Abstract The intermetallic compound LaNi11.8–11.4Si1.2–1.6 was synthesized by arc-melting and its crystal structure was determined using powder and single-crystal X-ray diffraction data. The compound adopts the cubic CaCu6.5Al6.5-type structure (space group Fm3‾$\bar{3}$c, Pearson code cF112, Z = 8), which is a partially ordered ternary derivative of the NaZn13 type: a = 11.256(4) Å, V = 1426.1(15) Å3, R = 0.0133, wR = 0.0285 for 93 reflections with I > 2 σ(I) for LaNi11.4Si1.6; a = 11.25486(8) Å, V = 1425.68(2) Å3, Rp = 4.17%, Rwp = 5.85%, RB = 3.44% for LaNi11.8Si1.2. One of its crystallographic positions (96i) is occupied by a mixture of Ni and Si atoms. The structure of this new silicide can be represented as a packing of Ni-centered icosahedra and La-centered snub cubes, which are packed in a CsCl-related manner.
CaFeO2Cl is a unique exception in the family of the iron oxyhalides. Its crystal structure is not related to the Ruddlesden-Popper phases as known for the other members, but contains layers of edge-sharing FeO2/2O3/3 pyramids without Fe-Cl contacts. The iron atoms form a distorted honeycomb substructure. Magnetization measurements on single crystals show an unexpected weak anisotropy and indicate antiferromagnetic ordering of the iron magnetic moments already at room temperature. Fe-57 Mossbauer spectra confirm the trivalent oxidation state of iron and the presence of magnetic order. DFT calculations using the LDA + U approach support a Mott-insulating antiferromagnetic ground state and indicate a Neel-type ordered antiferromagnetic state in the honeycomb layer. The band gap from optical measurements is 1.3 eV and agrees with the red-brown colour as well as with the theoretical calculations.
The substitution of Cu/Ag by lithium in complex thiospinels with the general formula Aᴵ₂BᴵᴵCᴵⱽ₃Xⱽᴵ₈ was achieved by ball milling and a subsequent annealing step in an atmosphere of H₂S. Four hitherto unknown compounds Li₂MSn₃S₈ with M = Mg, Mn, Fe, Ni were obtained without side phases and have been structurally investigated. From X-ray powder diffraction experiments, space group Fd3¯$\overline{3}$m and a spinel-type structure are suggested. In these so-called normal spinels, lithium occupies one eighth of the tetrahedral voids (Wyckoff position 8a) of the cubic closest packing of the sulfide ions whereas M and Sn can be found on one half of the octahedral voids (Wyckoff position 16d).
Binary lithium silicides play a crucial role in high energy density anode materials for rechargeable batteries. During charging processes of Si anodes Li₁₅Si₄ is formed as a metastable phase which has been stabilized through Li by Mg, Zn and Al substitution. Here we investigate Li by Zn substitution in the lithium-richest phase Li₁₇Si₄ and report on the particular site preference of Zn atoms since Zn is substituting Li atoms only on one out of 13 possible lithium sites. This site preference shows an interesting relation to the closely related phase Li₂₁Si₅ and thus Li₁₇₋e₋δZneSi₄ with e = 0.025(1) and δ = 0.033(1) can be considered as the missing link between the structures of Li₂₁Si₅ (= Li₄.₂₀Si) and Li₁₇Si₄ (= Li₄.₂₅Si).
Four solvent complexes of beryllium iodide were prepared by dissolving BeI₂ in N,N-dimethyl formamide (DMF), pyridine (Pyr), N-methyl pyrrolidone (NMP) and 2,6-dimethyl pyridine (2,6-lutidine, Lut). Their crystal structures were established from single crystal X-ray diffraction. For [Be(DMF)₄]I₂ a new modification is reported (monoclinic, space group P2₁/c, a = 12.491(2), b = 11.593(2), c = 15.310(3) A, β = 94.7073(6)°). In [Be(Pyr)₄]I₂ (monoclinic, space group C2/c, a = 17.8799(13), b = 7.6174(5), c = 18.2611(14) A, β = 113.508(4)°) and [Be(NMP)₄]I₂ (orthorhombic, space group Pbca, a = 13.941(5), b = 15.754(3), c = 24.634(7) A) homoleptic tetrahedral complex cations are formed, while the sterically demanding solvent ligand Lut yields a neutral complex with covalently bound iodine ligands [BeI₂(Lut)₂] (monoclinic, space group P2₁/c, a = 7.8492(9), b = 24.265(3), c = 27.037(3) A, β = 97.076(3)°). Their electrochemical stability with respect to their application as beryllium electrolytes for deposition of beryllium from solution is discussed.
