化学修饰1，4，7，10-四氮杂环十二烷提高铼酸化合物的相变温度

通过碘甲烷对1,4,7,10-四氮杂环十二烷（cyclen）进行化学修饰得到甲基取代的N-甲基-1,4,7,10-四氮杂环十二烷（Me-cyclen）。将cyclen和Me-cyclen与HReO₄以1∶2的比例进行反应,分别获得化合物（cyclen）（ReO₄）₂（1）和（Me-cyclen）（ReO₄）₂（2）。差示扫描量热法和介电研究发现化合物1和2具有可逆的相变,相变温度为324 K （1）和384 K （2）。以上研究表明：通过对环状有机胺进行化学改性,在降低分子对称性同时可以显著提高该有机-无机杂化材料的相变温度。     

Biotransformation of 20(R)-panaxatriol by the fungus Aspergillus flavus Link AS 3.3950

Microbial transformation of 20(R)-panaxatriol by the fungus Aspergillus flavus Link AS 3.3950 was performed. Four new (1–4), along with two previously reported metabolites (5 and 6), were obtained. Their chemical structures were elucidated on the basis of extensive spectroscopic analyses. Furthermore, the inhibitory effects of those compounds on K562/ADR, Du-145, Hela, MCF-7 and HepG2 cell lines were evaluated by MTT assay. Among them, compound 15β-hydroxy-20(R)-panaxatriol (4) exhibited selective inhibitory effects on human leukaemic progenitor cells K562/ADR through arresting cell cycle, which was associated with obvious decrease of cyclin B1, cyclin D1 and cyclin-dependent kinase (CDK) 1/2/4/6 protein expression.     

Syntheses,crystal structures,and properties of two molecular double-supporting polyoxotungstates

Two molecular double-supporting polyoxotungstates [SiW₁₂O₄₀{M(phen)₂H₂O}₂] · nH₂O (phen = 1,10′-phenanthroline, M = Mn 1, n = 2; M = Co 2, n = 3) were synthesized hydrothermally and characterized by elemental analyses, IR, TG, and X-ray single-crystal diffraction. The variable-temperature magnetic susceptibilities were measured at 2–300 K. The double-supporting polyoxotungstate molecule consists of a Keggin-type dodecatungstosilicate anion and a pair of transition metal complex fragments which are covalently linked to opposite sides of the Keggin anion. The transition metal ion locates in the center of a distorted octahedron. Multiple H-bonding interactions are observed between the coordinated waters of the transition metal complex fragments and terminal oxygen atoms of Keggin units and also between the bridging oxygen atoms of Keggin units and the lattice waters, which creates one-dimensional chains or two-dimensional layers. Between the layers or chains there are weak CH···O hydrogen bonding interactions and van der Waals forces. The molecular double-supporting polyoxotungstosilicate begins to decompose at ca. 500 °C. The variable-temperature magnetic behavior of 1 shows weak antiferromagnetic characteristics with a small value of θ = −0.289 K.     

Influence of Temperature on Molecular Dipole Orientation in the Binary Mixture of Polar-Nonpolar Liquids

Abstract

The excess correlation factor in the binary mixture of polar liquid (i.e., i-butanol and t-butanol) in the nonpolar solvent (i.e., benzene, tetrachloromethane, n-heptane) has been evaluated at 301°K,307°K,313°K and 318°K. An extensive study has been made on the influence of temperature on the orientation of molecular dipoles in the solution with the help of the excess correlation factor.     

IR spectroscopic study of allylperoxy radical and products of its phototransformations in the Ar matrix

Matrix IR spectra of an allylperoxy radical (1) obtained by co-condensation of allyl radicals and molecular oxygen into an argon matrix at 12 K have been studied. The bands observed in the matrix IR spectrum are assigned to normal vibrations on the basis of ab initio calculations of radical1 and its isotope-substituted analog CA 18_{O 2} (1a). The band at I128.6 cm^–1 is assigned to the stretching vibration of the 0-0 bond. The products of photodecomposition of radical1 under UV irradiation ( > 248 nm) have been studied. A vinylacyl radical (2) with a characteristic high vibrational v(C=0) frequency of 1823.I cm -1 has been observed among the products of photolysis of1. According to the data of quantum chemical calculations, some delocalization of a free electron between an oxygen atom and two C atoms is observed in radical 2.Preliminary results were presented at the XII International Conference on Physical Organic Chemistry (Padova, Italy) in 1994.¹⁵ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. I, pp. 109–116, January, I996.     

