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1.
A systematic study of the mesomorphic properties of three series of copper(II) complexes based on β-diketonate ligands containing branched side chains is reported. These disc-like compounds have four, six and eight flexible alkoxy side chains appended to the central core, in which two or four side chains were substituted by bulkier secondary alkoxy groups: 1-methylbutyloxy R ' = C5(2°) or 1-methylheptyloxy R ' = C8(2°). The mesomorphic results indicated that at least eight side chains are required to form stable columnar mesophases; other compounds with four or six side chains are not mesogenic regardless of the combination of the carbon length on the alkoxy or secondary alkoxy groups of the side chains. The compounds 3 with shorter R ' = C5(2°) side chains were all non-mesogenic regardless of the carbon length of three alkoxy side chains (R = C8, C10, C12) used. However, when the longer 1-methylheptyloxy side chain R ' = C8(2°) was substituted, the compounds 3b-3e with various alkoxy groups (R = C6, C7, C8, C10, C12) exhibited columnar phases. The mesophases were characterized and identified as columnar hexagonal phases (Colh), as expected, by thermal analysis and optical polarized microscopy. The presence of the introduced secondary alkoxy groups apparently appeared to influence the formation of columnar phases. The clearing points were relatively lower than other similar copper(II) compounds not substituted by secondary alkoxy side chains. 相似文献
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Summary The thermodynamic stepwise formation constants (log
T
K
n) of nine tervalent lanthanons (La3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Er3+ and Lu3+) with three fluorinated -ketoesters (methyltrifluroacetoacetate, ethyltrifluoroacetoacetate, and ethylpentafluoropropionylacetate) have been evaluated potentiometrically in a 50% dioxane-water mixture at 25 and 35 ± 0.01 °C. The values of log
T
K
n do not follow a linearity when plotted againstZ/r and invariably obey the sequence: La3+ < Nd3+ < Pr3+ < Sm3+ < Gd3+ < Eu3+ < Dy3+ Er3+ Lu3+ in all instances. The standard thermodynamic parameters (G
1
0
, H
1
0
, S
1
0
) associated with log
T
K
n have also been calculated. The validity of the chosen equilibrium model was examined by an error analysis usingS
min values (sum of the squared residuals), scatter plots, and slopes and intercepts of Abrahams-Kave type normal probability plots.
Komplexbildungsgleichgewichte von dreiwertigen Lanthanoiden mit fluorierten -Ketoestern in wäßrigem Dioxanmedium
Zusammenfassung Es wurden die thermodynamischen stufenweisen Komplexbildungskonstanten (log T K n) von 9 dreiwertigen Lanthanoiden (La3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Er3+ und Lu3+) mit drei fluorierten -Ketoestern (Methyltrifluoracetoacetat, Ethyltrifluoracetoacetat und Ethylpentafluopropionylacetat) in 50% Dioxan-Wasser bei 25 und 35±0.01 °C potentiometrisch bestimmt. Die Werte für log T K n ergeben keine lineare Abhängigkeit gegenüberZ/r, sie gehorchen stets der Reihenfolge: La3+ < Nd3+ < Pr3+ < Sm3+ < Gd3+ < Eu3+ < Dy3+ Er3+ Lu3+. Die thermodynamischen Standardparameter G 1 0 , H 1 0 und S 1 0 wurden ebenfalls berechnet. Die Gültigkeit des gewählten Gleichgewichtsmodells wurde unter Verwendung der Summe der Quadratreste (S min), von Streukurven und Steigung/Ordinatenabschnitt der Normalwahrscheinlichkeitsdarstellung nach Abrahams-Kave untersucht.相似文献
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SONG Le-Xin MENG Qing-Jin YOU Xiao-ZengCoordination Chemistry State Key Laboratory Coordination Chemistry Institute Nanjing University Nanjing Jiangsu China 《中国化学》1995,13(4):311-317
The supramolecular inclusion compound of β-cyclodextrin (β-CD, host) with (η5-cyclopentadienyl)tricarbonylmanganese [MnCp(CO)3, guest] was obtained in a crystalline state. The host-guest compound is thermally stable and do not liberate the guest on heating at 100$ in vacuum. It was characteried by elemental analysis,1H NMR, differential scanning thermal (DSC) analysis and TLC. Continueous variation plot by NMR method shows that β-CD formed 1:1 inclusion compound with MnCp(CO)3. On the basis of 1H NMR spectra and the model building with Corey Pauling Koltum (CPK) models, the most probable inclusion mode is proposed. 相似文献
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Long Chen Peng Wang Yanmo Chen Yu Zhang Meifang Zhu 《Frontiers of Chemistry in China》2008,3(4):445-450
In this paper, the crystallization behavior, thermal degradation properties, rheological behavior and the spinnability of
poly(β-hydroxybutyrate-co-hydroxyvalerate) (PHBV) fiber were studied. Experimental results indicated that the spherulite growth rate of PHBV was very
slow and its size was very large. PHBV began to degrade above 170°C. The flowing curve indicated that the processing temperature
and the residential time had important effects on PHBV melts. When the equipment of melting spinning was improved and processing
conditions were strictly controlled, the mechanical properties of the PHBV filament can comply with the requirements of the
American Pharmacopoeia.
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Translated from Journal of Donghua University (Natural Science Edition), 2007, 33(4): 425–430 相似文献
7.
