α-Thioureidoalkylation of 4-alkyl- and 4-phenylthiosemicarbazides

Previously unknown 1,3-dialkyl-4,5-bis[4-alkyl(phenyl)thiosemicarbazido]imidazolidine-2-thiones and 4,5,7-trialkylperhydroimidazo[4,5-e]-1,2,4-triazine-3,6-dithiones have been synthesized by the α-thio-ureidoalkylation of 4-alkyl(phenyl)thiosemicarbazides using 1,3-dialkyl-4,5-dihydroxyimidazolidine-2-thiones.     

Synthesis and oxidative polycondensation of 4, 4−diethynylbiphenyl

Summary 4,4-Diethynylbiphenyl was synthesized. By polycondensing it an oligomer with alternating biphenyl (-4,4) and diacetylene chains was obtained.     

Corrected values of osmotic and activity coefficients of aqueous NaTcO4 and HTcO4 at 25°C

Published isopiestic molalities for aqueous NaTcO₄ and HTcO₄ solutions at 25°C have been reexamined. Our calculations indicate that published smoothed values of the osmotic coefficients and mean molal activity coefficients _± of NaTcO₄ are substantially in error, by up to 100% for and 300% for _±. Published smoothed values of and _± for HTcO₄ solutions are in somewhat better agreement with the input data, but the reported are sometimes higher and sometimes lower than experimental values, by up to 6%. Consequently, we have reanalyzed isopiestic data for these two systems, and find that errors arose in representing the data mathematically. We report parameters for an extended form of the specific ion interaction equations and for Pitzer's equations, and corrected values of and _± are tabulated for aqueous NaTcO₄ and HTcO₄.     

Synthesis and application of 4-dipropylaminodiazabenzene-4′-isothiocyanate to the derivatization and chromatographic separation of biogenic amines

Summary The physicochemical properties of biogenic monoamines, their polar character, lability and trace amounts found in the biological material create great analytical difficulties in their identification and separation. The selective chromatographic separation of those amines is greatly facilitated by their derivatization [1]. Based on theoretical considerations, 4-dipropylaminodiazabenzene-4′-isothiocyanate (DPABITC) was synthetized and applied to the preparation of thiocarbamoyl derivatives of the amines. The coloured derivatives were separated by TLC. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

IR absorption spectra and structure of 4-cyano-4′,-p-alkoxybiphenyls

The IR absorption spectra of 4-cyano-4,-p-alkoxybiphenyls were investigated experimentally (in the range 100–3200 cm^–1 at 100–400 K), and they were interpreted on the basis of a calculation of the frequencies, forms, and intensities of the normal vibrations of various conformers of the propyloxycyanobiphenyl molecule. Temperature and phase changes in the parameters of the IR spectrum are explained by a change in the conformational composition and intermolecular interactions in the investigated liquid crystals.Institute of Physics, Ukrainian Academy of Sciences. Saratov State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 105–111, January–February, 1993.     

Crystal and Molecular Structure of 4-Phenyl-cyclohexanone Semicarbazone

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Synthesis and Structure of 4—Nitrobenzaldehyde Thiosemicarbazone

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Synthesis and Structure of Ag_3PSe_4

The title compound Ag3PSe4 was synthesized by the reaction of Ag powder,P2Se5 and Se in a molar ratio of 1:1:1 at 500℃ and structurally characterized by X-ray crystallography.The crystal belongs to orthorhombic,space group Pmn21 with cell parameters:a=7.689(4),b=6.660(3),c=6.379(4)A,V=326.7(3)A^3,Z=2,Dc=6.816g/cm^3,Mr=670.42,F(000)=584,μ=31.302mm^-1,R=0.0606,wR=0.1289 and S=1.012,The 3-D structure can be regarded as constructed from the stacking of puckered Ag-P-Se honeycomb-like sheets along the c direction,in which the Ag,P and Se atoms are bonded to each other to form a chair-like six-membered ring,and the rings then build the sheets by sharing edges.     

Photophysics properties of 4-formacyl-triphenylamine and 4,4''''-bisformacyl-triphenylamine

The photophysical processes of 4-formacyl-triphenylamine (FTA) and 4,4'-bisformacyl-triphenyl-amine (BTA) have been studied. The fluorescences of FTA and BTA with donor (triamine) and acceptor (formacyl) moieties show the twisted intramolecular charge transfer (TICT) emission in polar solvents and photoinduced charge transfer (ICT) emission in nonpolar solvents. These could be supported by the solvent effect, temperature effect and the quenching process by strong electron-deficient compounds.     

Synthesis and antibacterial activity of 4“-O-carbamoyl analogs of clarithromycin

<正>A series of novel 4"-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.     

Standard enthalpies of formation of 4-methylbiphenyl and 4,4′-dimethylbiphenyl

The energies of combustion of 4-methylbiphenyl and 4,4′-dimethylbiphenyl in the crystal state were measured in a precision calorimeter equipped with a self-sealing bomb at 298.15 K. The enthalpies of vaporization of these substances were measured in an isothermal heat-conducting Calvet microcalorimeter. Standard enthalpies of formation were calculated for 4-methylbiphenyl and 4,4′-dimethylbiphenyl in the crystal, liquid, and gas states.     

Synthesis and Biological Activity of Novel Spin Labeled Derivatives of 4′-Demethyl-4-deoxypodophyllotoxin

Seven novel spin labeled derivatives of 4′-demethyl-4-deoxypodophyllotoxin with nitroxyl radicals(TMHPO and TMPRO) were prepared and their cytotoxic and antioxidative activities were tested. Their cytotoxic activities were tested against two tumor cell lines(A-549 and HL-60) in vitro. Among them, five compounds show higher inhibition activity against A-549 cells compared with the clinical drug VP-16(2) and parent compound 4′-demethyl-4-deoxypodophyllotoxin(DDPT, 6). Compounds 8, 10 and 13 show excellent inhibition activity against HL-60 cells. Furthermore, the antioxidative activities of them were tested. All the seven spin labeled compounds show stronger antioxidative activity compared with VP-16(2) and DDPT(6). The partition coefficients P of these derivatives were determined.     