Dodecanuclear water cluster in bowl: microwave-assisted synthesis of a heptanuclear cobalt(II) cluster

A heptanuclear double-bowl-like cluster [Co₇(mmp)₆(OH)₆]₂·(ClO₄)₂·12H₂O (1·12H₂O, Hmmp is 2-methoxy-6-methyliminomethyl-phenol) has been synthesized through the microwave-assisted reaction of Co(ClO₄)₂·6H₂O with 2-hydroxy-3-methoxy-benzaldehyde (Hhmb) and methylamine in mixed solvent (acetonitrile : distilled water = 9 : 1) for 29 min. 1·12H₂O was heated until 180 °C and it formed a non-water complex [Co₇(mmp)₆(OH)₆]₂·(ClO₄)₂ (1). The core of 1·12H₂O can be described as a double bowl, while the dodecanuclear water cluster stands on the bowl. Magnetic investigations show that 1·12H₂O and 1 display ferromagnetic interaction between cobalt ions. Moreover, 1 shows single molecular magnet behavior under 2 K. Magnetic studies indicate that hydrogen bond plays a vital role in transferring magnetic exchange effects.     

Physicochemical Properties of Acetonitrile-Butan-1-Ol and Acetonitrile-Butan-2-Ol Mixtures

Abstract

The densities (d₁₂ ) and relative permittivities (?¹²) of liquid binary mixtures of acetonitrile-butan-l-ol and acetonitrile-butan-2-ol were measured at 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K, as well as refractive indices (n ^D ₁₂) at 298.15 K and surface tensions (σ₁₂) at 293.15 K, 298.15 K and 303.15 K. From all these data, the molar volumes (V _m ), apparent molar volumes (V _{i, φ}), temperature coefficients of relative permittivities (α₁₂) and surface tensions (k) and their deviations from ideality were calculated. Additionally, the Kirkwood's correlation factors (g _K ) were found. The values of these properties are discussed in terms of interactions of acetonitrile with butan-1-ol and butan-2-ol.     

On the molecular structure of the phytochrome chromophore: X-ray analysis of two 2,3-dihydrobilatriene-abc derivatives

The molecular and crystal structures of the two 2,3-dihydrobilatrienes-abc1 and2, representing model compounds for the phytochrome chromophore, were determined by X-ray crystallography at 97 K. Crystals of the racemate1 contain disordered regions. Both molecules are found to be ofall-(Z) configuration, assuming a helical conformation. The acidic hydrogen atoms are localized at the nitrogen atoms of rings A, C and D. A summary of the geometries of unsaturated five-membered rings as observed in four accurate low-temperature crystal structures of bilatrienes-abc is given.Herrn Prof.Josef Schurz zum 60. Geburtstag gewidmet.     

Determination of the Molecular Weight Distribution of Polyethylene Terephthalate by Gel Permeation Chromatography

Abstract

The determination of the molecular weight distribution of polyethylene terephthalate by GPC at room temperature is described. The solvent used is o-chlorophenol-chloroform (1:9) and pure chloroform is used as eluent. K and alpha of the Mark-Houwink equation of polyethylene terephthalate and of polystyrene in this solvent system were obtained. It was shown that the universal calibration can be applied.     

ESR study of the reaction of decacarbonyidimanganese with thallium(i) 3,6-di-tert-butyl-o-benzosendquinolate in solutions

The reaction of decacarbonyldimanganese Mu₂(CO)₁₀ (1) With thallium(t) 3,6-di-tert-butyl-o-benzosemiquinolate (2) in solution was studied by ESR spectroscopy. Irradiation of solutions containing1 and2 in organic solvents with visible light at 220–280 K leads totrinuclear MnTlMn complex (3). An analysis of hyperfine structure parameters indicates that3 is a semiquinone complex of thallium. A possible mechanism of the formation of complex3 and its molecular structure was discussed.Translated fromIzveshya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 95–98, January, 1996.     

Enantiodiscrimination of equol in β-cyclodextrin: an experimental and computational study

The interaction between the equol enantiomers and β -cyclodextrin is studied by molecular mechanics and molecular dynamics calculations. The chromatographic retention order is determined by these theoretical methods and compared with experimental findings. In the molecular mechanics calculations, the simultaneous relaxation of the host and the guest molecules is allowed, both in a vacuum and in aqueous solution. In the molecular dynamics calculations, the interaction energy between each enantiomer and the cavity is determined carrying out a simulation of 12 trajectories with different initial conditions at constant temperature (293 K), and minimising the energy of the structures extracted along the trajectories. To determine the preferential binding site and orientation of each guest molecule, the numerical density of presence in a volume element is calculated and compared with regions of maximum enantioselectivity. The more stable complex predicted in both cases is formed with R-equol, in agreement with experimental results.     