: K 15 NaSn 5 F 36 crystallizes in the hexagonal crystal system with space group P 6 3 / m and lattice parameters of a = 1060.3(2) and c = 2011.9(4) pm. The unit-cell volume amounts to 1.9588(7) nm 3 . Its fundamental building blocks are quasi-isolated [SnF 6 ] 2− and [NaF 6 ] 5− octahedra, which are imbedded into a matrix of potassium cations. Within the structure, these units form a layer-like arrangement consisting either of mixed [SnF 6 ] 2− /[NaF 6 ] 5− or pure [SnF 6 ] 2− layers. The structural model was further confirmed by BLBS and CHARDI calculations.
The reaction of uranium tetrabromide with potassium cyanide in anhydrous liquid ammonia at room temperature leads to the formation of brown crystals of [U₂(CN)₃(NH₃)₁₄]⁵⁺ [KBr₆]⁵⁻ · NH₃. We determined the crystal structure of the compound by single crystal X-ray diffraction. To the best of our knowledge it contains the unprecedented spatially separated [KBr₆]⁵⁻ anion and presents the first uranium(IV) cyanide compound which forms a layer structure. The compound crystallizes in the trigonal space group P3m1 (No. 164) with a = 10.3246(13), c = 8.4255(17) A, V = 777.8(3) A³, Z = 1 at T = 100 K and is well described with the Niggli formula [U(CN)32(NH3)71]∞22[KBr61].$\mathop {} \limits_{\infty}^{2}{\left[ {{\rm{U}}{{({\rm{CN}})}_{{3 \over 2}}}{{({\rm{N}}{{\rm{H}}_3})}_{{7 \over 1}}}} \right]_2}\left[ {{\rm{KB}}{{\rm{r}}_{{6 \over 1}}}} \right].$
Abstract The isotypic triel borates Al5B12O25(OH) and Ga4InB12O25(OH) were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 12.0 GPa/1400 °C and 12.3 GPa/1200 °C, respectively. The crystal structures of both compounds, determined by single-crystal X-ray diffraction, constitute new representatives of the structure type M 5B12O25(OH) (M = Ga, In) crystallizing in the space group I41/acd. The presence of the hydroxyl groups was confirmed via single-crystal IR spectroscopy.
The potassium oxidofluoridostannate(IV) fluoride K5Sn2OF11 was synthesized via a solid-state route at T= 300 degrees C in arc-weldeded copper ampoules. It crystallizes in the orthorhombic system in the acentric space group Ama2 (no. 40) with a unit cell volume of V=2.5727(4) nm(3). The cell parameters are a=1758.3(2), b =2452.3(2) and c= 596.7(1) pm. As a main structural motif, K5Sn2OF11 exhibits two different kinds of dinuclear [Sn2OF11](5-) units, which are embedded into a matrix consisting of potassium cations and fluoride anions. The substance was characterized by single-crystal and powder X-ray diffraction, as well as by FT-IR spectroscopy.
The synthesis and structural characterization of the new olefinic complex [Rh(η⁵-C₅H₅)(coe)(PtBu₂H)] (2, coe = cis-cyclooctene) is reported. The title compound was easily prepared in good yield by a thermolytic approach using [Rh(η⁵-C₅H₅)(coe)₂] (1) and the secondary phosphane in toluene under reflux conditions. The compound 2 has been characterized by NMR spectroscopy and microanalysis. Single crystals of 2 were grown from n-hexane and the molecular structure has been established by X-ray diffraction.
Abstract The salt [NHEt3][Re(I)(quinaldate)(CO)3Cl] was obtained by the reaction of Re(CO)5Cl with quinaldic acid and triethylamine in toluene. The crystal structure analysis of this salt revealed the presence of the complex anion [Re(quinaldate)(CO)3Cl]−, with the d 6 Re(I) metal center in a pseudo-octahedral environment. The electronic spectra in absorption and emission exhibit bands which are attributed to quinaldate IL and CT transitions at comparable energies. The longest-wavelength emission originates from a Re(I) to quinaldate MLCT triplet, which can be quenched in solution by oxygen or triethylamine.
