV–vis measurements. - Graphical abstract: Substitution limits of indium in InGaO{sub 3}(ZnO){sub m} (IGZO) by Sn and Zn are studied for m=1, 2 by single crystal X-ray diffraction and micro-chemical analysis. - Highlights: • New Oxides [In{sub 1−2x}Sn{sub x}Zn{sub x}]GaO{sub 3}(ZnO){sub m} (m=1, 2) with IGZO type structure. • Sn and Zn substitute for In at octahedral sites. • Crystal structures were characterized by single crystal X-ray diffraction. • Optical band gap energies were determined by UV–vis spectroscopy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Self-assembly of [UO{sub 2}X{sub 4}]{sup 2−} (X=Cl, Br) dianions with γ substituted pyridinium cations: Structural systematics and fluorescence properties

Room temperature self-assembly of [UO{sub 2}X{sub 4}]{sup 2−} (X=Cl, Br) with γ substituted pyridinium cations has resulted in the formation of twelve compounds that were studied via single crystal X-ray diffraction and fluorescence spectroscopy. Systematic variation of electron donating groups on the pyridinium species is shown to influence the presence and/or strength of various supramolecular synthons, including hydrogen bonding and pi interactions. Combinations of such non-covalent interactions (NCIs) have given rise to a range of supramolecular assemblies, and are shown to influence uranyl emission by way of second sphere coordination to equatorial ligands. - Graphical abstract: Supramolecular assembly of the [UO{sub 2}Cl{sub 4}]{sup 2−} dianion with pyridinium cations is a viable synthetic route to the growth of uranyl containing single crystals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Conformational diversity of flexible ligand in metal-organic frameworks controlled by size-matching mixed ligands

Hydrothermal reactions of N-auxiliary flexible exo-bidentate ligand 1,3-bis(4-pyridyl)propane (bpp) and carboxylates ligands naphthalene-2,6-dicarboxylic acid (2,6-H{sub 2}ndc) or 4,4′-(hydroxymethylene)dibenzoic acid (H{sub 2}hmdb), in the presence of cadmium(II) salts have given rise to two novel metal-organic frameworks based on flexible ligands (FL-MOFs), namely, [Cd{sub 2}(2,6-ndc){sub 2}(bpp)(DMF)]·2DMF (1) and [Cd{sub 3}(hmdb){sub 3}(bpp)]·2DMF·2EtOH (2) (DMF=N,N-Dimethylformamide). Single-crystal X-ray diffraction analyses revealed that compound 1 exhibits a three-dimensional self-penetrating 6-connected framework based on dinuclear cluster second building unit. Compound 2 displays an infinite three-dimensional ‘Lucky Clover’ shape (2,10)-connected network based on the trinuclear cluster and V-shaped organic linkers. The flexible bpp ligand displays different conformations in 1 and 2, which are successfully controlled by size-matching mixed ligands during the self-assembly process. - Graphical abstract: Compound 1 exhibits a 3D self-penetrating 6-connected framework based on dinuclear cluster, and 2 displays an infinite 3D ‘Lucky Clover’ shape (2,10)-connected network based on the trinuclear cluster. The flexible 1,3-bis(4-pyridyl)propane ligand displays different conformations in 1 and 2, which successfully controlled by size-matching mixed ligands during the self-assembly process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Synthesis, crystal growth, structural and magnetic characterization of NH{sub 4}MCl{sub 2}(HCOO), M=(Fe, Co, Ni)

An ambient-pressure solution route and an improved solvothermal synthetic method have been developed to produce polycrystalline powders and large single crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni). The magnetic structure of the 1D linear chain compound NH{sub 4}FeCl{sub 2}(HCOO) has been determined by low-temperature neutron powder diffraction, revealing ferromagnetic intra-chain interactions and antiferromagnetic inter-chain interactions. The newly-reported Co and Ni analogs are isostructural with NH{sub 4}FeCl{sub 2}(HCOO), but there are significant differences in the magnetic properties of each compound; the Ni analog behaves similarly to the Fe compound but with stronger magnetic coupling, exhibiting antiferromagnetic ordering (T{sub N}=8.5 K) and a broad metamagnetic transition between 2 and 5 T, while the Co analog does not order magnetically above 2 K, despite strong antiferromagnetic nearest-neighbor interactions. - Graphical abstract: Large single crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni), which adopt a 1D zig-zag chain structure, can be grown via a solvothermal method. Neutron diffraction experiments revealed that the magnetic structure of the iron compound exhibits ferromagnetic intra-chain coupling and antiferromagnetic inter-chain coupling. - Highlights: • Large crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni) have been grown solvothermally. • The magnetic structure of M=Fe was solved by low-temperature neutron diffraction. • NH{sub 4}FeCl{sub 2}(HCOO) exhibits FM intra-chain and AFM inter-chain interactions. • NH{sub 4}CoCl{sub 2}(HCOO) exhibits no 3D magnetic ordering above 2 K. • NH{sub 4}NiCl{sub 2}(HCOO) exhibits AFM ordering (T{sub N}=8.5 K) and FM intra-chain interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Carboxylate ligands induced structural diversity of zinc(II) coordination polymers based on 3,6-bis(imidazol-1-yl)carbazole: Syntheses, structures and photocatalytic properties