H-NMR Spectral and Dielectric Behaviours of the 2-Metoxyethanol-Tetrahydrofuran Solvent System

Abstract

Relative permittivities (E ₁₂) have been measured for 2-metoxyethanol (ME)-tetrahydrofuran (THF) binary liquid mixtures over the whole compositions range at various temperatures ranging from 291.15 K to 308.15 K. The experimental data were used to test some empirical equations of the type: y ₁₂ = y ₁₂(t) and y ₁₂ = y ₁₂ (X ₁) [where: y ₁₂-E ₁₂]. From all these data, the temperature coefficients of relative permittivities (α₁₂) and the excess extrathermodynamic parameters ε^E were calculated. The ¹H-NMR spectra of liquid binary mixtures of ME and THF, were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data the values of the values of the spectral structural parameters were found, δδ(ME-THF). These structural parameters as a function concentration suggest the formation of stable 3ME.THF types intermolecular complexes.     

Magnesium and calcium complexes with two diimine radical-anion ligands. Molecular structure of the Ca complex with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Four- and five-coordinate magnesium and calcium complexes containing two diimine radical-anion ligands with compositions (dpp-BIAN)₂Mg (1), (dpp-BIAN)₂Ca (2), (dtb-BIAN)₂Mg (3), and (dtb-BIAN)₂Ca(THF) (4) (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene and dtb-BIAN is 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were synthesized. At 120 K, the ESR spectra of complexes 1–4 in a toluene matrix show signals characteristic of biradical derivatives. The molecular structure of compound 2 was established by X-ray diffraction analysis. At 293 K, the magnetic moments of compounds 1, 2, 3, and 4 are 2.55, 2.57, 2.76, and 2.79 μ_B, respectively, which are indicative of the presence of two unpaired electrons localized on the ligands.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2051–2055, October, 2004.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  

Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials.     

The effect of molecular polarity on nem/catic phase stability in 12-vertex carboranes

Weakly polar–polar isosteric pairs of 12-vertex p-carborane [closo-1,12-C₂B₁₀H₁₂] (1[12]) and monocarbaborate [closo-1-CB₁₁H₁₂]^? (2[12]) nematic liquid crystals, in which the difference in the calculated molecular dipole moment is 11.3 D, were synthesised, and the effect of the dipole moment on nematic phase stability was investigated. The trend observed for the 12-vertex series ([12]) was identical to that of the previously investigated 10-vertex series ([10]) containing [closo-1,10-C₂B₈H₁₀] (1[10]) and [closo-1-CB₉H₁₀]^? (2[10]): the uniform increase in the molecular dipole moment in the pairs of mesogens does not correspond to a uniform change in the clearing temperature, T_NI. This demonstrates the role of a remote substituent in modulating the intermolecular dipole–dipole interactions. The magnitude of such interactions was calculated (using density functional theory methods) for a pair of polar (2[12]d–2[12]d) and an analogous pair of weakly polar (1[12]d–1[12]d) molecules. All results for the 12-vertex series ([12]) were analysed relative to the 10-vertex analogues ([10]).     

Diversity-oriented TsOH catalysis-enabled construction of tanshinone-substituted bis(indolyl/pyrrolyl)methanes and their biological evaluation for anticancer activities

We have developed an efficient and straightforward methodology for the synthesis of novel tanshinone-substituted bis(indolyl/pyrrolyl)methane scaffolds 3 through TsOH catalysis-enabled addition of indoles or pyrroles 1 with tanshinones 2 based on molecular hybridization strategy. Products were smoothly obtained in good yields (up to 81% yield). This protocol also represents the first construction of tanshinone skeleton-fused bis(indolyl/pyrrolyl)methane scaffolds, thus leading to new knowledge in the fields of both molecular complexity and diversity-oriented synthesis and the lead compound discovery. Furthermore, their biological activities against human leukemia cells K562, human prostate cancer cells PC-3, and human lung cancer cells A549 have been preliminarily demonstrated by in vitro assays. The results demonstrated that most of these compounds 3 obtained by this protocol showed comparable activity to the positive control of cisplatin.     

