Structural and spin-glass properties of single crystal JeffJ_{eff} = 1/2 pyrochlore antiferromagnet NaCdCo2_2F7_7 : correlating TfT_f with magnetic-bond-disorder

Weak bond disorder disrupts the expected spin-liquid ground-state of the ideal $S$ = 1/2 Heisenberg pyrochlore antiferromagnet. Here we introduce a single crystal study of the structural and magnetic properties of the bond-disordered pyrochlore NaCdCo$_2$F$_7$. The magnetic susceptibility appears isotropic, with a large negative Curie-Weiss temperature ($\theta_{CW}$ = -108(1) K), however no magnetic order is observed on cooling until a spin-glass transition at $T_f$ = 4.0 K. AC-susceptibility measurements show a frequency-dependent shift of the associated cusp in $\chi$ at $T_f$, that can be fitted well by the empirical Vogel-Fulcher law. The magnetic moment of $\mu_{eff}$ = 5.4(1) $\mu_{B}$/Co$^{2+}$ indicates a significant orbital contribution and heat capacity measurements show that down to 1.8 K, well below $T_f$, only $S_{mag}$ ~2/3 Rln(2) of the magnetic entropy is recovered, suggestive of residual continued dynamics. Structural and magnetism comparisons are made with the other known members of the Na$A$Co$_2$F$_7$ family ($A$ = Ca$^{2+}$, Sr$^{2+}$), confirming the expected relationship between spin-glass freezing temperature, and extent of magnetic bond disorder brought about by the size mismatch between A-site ions

Crystal structure of 4-bromo-3-nitro-1H-pyrazole-5-carboxylic acid monohydrate, C4H2N3BrO4·H2O

C4H2N3BrO4·H2O, monoclinic, P21/c (no. 14), a = 7.177(2) Å, b = 10.999(3) Å, c = 10.414(3) Å, β = 100.145 (11) °, V = 809.3(4) Å3, Z = 4, Rgt (F) = 0.0379, wRref (F2) = 0.0714, T = 200K © 2023 the author(s), published by De Gruyter, Berlin/Boston

Sr-bearing high-pressure tourmaline from the Kreuzeck Mountains, Eastern Alps, Austria

A detailed investigation was conducted on high-pressure (~1.4 GPa) tourmaline from an Eoalpine mafic eclogite, which occurs in the Kreuzeck Mountains, Eastern Alps, Austria. Tourmaline from this locality contains the highest amount of Sr²⁺ (up to 0.68 wt% SrO) known to date. The space group is R3m with unit-cell parameters a = 15.944(1), c = 7.202(1) Å, V = 1585.5(3) ų. Analyses by a combination of electron microprobe, optical absorption spectroscopy and crystal-structure refinement (R1 = 1.31%) result in the structural formula ^X(Na_(0.85)Ca_(0.08)Sr_(0.06)K_(0.01))_(Σ1.00)^Y(Mg_(1.68)Al_(0.70) Fe_(0.37)³⁺Ti_(0.10)⁴⁺Fe_(0.11)²⁺Ca_(0.03)Cr_(0.01)³⁺)_(Σ3.00)^Z (Al_(5.15)Mg_(0.80)Fe_(0.05)³⁺)_(Σ6.00)^T(Si_(5.82)B_(0.10)Al_(0.08)O_(18)) (BO₃)₃^V(OH)₃^W [O_(0.45)(OH)_(0.35)F_(0.20)]. The T site contains mainly Si and additionally small amounts of B and Al. According to optical absorption spectroscopy (using the band near 1120 nm), the Fe³⁺/Fe ratio is 79 ± 2%, suggesting that this high-pressure tourmaline crystallized under oxidizing conditions. It has a significant oxy-dravite component. A near-rim zone contains 0.6 wt% Cr₂O₃, 0.5 wt% PbO₂, 0.2 wt% NiO and 0.1 wt% V₂O₃. Only a small F content was found by structure refinement. There is no evidence for significant X-site vacancy in the investigated tourmaline zones. We assume that the original boron source for tourmaline crystallization in the eclogite, i.e. tourmaline-bearing pegmatites in the country-rock, were influenced by a Sr-bearing marble

