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71.
Alexei A. Belik Shinya Uji Eiji Takayama-Muromachi 《Journal of solid state chemistry》2005,178(11):3461-3463
Magnetic properties of quasi-one-dimensional S=1/2 Heisenberg antiferromagnet Sr2Cu(PO4)2 were investigated by temperature and field dependence of AC susceptibility down to 0.03 K. A sharp peak was observed at on the temperature dependence of AC susceptibility indicating long-range magnetic ordering. Taking into account the exchange constant, (Hamiltonian =J∑SiSi+1), the ratio kBTN/J is 0.06%. Sr2Cu(PO4)2 is, therefore, one of the best one-dimensional Heisenberg antiferromagnet known so far. 相似文献
72.
《Arabian Journal of Chemistry》2022,15(4):103712
Although recent decades have witnessed the synthesis of 1,3,4-thiadiazoles via phosphorus POCl3-promoted cyclization reaction, simultaneous access to 2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-oxadiazole analogs remains unexpected and elusive. Herein, a detailed regiocontrolled synthesis of 2-amino-1,3,4-thiadiazoles in good to high yields with good regioselectivities from readily available thiosemicarbazides using POCl3 was disclosed. Meantime, to establish a comprehensive structure–activity relationship, 2-amino-1,3,4-oxadiazole derivatives as single regioisomers were prepared via EDCI·HCl-triggered cyclization of the thiosemicarbazide intermediates. The in vitro anti-influenza assays proved that the selected compounds with the pyrazine/pyridine ring exhibited certain inhibitory activities against influenza A virus strains A/HK/68 (H3N2) and A/PR/8/34 (H1N1) in MDCK cells. Among them, N-(adamantan-1-yl)-5-(5-(azepan-1-yl)pyrazin-2-yl)-1,3,4-thiadiazol-2-amine (4j) was the most active compound, and exhibited favorable activity with EC50 values of 3.5 μM and 7.5 μM, respectively. In addition, the molecular docking results explained the reason why compound 4j had dual inhibitory activity and revealed the reasonable binding mode of this compound with the M2-S31N and M2-WT ion channels. This compound had the potential to be further developed as an anti-influenza drug. 相似文献
73.
TiO2 has been tested to be toxic to DNA under the photo-irradiation of ultraviolet A (UVA). However, in the dark conditions, after several days of treatment with TiO2 in aqueous solution, the interaction between TiO2 and two types of DNA was detected and the mechanisms were studied by the methods of gel-electrophoresis, IR spectroscopy and TEM. The results showed that the DNA would be bound to TiO2; the ratio of binding was related to the concentration and the treating time; the mechanism of binding is related to phosphate groups of DNA. Besides, DNA with different structure showed different degree of binding. These findings showed a new possible way through which the TiO2 nanoparticles interact with DNA. 相似文献
74.
The structure of 1-hydroxy-1,2,3-benzotriazolium diphenyl phosphate (HOBt/DPP) has been investigated by X-ray analysis. The compound crystallizes in the monoclinic space group P21/n with Z = 4 and the following lattice parameters: a = 11.711(2), b = 12.727(2) and c = 12.794(3) Å, β = 105.12(2)°, V = 1840.9(6) Å3. The structure was solved by direct methods and refined on F2 to R values of wR2 = 0.084 and R1 = 0.034 for 1985 observed reflections. HOBt/DPP has an ionic structure with very short OHO and NHO hydrogen bonds linking the different ions. Owing to these hydrogen bonds, infinite screw-shaped chains which are twisted parallel to the y-axis are formed. 相似文献
75.
Chao Chen Yu-Lin Yang Kun-Lin Huang Zhen-Hua Sun Wei Wang Zhuo Yi Yun-Ling Liu Wen-Qin Pang 《Polyhedron》2004,23(18):3033-3042
With a hydrothermal technique, a layered titanium phosphate with the formula Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16 (denoted TP-J2) has been prepared by treating the Ti/H3PO4/H2O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state 31P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å. = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip. 相似文献
76.
Marco Arfelli Giovanni Cossu Giulia Mattogno Carla Ferragina Maria Antonietta Massucci 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(2):161-170
X-ray photoelectron spectroscopy provides evidence that when [Cu(phen)2]2+(phen = 1,10-phenanthroline) is diffused between the layers of -zirconium phosphate, the complex species does not remain intact after intercalation, but some Cu-N bonds are broken, replaced with Cu-O bonds and the released nitrogen atoms can now interact with the PO3-OH groups of the host. XPS also provides evidence for coordination of the Cu2+ ions when they are diffused by ion exchange in the phenanthroline--zirconium phosphate intercalation compound. Although Cu2+ and phen are in a 1 : 1 molar ratio in the interlayer region of the host, so that a 1 : 1 coordination could be expected between the two species, the characteristic peaks of the uncoordinated phenanthroline, even though at a low intensity, are still present. The differences between the two Cu(II)-intercalation compounds are discussed. 相似文献
77.