The new phosphor RbKLi2[Li3SiO4](4):Eu2+ was synthesized by different high-temperature solid-state reactions. It is accessible from the alkali metal carbonates, SiO2, and Eu2+ as a luminous active cation either in closed tantalum ampoules or by conventional solid-state reaction in nickel crucibles, under a constant flow of forming gas. The structure of the thereby received rod-shaped crystals was solved and refined on the basis of single crystal X-ray diffraction data. The compound crystallizes isostructurally to CsKNa2[Li3SiO4](4) and forms a highly condensed network of LiO4 and SiO4 tetrahedra [I4/m (no. 87), Z= 2, a= 10.9508(6) and c= 6.3334(3) angstrom]. It is a new member of the recently discovered family of alkali lithosilicate phosphors. Under excitation with UV to blue light, the compound exhibits interesting luminescence properties. Depending on the mode of synthesis, either green or blue luminescence of the samples is observed. Both emission profiles can be described as ultra-narrowbanded, since the full width at half maximum (fwhm) is below 0.2 eV. The green phosphor shows an emission maximum at 532 nm with a fwhm of 43.5 nm (0.193 eV) and the blue one at 474 nm with a fwhm of 24.8 nm (0.137 eV). Furthermore, the material presented here allows a more detailed localization of the luminescence center inside the structure, which may allow a better understanding of the luminescence properties of many other alkali lithosilicate phosphors.
Rod-shaped single crystals of Sr4Pt10In21 were prepared from the elements in glassy-carbon crucibles in a high-frequency furnace. The structure of Sr4Pt10In21 was refined from single-crystal X-ray diffractometer data: C2/m, Ho4Ni10Ga21 type, a = 2322.62(7), b = 450.27(2), c = 1958.09(7) pm, beta = 133.191(3)degrees, wR = 0.0464, 3200 F-2 values and 107 variables. The three-dimensional [Pt10In21](delta)-polyanionic network is stabilized through substantial Pt-In (269-313 pm Pt-In) and In-In (294-362 pm In-In) bonding. All platinum atoms have slightly distorted tricapped trigonal prismatic coordination and the two crystallographically independent strontium atoms are located in penta-capped pentagonal prisms.
Abstract Two compounds in the Sc-Co-In system were obtained by arc-melting of the pure metals and their crystal structures have been determined using single crystal X-ray diffraction data. The structure of Sc3Co1.64In4 (space group P6̅, а=7.6702(5), c=3.3595(2) Å, Z=1, R 1=0.0160, wR 2=0.0301) belongs to the Lu3Co2− x In4 type structure, which is closely related to the ZrNiAl and Lu3CoGa5 types. The structure of Sc10Co9In20 (space group P4/nmm, а=12.8331(1), c=9.0226(1) Å, Z=2, R 1=0.0203, wR 2=0.0465) belongs to the Ho10Ni9In20 type, which is closely related to HfNiGa2.
Plant growth-promoting bacteria that are also capable of suppressing plant pathogenic fungi play an important role in sustainable agriculture. There is a critical need for conducting research to discover, characterize and evaluate the efficacy of new strains of such bacteria in controlling highly aggressive plant pathogens. In this study, we isolated endophytic bacteria from medicinal plants of Bangladesh and evaluated their antagonistic capacity against an important phytopathogenic fungus Sclerotinia sclerotiorum. Growth-promoting effects of those isolates on cucumber and rice seedlings were also assessed. Among 16 morphologically distinct isolates, BDR-2, BRtL-2 and BCL-1 significantly inhibited the growth of S. sclerotiorum through induction of characteristic morphological alterations in hyphae and reduction of mycelial dry weight. When cucumber and rice seeds were treated with these endophytic bacteria, seven isolates (BCL-1, BDL-1, BRtL-2, BRtL-3, BDR-1, BDR-2 and BBoS-1) enhanced seed germination, seedling vigor, seedling growth and number of roots per plant at a varying level compared to untreated controls. All isolates produced high levels of indole-3-acetic acid (6 to 63 μg/mL) in vitro. Two most potential isolates, BDR-2 and BRtL-2, were identified as Bacillus amyloliquefaciens and B. subtilis, respectively, based on the 16S rRNA gene sequencing. These results suggest that endophytic Bacillus species from native medicinal plants have great potential for being used as natural plant growth promoter and biopesticides in sustainable crop production.