Crystal structure of 4-bromo-2-(1H-pyrazol-3-yl)phenol, C9H7BrN2O (vol 232, pg 507, 2017)

C9H7BrN2O, monoclinic, C2/c (no. 15), a = 16.255(3) angstrom, b = 4.4119(9) angstrom, c = 25.923(5) angstrom, beta = 107.99(3)degrees, V = 1768.2(7) angstrom(3), Z = 8, R-gt(F) = 0.0450, wR(ref)(F-2) = 0.0960, T = 150 K

Preparation, Thermal Analysis and Spectral Characterization of the 1:1 Complexes of Mercury(II) Halides and Pseudohalides with 3,4,5,6-Tetrahydropyrimidine-2-thione. Crystal Structures of Bis(3,4,5,6-tetrahydropyrimidine-2-thione-S)mercury(II) Tetrachloro and Tetrabromomercurate(II)

Mercury(II) complexes of the type HgX2(H4pymtH) (X = Cl-, Br-, I-, SCN-, CN-; H4pymtH = 3,4,5,6-tetrahydropyrimidine-2-thione) have been obtained and structurally characterized by X-ray diffraction, IR, 1H and 13C NMR spectroscopy. Single crystal X-ray structure analysis was performed for the chloro and bromo complexes, which were found to be isostructural. Their crystal structures consist of [Hg(H4pymtH)2]2+ complex cations and [HgX4]2- complex anions interconnected by Hg⋅⋅⋅X contacts into puckered sheets. The crystal structure of H4pymtH has been redetermined to greater accuracy. In solution NMR spectra of complexes, the greatest complexation effects were found on the 13C Chemical shift of the thio-keto-carbon atom and on the 1H Chemical shift of the NH protons

Preparation, thermal analysis and spectral characterization of the 1 : 1 complexes of mercury(II) halides and Pseudohalides with 3,4,5,6-Tetrahydropyrimidine-2-thione. Crystal structures of bis(3,4,5,6-tetrahydropyrimidine-2-thione-S)mercury(II) tetrachloro and tetrabromomercurate(II)

Mercury(II) complexes of the type HgX2(H(4)pymtH) (X Cl- Br I-, SCN-, CN-; H(4)pymtH = 3,4,5, 6-tetrahydropyrimidine-2-thione) have been obtained and structurally characterized by X-ray diffraction, IR, H-1 and C-13 NMR spectroscopy. Single crystal X-ray structure analysis was performed for the chloro and bromo complexes, which were found to be isostructural. Their crystal structures consist of [Hg(H(4)pymtH)(2)](2+) complex cations and [HgX4](2-) complex anions interconnected by Hg . . .X contacts into puckered sheets. The crystal structure of H(4)pymtH has been redetermined to greater accuracy. In solution NMR spectra of complexes, the greatest complexation effects were found on the C-13 chemical shift of the thioketo-carbon atom and on the H-1 chemical shift of the NH protons

Synthesis, crystal structure and biological activity of copper(II) complex with 4-nitro-3-pyrazolecarboxylic ligand

The reaction of 4-nitro-3-pyrazolecarboxylic acid and Cu(OAc)2⋅H2O in ethanol resulted in a new coordination compound [Cu2(4-nitro-3- -pzc)2(H2O)6]2H2O (4nitro-3pzc = 4-nitro-3-pyrazolecarboxylate). The compound was investigated by means of single-crystal X-ray diffraction and infrared spectroscopy. The biological activity of the complex was also tested. In the crystal structure of [Cu2(4nitro-3-pzc)2(H2O)6]2H2O, the Cu(II) ion is in a distorted [4+2] octahedral coordination due to the Jan–Teller effect. A survey of the Cambridge Structural Database showed that the octahedral coordination geometry is generally rare for pyrazole-bridged Cu(II) complexes. In the case of Cu(II) complexes with the 3-pyrazolecarboxylato ligands, no complexes with a similar octahedral coordination geometry have been reported. Biological research based on determination of the inhibition effect of the commercial fungicide Cabrio top and the newly synthesized complex on Ph. viticola were performed using the phytosanitary method