Bis(fluoroalkyl)acrylic and methacrylic phosphate monomers, their polymers and some of their properties 总被引:1,自引:0,他引:1
Christopher M. Timperley Robert E. Arbon Michael Bird Stuart A. Brewer Malcolm W. Parry David J. Sellers Colin R. Willis 《Journal of fluorine chemistry》2003,121(1):23-31
Ten fluoromonomers of structure (RFO)2P(O)OCH2CH2OC(O)CRCH2 were made in 30-64% yield by treating the chloridates (RFO)2P(O)Cl with HOCH2CH2OC(O)CRCH2 in chloroform in the presence of triethylamine [RF=CF3CH2, C2F5CH2, C3F7CH2, C4F9CH2, C4F9CH2CH2 or C6F13CH2CH2; R H or Me]. The chloromonomer (CCl3CH2O)2P(O)OCH2CH2OC(O)CHCH2 was obtained analogously in 29% yield. Polymerisation of the acrylate monomers, but not the methacrylate monomers, could be effected using α-azoisobutyronitrile as a radical initiator. Acrylic polymers having CF3CH2O, CCl3CH2O and C6F13CH2CH2O side-chains were obtained as translucent rubbers. Specimens of cotton fabric were treated with solutions of the polymers, and average water and oil repellency ratings measured. Fabric coated with the polymer with the C6F13CH2CH2O side-chain afforded protection from penetration of the test liquids. Treated fabrics were subjected to the limiting oxygen index (LOI) test according to BS EN ISO 4589-2 (1999): this test determines the point at which a material just burns in a volumetric flow of oxygen and nitrogen. The treated fabrics were more fire-resistant (LOI 22-29%) than the untreated fabric (LOI 18%). Fabric coated with the CCl3CH2O-based polymer can be considered fire-retardant (LOI 29%). The fluoromonomers were tested for anti-acetylcholinesterase activity and were found to be poor enzyme inhibitors; they are predicted to possess low acute toxicity. 相似文献
78.
Kaloustian J. Pauli A. M. Pieroni G. Portugal H. 《Journal of Thermal Analysis and Calorimetry》2002,70(3):959-973
The human urinary calculi are mainly constituted by calcium oxalate, magnesium ammonium phosphate hexahydrate, and uric acid.
The ions or molecules are easily characterized by wet chemical methods. The difficulties appear in the differentiation of
the hydrates of calcium oxalate (monohydrate COM or Whewellite, and dihydrate COD or Weddelite). A high level of COD in the
urinary stones leads, often, inflammation, sharp pain and blood in urine. In the worse cases, they must be extracted by surgical
way. The identification of the main components of urinary calculi, the knowledge of the true number of water molecules bounded
to the calcium oxalate, and the determination of each hydrate in the mixture, are the interests of this memory. The thermal
analysis (simultaneous DTA-TG) was applied on thirty-three urinary calculi. The determination of the calcium oxalate hydrates
was confirmed by calorimetry (DSC).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
79.
The technique of diffusive gradients in thin films (DGT) is a newly developed analytical technique capable of measuring in situ concentrations of trace metals in the environment. The technique employs a thin film diffusive hydrogel (with well-defined diffusion properties) in contact with a binding phase capable of binding metal ions of interest. In this work, we demonstrate, for the first time, the use of a commercially available solid ion exchange membrane (Whatman P81) as the binding phase in DGT analysis. The cellulose phosphate-based Whatman P81 membrane is a strong cation exchange membrane. Its performance characteristics as a new binding phase in DGT measurement of Cu2+ and Cd2+ were systematically investigated. Several advantages over the conventional ion exchange resin-embedded hydrogel binding phases used in DGT were observed including simple preparation, ease of handling, and reusability. The binding capacities of the material to various metal ions were examined both collectively and individually. The binding phase preferentially binds to transition metal ions rather than matrix ions such as potassium, sodium, calcium and magnesium, which are competitive species in natural waters. Within the optimum pH range (pH 4.0-9.0), the maximum non-competitive binding capacities of the membrane for Cu2+ and Cd2+ were 3.22 and 3.07 μmol cm−2, respectively. The suitability of the new membrane-based binding phase for DGT applications was validated experimentally. The experimental results demonstrated excellent agreement with theoretically predicted trends. The measurement was not degraded after four consecutive reuses of the cellulose phosphate binding phase. 相似文献
80.
S. V. Klement’eva N. F. Cherepennikova V. V. Semenov A. I. Kirillov M. A. Lopatin O. V. Kuznetsova Yu. A. Kurskii A. A. Zaitsev L. G. Klapshina V. E. Duglas G. A. Domrachev 《Russian Chemical Bulletin》2007,56(11):2214-2224
A method for the synthesis of polyphosphosiloxane by the thermal condensation of an equimolar mixture of trimethyl phosphate
and (3-aminopropyl)triethoxysilane at 200 °C was developed. The reaction affords ethanol and polyphosphosiloxane-{Si(OEt)[(CH2)3NR1R2]-O-P(O)(OMe)-O}n-(R1 = H, Me; R2 = Me), whose composition and structure were confirmed by 1H, 13C, and 31P NMR spectroscopy, IR spectroscopy, and elemental analysis. The scheme of polymerization involving the intermediate formation
of methyl-and dimethylphosphoric acids and their condensation with ethoxysilanes was proposed. The calcination of the obtained
polyphosphosiloxane in vacuo at 350 °C results in the elimination of the amino groups and alkoxide substituents, and a spatially cross-linked polymer
is formed as an amorphous powder. Its further thermolysis at 600 and 1000 °C gives crystalline phosphosilicates Si5O(PO4)6 or SiP2O7. Their amorphous and crystalline samples were characterized by IR spectroscopy, X-ray diffraction analysis, and solid-state
13C and 31P spectroscopy.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2138–2148, November, 2007. 相似文献