Abstract Despite the well-documented benefits of Combretum fragrans in Cameroon, only few scientific works have been done on it. In this study we isolated eight compounds from the leaves extract of C. fragrans: velutin (1), belamcanidin (2), cirsilineol (3), cirsimaritin (4), 3β-acetoxy-20,24-epoxy-11,25-hydroxy-dammarane (5), combretin A (6), combretin B (7) and a mixture of arjunolic acid (8a) and asiatic acid (8b). Compounds 6 and 7 presented potent anti-inflammatory, antioxidant and antidiabetic activities. Compounds 1, 3, 5 and the mixture of 8a and 8b were significantly active, and compounds 2 and 4 presented moderate activity for reactive oxygen species inhibitory and free-radical scavenging. All compounds were isolated using chromatographic techniques; their structures were elucidated by spectroscopic techniques and their spectroscopic data compared with those of the literature. Anti-inflammatory activity was evaluated via the oxidative burst assay using a luminol-amplified chemiluminescence technique, antioxidant activity by free-radical scavenging activity (DPPH) and antidiabetic activity via α-glucosidase inhibition. All of the isolated compounds (1–8) were reported to exhibit significant antioxidant activity. Compounds 1, 3, and 5–8 exhibited potent chemiluminescence inhibition effect, and only compounds 6 and 7 inhibited α-glucosidase. Thus, C. fragrans can be used as an effective natural source of anti-inflammatory, antioxidant and antidiabetic compounds.
Garcinia mangostana L. (the queen of fruits, mangosteen, family Guttiferae) is a wealthy source of xanthones. The CHCl3 soluble fraction of the air-dried pericarps of G. mangostana provided a new xanthone: mangostanaxanthone VII (5), along with four known xanthones: mangostanaxanthones I (1) and II (2), gartanin (3) and γ-mangostin (4). The structural verification of these metabolites was achieved by different spectral techniques, including UV, IR, 1D and 2D NMR and HRESIMS. The new metabolite was assessed for cytotoxic potential, using sulforhodamine B (SRB) assay towards the A549 and MCF-7 cancer cell lines. Moreover, its antimicrobial effects were evaluated against various bacterial and fungal strains, using agar disc diffusion assay. Mangostanaxanthone VII showed moderate cytotoxic activity against the A549 and MCF7 cell lines with IC50s 26.1 and 34.8 μM, respectively, compared with doxorubicin (0.74 and 0.41 μM, respectively).
The first mixed germanato-antimonato derivative of the {V14E8O42 } (E= semi-metal) cluster archetype has been synthesized under hydrothermal conditions and isolated as {Ni(phen)(3)}(2)[(alpha-V-14(IV) (Sb5Ge3O42)-Ge-IV-O-lV(OH)(3)(H-2 O)] center dot approximate to 16H(2)O (phen =1,10-phenanthroline). In the cluster anion, seven of the eight hetero-metal positions are occupied by disordered Ge/Sb atoms, while one position is fully occupied by Sb atoms. The [V14Sb5Ge3O42 (OH)(3)(H2O)](6-) anions are arranged in pairs with remarkably short inter-cluster Sb center dot center dot center dot O contacts. Bond valence sum calculation strongly suggests that the Sb center dot center dot center dot O contact must be taken into account as a weak bond. The magnetic properties are dominated by strong intra-cluster antiferromagnetic exchange interactions, and the cluster anion is magnetically quasi-isolated from the spins of the Ni2+ complex cations.
Abstract A new zinc(II)-based coordination polymer {[Zn(5-fip)(tdbpy)]·(DMF)}n (1) {5-H2fip=5-fluoroisophthalic acid, tdbpy=4,4′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)bispyridine, DMF=dimethylformamide} has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that complex 1 shows a unique two-dimensional network architecture containing single-stranded [Zn(5-fip)]n and double-stranded helical [Zn(tdbpy)]n chains. The thermal and luminescence properties of complex 1 have also been studied.
Abstract Baltic amber shows a greenish photoluminescence upon UV illumination. When amber is dissolved in organic solvents such as ethanol, an emission spectrum is observed, which resembles that of pyrene. At higher concentrations, pyrene undergoes an aggregation, which shifts the emission to longer wavelength. In solid amber, an analogous aggregation apparently takes place. Depending on the size of the solid amber particles, a bluish (λ max=450 nm) to greenish (λ max=480 nm) luminescence appears.