Inhibition of Na+/K+- and Ca2+-ATPase activities by phosphotetradecavanadate

Polyoxometalates (POMs) are promising inorganic inhibitors for P-type ATPases. The experimental models used to study the effects of POMs on these ATPases are usually in vitro models using vesicles from several membrane sources. Very recently, some polyoxotungstates, such as the Dawson anion [P2W18O62]6-, were shown to be potent P-type ATPase inhibitors; being active in vitro as well as in ex-vivo. In the present study we broaden the spectrum of highly active inhibitors of Na+/K+-ATPase from basal membrane of epithelial skin to the bi-capped Keggin-type anion phosphotetradecavanadate Cs5.6H3.4PV14O42 (PV14) and we confront the data with activity of other commonly encountered polyoxovanadates, decavanadate (V10) and monovanadate (V1). The X-ray crystal structure of PV14 was solved and contains two trans-bicapped α-Keggin anions HxPV14O42(9-x)-. The anion is built up from the classical Keggin structure [(PO4)@(V12O36)] capped by two [VO] units. PV14 (10 μM) exhibited higher ex-vivo inhibitory effect on Na+/K+-ATPase (78%) than was observed at the same concentrations of V10 (66%) or V1 (33%). Moreover, PV14 is also a potent in vitro inhibitor of the Ca2+-ATPase activity (IC50 5 μM) exhibiting stronger inhibition than the previously reported activities for V10 (15 μM) and V1 (80 μM). Putting it all together, when compared both P-typye ATPases it is suggested that PV14 exibited a high potential to act as an in vivo inhibitor of the Na+/K+-ATPase associated with chloride secretion.FCT, Foundation for Science and Technology (UID/Multi/04326/2013) ; (SFRH/BSAB/129821/2017) Austrian Science Fund (FWF) (P27534) (M2200) Council of Scientific & Industrial Research (CSIR) (01(2906)/17/EMR-II) Grant Agency of the Ministry of Education of the Slovak Republic and Slovak Academy of Sciences VEGA (1/0507/17)info:eu-repo/semantics/publishedVersio

Fatty Acid Copper(II) Carboxylates with Nicotinamide - Characterization and Fungicidal Activity. Crystal Structures of Two Heptanoate Forms and Nonanoate

Several new compounds of the composition Cu2(OOCCnH2n+1)4 (nia)2 (nia = nicotinamide; n = 6 to 11) were synthesized, characterized and tested for fungicidal activity. Crystal structure determinations revealed dinuclear structures of the copper(II) acetate hydrate type for compounds [Cu2(OOCC6H13)4(nia)2]-A (1A), [Cu2(OOCC6H13)4(nia)2]-B (1B) and [Cu2(OOCC8H17)4(nia)2] (3). Other applied characterization methods indicate dimeric structures for ali synthesized compounds [μeff (298 K) = 1.43-1.50 BM; characteristic band in UV-Vis spectra in the region λ = 350-400 nm]. The same conclusion may also be deduced from the IR (Δ = νasym(COO-) - νsym(COO-) = 183-189 cm-1) and EPR spectra, though some differences were observed for heptanoate modification 1A, probably due to a different hydrogen bonding scheme. Screening for fungicidal activity against the wood-rotting fungus Trametes versicolor (L. ex Fr.) Pilat shows that the compounds dissolved in DMSO completely stop mycelium growth at a concentration of 1.0 × 10-3 mol L-1. Some of them (n = 8, 9, 10) show strong activity also in more diluted Solutions (1.0 × 10-4 mol L-1)