In this paper an ideal model for the formation and development of the Qinghai-Xizang Plateau vortex is presented by a large number of statistical data and typical case studies. It points out that the Plateau vortex is shallow and thermal originated from a strong heat source near the surface of the west of the Plateau. Then moving eastward , it develops and becomes stronger and thicker with larger upward vertical velocity, and causes great precipitation in the middle Plateau. But at this time the heat source in the vortex becomes weaker, and even the heat sink occurs near the surface. Consequently, it disappears in a cold trough with a strong heat sink in the east of the Plateau. The heat source (sink) is mainly determined by the vertical eddy flux convergence (divergence) of the sensible heat caused by the cumulus convection and turbu-lance. Both the nonuniform heating (cooling) at the surface and the convergence (divergence) of the eddy kinetic energy coact and play an important role in the genesis (di 相似文献
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Yan Ling ZHANG Wei Sheng LIU Yang LI Xue Yi MA* Yao Zu CHEN National Laboratory of Applied Organic Chemistry Department of Chemistry Lanzhou University Lanzhou Department of Chemistry Zhejiang University Hangzhou 《中国化学快报》2001,(4)
The importance of Vitamin A for human health has been stressed in resent studies1, meanwhile its derivative so-called retinoic acid (RA) has been widely used as pharmaceutical to treat several types of skin disease and cancer2,3. However the application of retinoic acid is restrained for its poor water solubility, unstability and side effect on the human body.Cyclodextrins (CDs) are macrocyclic oligosaccharides built up from 6, 7, or 8 glucopyranose units called (, (, and (-CD, respectively… 相似文献
9.
Dongyu Zhao Kaijun Liao Xueyi Ma Xiaohua Yan 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(3-4):259-264
An inclusion complex of -cyclodextrin with andrographolide (Andro) was prepared by using a convenient new method of microwave irradiation. The structure of the inclusion complex was determined by UV and IR analyses as well as 1H NMR, 13C NMR and two dimensional NOE spectroscopic measurements. The results indicated that the possible stoichiometry of complex formation is 1:1 (guest:host ratio) and the two isomeric 1:1 inclusion complexes are present simultaneously in solution. Thermal studies proved the thermal stability of the inclusion complex. 相似文献
10.
Reactions of the lithium or sodium salt, [HC(CMeNDipp)2]M (Dipp = 2,6-diisopropylbenzene, M = Li or Na), with PBr3 or PCl3 affords a series of phosphenium cations that were characterized in the solid state by X-ray crystallography. Solid-state analysis reveals that for compounds 1 and 2, C–H activation of the ligand occurs and the phosphorus is bound to a nitrogen and carbon atom of the ligand. Compound 3 exhibits the more traditional nitrogen chelation of the ligand to the phosphorus atom. 相似文献
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Sulfonylisothiocyanates 1 and β,β-dimethylenamines 2 react to yield the dipoles 3. In nonpolar solvents an equilibrium exists between 3 and the thietanes 4. The free activation enthalpy for the ring closure 3→4 was obtained from the temperature dependent NMR spectra in liquid sulfur dioxide. Protonation of 3 with perchloric acid leads to the salts 8 which, as indicated by ΔG≠-values obtained from NMR spectra, are also capable of ring closure. 相似文献
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Mihly V. Pilipecz Tams R. Varga Zoltn Mucsi Pl Scheiber Pter Nemes 《Tetrahedron》2008,64(23):5545-5550
New indolizidines, quinolizidines, and octahydro-pyrido[1,2-a]azepines of lactam type were synthesized from 2-nitromethylene-pyrrolidine, -piperidine, and -hexahydroazepine, respectively, by [3+3] cyclizations with α,β-unsaturated carboxylic acid chlorides. In the case of quinolizidines, a double bond migration was observed, and explained in terms of amidity percentage. Cyanomethylene-pyrrolidine gave indolizidines of lactam type, while transformations of 1-cyanomethylene-tetrahydoisoquinoline resulted in lactams as well as ketones, when simple open-chain acid chlorides or cinnamoyl chloride were used, respectively. 相似文献
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A discharge-flow apparatus with resonance fluorescence and chemiluminescence detection has been used to monitor O2(b 1σ) production from several reactions of the HO2 radical at 300 K and 1-torr total pressure. O2(b), HO2, and OH were observed when F atoms were added to H2O2 in the gas phase. Signal strengths of O2(b) were proportional to initial concentrations of H2O2 and HO2. These observations were analyzed by using a simple three step mechanism and a more complete computer simulation with 22 reaction steps. The results indicate that the F + HO2 reaction yields O2(b) with an efficiency of (3.6 ± 1.4) × 10?3. By monitoring [O2(b)] and [HO2] upon addition of an excess second reactant to HO2, O2(b) yields from the reactions of HO2 with O, Cl, D, H, and OH were found to be <1 × 10?2, <5 × 10?4, <2 × 10?3, <8 × 10?3, and <1 × 10?3, respectively. Yields of O2(b) from the HO2 ± HO2 reaction were found to be less than 3 × 10?2. 相似文献
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Mitsuhiro Yoshimatsu Takashi Asahi Hiroshi Shimizu Tadashi Kataoka 《Heteroatom Chemistry》1995,6(3):259-264
Reactions of tris(methylsenleno)borane-SnCl4 with alkenes 1a–g gave α,β-bis(methylseleno)alkanes 2a –g, stereospecifically, and reactions with 1,3-dienes 1i–k afforded α,β-bis(methylseleno)alk-2-enes 2i–k , regioselectively. 相似文献
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