共查询到10条相似文献,搜索用时 78 毫秒
1.
The inclusion of vanadocene dichloride (VDC) and 1,1′-dimethyl vanadocene dichloride (MeVDC) into cyclodextrines (α-CD, β-CD
and γ-CD) was studied by EPR spectroscopy. It was found that VDC and MeVDC with β-CD and γ-CD form true inclusion compounds,
but with α-CD, VDC and MeVDC gave only fine dispersion mixtures. The inclusion was validated by anisotropic EPR spectra of
solid samples. In addition, the antimicrobial was validated by anisotropic EPR spectra of solid samples. In addition, the
antimicrobial behavior (against E. coli) of each of the complexes was determined. It was established that not only did VDC and MeVDC cause elongation of E. coli, but also the new vanadocene inclusion complexes were effective in this regard. 相似文献
2.
The results of kinetic and equilibrium experiments with the set of reaction of proton abstraction from 4-nitrophenyl[bis(ethylsulphonyl)]methane
in acetonitrile are reported. Two strong organic bases are used: 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene
(MTBD).
The rates of proton transfer reaction have been measured by T-jump method in the presence of perchlorate of the appropriate
base as a common cation BH+ and supporting electrolyte-tetrabutylammonium perchlorate (TBAP) in the temperature range between 20–40°C are: k
H
=1.32×107−2.00×107 and 2.82×107−4.84×107 dm 3mol−1s−1 for MTBD and TBD respectively. The enthalpies of activation ΔH
MTBD
≠
=13.5 and ΔH
TBD
≠
=18.1 kJmol−1. The entropies of activation are negative: ΔS
MTBD
≠
=−62.3 and ΔS
TBD
≠
=−40.3 Jmol−1K−1.
The change of the absorbance of the anion of 4-nitrophenyl[bis9ethylsulphonyl)]methane at the temperature 25°C in the presence
of common cation BH+ gives the equilibrium constants K=705 and 906 M−1 for MTBD and TBD respectively.
Kinetic and equilibrium results are discussed. The possible mechanism of proton transfer reaction between 4-nitrophenyl[bis(ethylsulphonyl)]methane
and cyclic organic bases: MTBD and TBD in acetonitrile is proposed. 相似文献
3.
Claudia Mureşanu Lucian Copolovici Florina Pogącean 《Central European Journal of Chemistry》2005,3(4):592-604
The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from
Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the
Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction:
in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots
of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed. 相似文献
4.
Twelve cardiac glycosides and aglycons were isolated from Strophanthus kombe seeds. Of these, eight were identified as cymarin, K-strophanthin-β, K-strophanthoside, periplocymarin, 17α-strophadogenin, erysimin (= helveticoside), erysimoside, and neoglucoerysimoside.
Four glycosides, preliminarily designated Sk-x, Sk-y, Sk-z, and Sk-20, were new. Their chemical structures were established
as 3β-O-β-D-glucopyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-glucoside), 3β-O-β-D-cymaropyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-cymaroside), 3β-O-β-D-cymaropyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β, 14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-strophanthotrioside), and 3-O-β-D-digitoxopyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β,14β, 19-trihydroxy-card-20(22)enolide (strophanthidol-3-O-gentiobiosyldigitoxoside), respectively.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 156–159, March–April, 2006. 相似文献
5.
N. N. Sidamonidze L. K. Janiashvili R. O. Vardiashvili R. A. Gakhokidze 《Chemistry of Natural Compounds》2006,42(2):127-128
A new synthesis of certain lactam-containing N-glycosides was developed. 2,3,4,6-Tetra-O-acetyl-β-D-gluco(galacto)pyranosylcaprolactams and 2,3,4,6-tetra-O-acetyl-β-D-gluco(galacto)pyranosylpyrrolidones were synthesized by condensation at room temperature of acetobromoglucose and acetobromogalactose
with ɛ-caprolactams and α-pyrrolidone.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 105–106, March–April, 2006. 相似文献
6.
R. P. Gorshkova V. V. Isakov V. A. Denisenko E. L. Nazarenko E. P. Ivanova L. S. Shevchenko 《Chemistry of Natural Compounds》2008,44(5):549-551
The O-specific polysaccharide of Alteromonas addita type strain KMM 3600T is constructed of trisaccharide repeat units containing L-rhamnose, D-glucose, and D-galactose. It
was established that the O-specific polysaccharide consists of trisaccharide repeat units with the structure →3)-α-D-Galp-(1→3)-α-L-Rhap-(1→3)-α-D-Glcp-(1→ based on monosaccharide analysis, Smith degradation, PMR and 13C NMR spectroscopy, and two-dimensional COSY, HSQC, and HMBC.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 445–447, September-October, 2008. 相似文献
7.