Structural Redetermination of Rh4(CO)12 at 293 and 173 K and Analysis of the Thermal Motion in Relation to the Dynamical Behavior

The structure of Rh₄(CO)₁₂ (1) has been redetermined at room temperature and at 173 K. Crystallographic data for 1 at 293 K are as follows: C₁₂O₁₂Rh₄, space group P2₁/c, a=9.209(3), b=11.790(7), c=17.721(8) Å, =90.46(3)°, V=1924.0(16) ų, Z=4, 5570 reflections to =30.0°, and R=0.030. For 1 at 173 K the data are as follows: space group P2₁/c, a=9.127(3), b=11.672(6), c=17.492(13) Å, =90.64(5)°, V=1863.3(18) ų, Z=4, 3782 reflections to =26.3°, and R=0.033. There was no detectable phase change on cooling to 173 K. Crystals of 1 are twinned by pseudo-merohedry, but a satisfactory refinement was obtained by assuming a (100) twinning mirror plane. TLS analysis of the anisotropic displacement parameters at both temperatures has been undertaken. Investigation of the mean square displacement difference between the observed and the rigid body displacement parameters reveals there is a signficant internal motion of the carbonyl ligands relative to the metal skeleton. This motion is consistent with a normal mode or modes of C ₃ symmetry.     

Studies on Associated Solutions. Part II. Physicochemical Properties of Acetonitrile-Propan-2-ol Mixtures

Abstract

The ¹H-NMR spectra of liquid binary mixtures of acetonitrile and propan-2-ol, were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data were found the values of the spectral parameter, Δδ(ACN-PrOH-2). The densities (d ₁₂) and relative permittivities (?₁₂) of the mixed solvent were measured at 288.15K, 293.15K, 298.15K, 303.15K and 308.15K, as well as refractive indices at 298.15K. From all these data, the molar volumes (V _m), temperature coefficients of relative permittivities (α_n) and their deviations from ideality were calculated. Additionally, the Kirkwood's correlation factors (g _K) were found. The values of these properties are discussed in terms of interactions of acetonitrile with propan-2-ol.     

α-Keggin tungstogermanate-supported transition metal complexes: hydrothermal synthesis,characterization, and magnetism of Cu2(phen)4(GeW12O40) and [Ni2(bpy)4(H2O)2(GeW12O40)]⋅2H2O

Two new α-Keggin polyoxometalates, [Cu₂(phen)₄(GeW₁₂O₄₀)] (1) and [Ni₂(bpy)₄(H₂O)₂(GeW₁₂O₄₀)]·2H₂O (2) (phen?=?1,10-phenanthroline, bpy?=?2,2′-bipyridine), have been hydrothermally synthesized and characterized by elemental analysis, IR, TG, single-crystal X-ray diffraction, and magnetic properties. Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, and 1 is assembled into two-dimensional (2-D) layers parallel to (1?0?1) based on the adjacent phen π···π stacking interactions (3.788(8)?Å). Variable temperature magnetic measurements show ferromagnetic behavior from 300 to 2?K. Compound 2 crystallizes in the triclinic system, space group P-1, and 2 is assembled into 2-D layers parallel to (1?0?1) based on the adjacent bpy π···π stacking interactions (3.07?Å). Variable temperature magnetic measurements show a weak ferromagnetic behavior from 300 to 26?K followed by antiferromagnetic behavior below 26?K.     

Thermal Decomposition and Glass Transition Temperature of Poly(methyl Methacrylate) and Poly(isobutyl Methacrylate)

Abstract

The thermal decomposition and the glass transition temperatures of poly(methyl methacrylate) (PMMA) and poly(isobutyl methacrylate) (PiBuMA) were studied with a differential scanning calorimeter (DSC). The undecomposed and decomposed polymers were analyzed by gel permeation chromatography (GPC) for molecular weight distributions and by DSC for changes in the thermal properties and glass transition temperatures, T. In the isothermal decomposition of PMMA and PiBuMA, depolymerization reactions exclusively are operative. During low temperature decompositions, longer PMMA chains depolymerize first. These are followed by the shorter chains. In the case of PiBuMA, the shorter chains depolymerize first. Some of these undergo chain recombinations to yield very high molecular weight products. For identical values of weight loss, the respective decomposition temperatures for PiBuMA are 40 to 70 K lower than those for PMMA. The activation energies of decomposition (42 kJ/mol for PMMA and 67 kJ/mol for PiBuMA) have been found to be lower than those reported in the literature. Although T_g∞ of PiBuMA (331 K) agrees well with the literature value (326 K), T_g∞ of atactic PMMA (394 K) is higher than the reported value (378 K).