Structure of Dimers and the Nature of Color in 4′-Nitro-4-dimethylaminoazobenzene Solutions

A mechanism is proposed for the formation of stable dimers of 4′-nitro-4-dimethylaminoazobenzene dye (4′-nitro-DAB)₂ in solution, the existence of which in a vapor phase was established in 1965. It is shown that (4′-nitro-DAB)₂ dimers are stable also in neutral and moderately acidic solutions. Their UV–Vis spectra are similar to the spectra of the same solutions of 4-dimethylaminoazobenzene (DAB) containing DAB₂ dimers as the ground state. Like DAB₂, (4′-nitro-DAB)₂ dimers are reversibly converted to di- and triprotonated dimers under conditions of low and moderate acidity. In the process, the yellow color of the initial solution changes to red. It is concluded that the great stability of the dimers in the liquid and vapor phases is due to their inter-monomer bonds being formed with the participation of electrons promoted from the sp²- orbitals of N-atoms in azo-groups N=N to the Rydberg 3s-orbitals of the N=N-group (Rydberg bonds). It is established that at high acidities, the triprotonated dimers (the red solution) decompose reversibly into diprotonated monomers (the yellow solution). Structural formulas are proposed for the protonated species.     

Ab initio quantum mechanical calculations of energy,geometry, vibrational frequencies and IR intensities of tetraphosphorus tetrasulphide, α-P4S4(D2d), and vibrational analysis of As4S4 and As4Se4

Geometry, vibrational frequencies and IR intensities are calculated for α-P₄S₄ by scaled quantum mechanical calculations at the 6-31G*/SCF and STO-3G*/SCF levels. For both basis sets the frequencies are scaled with factors close to or equal to those found for P₄S₃, and based on these results a revised assignment is proposed. The α-P₄S₄ force field is transferred to the isostructural As₄S₄ and As₄Se₄ molecules and rescaled, and based on a good fit to experimental frequencies a new assignment is also proposed for these compounds.     

Powder diffraction data and mesomorphic properties of 4-butyloxyphenyl 4′-decyloxybenzoate

Unit cell parameters calculated from X-ray powder diffraction data are presented for the crystalline phase of a liquid crystal 4-butyloxyphenyl 4′-decyloxybenzoate: a = 23.098 (4) Å, b = 5.974 (6) Å, c = 12.357 (10) Å, β = 121.5283 (788)°, unit-cell volume V = 1453.56 ų. Temperature dependent X-ray diffraction data confirmed the existence of smectic A and smectic C mesophases and a more ordered, tilted crystalline smectic phase. Possibility of existence of previously reported smectic B phase as well as another crystalline phase was refuted.     

Synthesis and Characterization of a Novel Zeolite CJS-4

A novel zeolite, denoted as CJS-4, has been synthesized from nonalkaline medium by using 4,4'-trimethylenebis(1-methylpiperidine) or 1,4-diazoniabicyclo(2,2,2) octane as template agent, respectively. The precursors were characterized by means of powder X-ray diffraction, scanning electron microscopy, thermal analysis, gas adsorption and high resolution solid state NMR of 13C and 29Si.     

Synthesis and Complexation Properties of Novel Biscalixarene Composed of Calix[4]arene and Thiacalix[4]arene Subunits

Biscalixarenes, as examples of higher order molecular architectures than normal calixarene derivatives, were studied extensively in the recent years due to they possess two calixarene cavities which have the potential for complexing with two guests in two…     

Synthesis and Characterization of Manganese Tetrafluoride β-MnF4

The crystal structure of β-MnF₄ has finally been elucidated. It crystallizes in the non-centrosymmetric space group R3c, no. 161, hR360, with the lattice parameters a = 19.390(3), c = 12.940(3) Å, V = 4213.3(14) ų, Z = 72, T = 100 K. It is a 4a × 4a superstructure of the VF₃ (FeF₃) structure type. The Mn atoms are coordinated octahedron-like by F atoms, of which two are bound terminal, while the other act as μ-bridging F atoms to other Mn atoms forming a three-dimensional infinite network structure which can be described by the Niggli formula ³_∞[MnF_4/2F_2/1]. Voids on the metal sites, which are occupied in the VF₃ structure, are grouped together in the shape of a “star” with approximate D_3h symmetry. We prepared β-MnF₄ photochemically according to the literature and obtained a phase-pure powder as evidenced by X-ray diffraction at room temperature. The lattice parameters are a = 19.566(3), c = 12.984(2) Å, V = 4304(1) ų. IR and Raman spectra recorded on the powder show that β-MnF₄ has also been obtained free of moisture, HF, and O₂⁺ containing compounds, however MnF₃ is likely present as a magnetic impurity. We observe thermal decomposition of MnF₄ to MnF₂ and not MnF₃.     

Thermochemical studies of 4-tert-butylbiphenyl and 4,4′-di-tert-butylbiphenyl

The standard massic energies of compounds of 4-tert-butylbiphenyl and 4,4′-di-tert-butylbiphenyl were measured at T = 298.15 K by static-bomb combustion calorimetry. The standard enthalpies of vaporization, fusion and sublimation were measured in a Calvet microcalorimeter, or by differential scanning calorimetry. The standard molar enthalpies of formation in the condensed and gaseous states were obtained from these data. The tert-butyl group increments for the substitution of one hydrogen atom in a position “4” in biphenyl molecule were calculated.