Solvothermal reactions of Zn(NO{sub 3}){sub 2}·6H{sub 2}O with 3,6-bis(1-imidazolyl)carbazole (3,6-bmcz) and 1,4-benzenedicarboxylic acid (1,4-H{sub 2}bdc), p-phenylenediacetic acid (p-H{sub 2}pda), benzophenone-4,4-dicarboxylic acid (H{sub 2}bpda) afforded three coordination polymers [Zn(1,4-bdc)(3,6-bmcz)]{sub n} (1), {[Zn(p-pda)(3,6-bmcz)]·1.5H_2O}{sub n} (2) and {[Zn(bpda)(3,6-bmcz)]·0.25H_2O}{sub n} (3). Complexes 1–3 were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. Complex 1 shows 3D structure with 2D nets inclined polycatenation. Complexes 2 and 3 possess an extended 3D supramolecular architecture based on their respective 2D layers through hydrogen-bonding interactions and the π···π stacking interactions. The solid state luminescent and optical properties of 1–3 at ambient temperature were also investigated. A comparative study on their photocatalytic activity toward the degradation of methylene blue in polluted water was explored. - Graphical abstract: Reactions of Zn(NO{sub 3}){sub 2} and 3,6-(1-imidazolyl)carbazole with 1,4-benzenedicarboxylic acid, p-phenylenediacetic acid or benzophenone-4,4-dicarboxylic acid afforded three coordination polymers with different topologies and photocatalytic activity. - Highlights: • Reactions of 1,4-H{sub 2}bdc, p-H{sub 2}pda or H{sub 2}bpda with 3,6-bmcz and Zn(II) gave three CPs. • Complex 1 is a 3D entanglement. • Complex 2 or 3 is a 3D supramolecular structure based on different 2D layers. • Complex 2 exhibited good catalytic activity of methylene blue photodegradation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Novel heteroleptic lanthanide organic frameworks containing pyridine-2,5-dicarboxylic acid and in situ generated piperazine-2,5-dicarboxylic acid from piperazine: Hydrothermal synthesis and luminescent properties

Two novel 3D lanthanide metal-organic frameworks [Ln(pydc)(pip){sub 1/2}(H{sub 2}O] (Ln=Ce (1) and Pr (2), H{sub 2}pydc=2,5-pyridinedicarboxylic acid, H{sub 2}pip=2,5-piperazinedicarboxylic acid have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffractions (PXRD), and single-crystal X-ray diffractions. Field emission scanning electron microscopy (FESEM) was used for morphological analysis. Complexes are isostructural and feature interesting 3D frameworks. Both compounds crystallize in the monoclinic system, space group P2{sub 1}/c. Structural analyses of 1 and 2 show that Ln{sup 3+} ions connect with each other through H{sub 2}pydc and H{sub 2}pip. To the best of our knowledge, they are the first heteroleptic lanthanide polymers obtained through in situ 2,5-piperazinedicarboxylic acid syntheses. Moreover, thermal and luminescent properties of the compounds have been investigated. - Graphical abstract: Two novel 3D lanthanide metal-organic frameworks have been synthesized under hydrothermal conditions. Luminescent properties of the compounds in different temperatures have been also investigated. - Highlights: • New cerium and praseodymium coordination polymers based on N-O-bifunctional ligands have been synthesized In situ hydrothermal decarboxylation. • 2,5-pyridinedicarboxylic acid and piperazine were used as ligands. • In situ hydrothermal decarboxylation and formation of ligands were observed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