R. Bruce King 《Journal of mathematical chemistry》2008,44(1):5-19
The special projective linear groups PSL(2ℓ + 1) or L
2(2ℓ + 1) of order 2ℓ(2ℓ + 1)(ℓ + 1) can be used to study atomic shells of electrons with angular momentum quantum number ℓ
corresponding to the atomic p, d, f, and g shells for ℓ = 1, 2, 3, 4, respectively. For the atomic g shell the group L
2(9) is isomorphic with the alternating group A
6 on six objects of order 360 or the symmetry group of the 5-dimensional simplex, a 5-dimensional analogue of the tetrahedron
with 6 vertices and 15 edges. This leads to the subgroup chain SO(9) ⊃ SO(5) ⊃ L
2(9) for the atomic g shell analogous to the subgroup chain SO(7) ⊃ G
2 ⊃ L
2(7) ≈7
O for the atomic f shell. In the L
2(9) group only the representations of spherical harmonics or sums thereof, Γ(Yℓ), with dimensions dim Γ(Yℓ) or dim Γ(Yℓ) ± 1 divisible by 9 are found to be individually reducible to irreducible representations (irreps) or sums of irreps of L
2(9). This leads to term groupings such as S, PD, G, PF, DH, L, PK, DI, FH, M, FI, PO, DN, HK, R, etc., of increasing total
dimension for the irreps of SO(9) for various g
n
configurations in the atomic g shell. 相似文献
8.
Akram M. El-Didamony 《Central European Journal of Chemistry》2005,3(3):520-536
Three simple, accurate, and sensitive spectrophotometric methods (A, B and C) have been described for the indirect assay of
diltiazem hydrochloride (DIL.HCl), either in pure form or in pharmaceutical formulations. The first method (A) is based on
the oxidation of DIL.HCl by N-bromosuccinimide (NBS) and determination of unconsumed NBS by measuring the decrease in absorbance
of amaranth dye (AM) at a suitable λ
max
=521 nm. Other methods (B) and (C) involve the addition of excess cerric ammonium sulfate (CAS) and subsequent determination
of the unconsumed oxidant by a decrease in the red color of chromotrope 2R (C2R) at a suitable λ
max
=528 nm or a decrease in the orange-pink color of rhodamine 6G (Rh6G) at λ
max
=525 nm, respectively. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 3.0–9.0,
3.5–7.0 and 3.5–6.3 μg ml−1 for methods A, B and C, respectively. The apparent molar absorptivity, Sandell's sensitivity, detection and quantification
limits were calculated. The proposed methods have been applied successfully for the analysis of the drug in its pure form
and its dosage form. No interference was observed from a common pharmaceutical adjuvant. Statistical comparison of the results
with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. 相似文献
9.
Horia Petride Constantin Drãghici Cristina Florea Aurica Petride 《Central European Journal of Chemistry》2004,2(2):302-322
N-Benzylmorpholine,-piperidine, and-pyrrolidine (1A-C, resp.) are oxidised by RuO4 (generated in situ) at both endocyclic and exocyclic (benzylic) N—α-methylene positions to afford lactams (and dioxo-derivatives) and benzaldehyde (and benzoyl derivatives), respectively.
The N-oxides of 1A-C, formed by a minor side reaction, are not involved as intermediates. Control experiments showed the transient formation of
endo- and exocyclic iminium cations trapped with NaCN as the corresponding nitriles. The proposed course of the RuO4-mediated oxidation of 1A-C involves the consecutive steps 1⇒iminium cations+cyclic enamine⇒oxidation products. The endocyclic/exocyclic regioselectivity of the oxidation reaction lies
between 0.8 (for 1A) and 2.1 (for 1B). The amine cation radical and the N-α-C· carbon-centered radical seem not to be involved. 相似文献
10.
Yue Zhang Natsumi Watanabe Yuuko Miyawaki Yutaka Mune Kenta Fujii Yasuhiro Umebayashi Shin-ichi Ishiguro 《Journal of solution chemistry》2005,34(12):1429-1443
Aprotic N,N-dimethylpropionamide (DMPA) and N,N,N′,N′-tetramethylurea (TMU) are both strong donor solvents and coordinate to metal ions through the carbonyl oxygen atom. These
solvents show a different conformational aspect in the bulk phase, i.e., DMPA exists as either a planar cis or a nonplanar staggered conformer, while TMU exists in a single planar cis conformer. It has been established that the manganese(II) ion is solvated by five molecules in both solvents. Interestingly,
although the planar cis conformer of DMPA is more favorable than the nonplanar staggered one in the bulk phase, the reverse is the case in the coordination
sphere of the metal ion, i.e., a conformational change occurs upon solvation. To reveal the thermodynamic aspect of this conformational change, the complexation
of Mn(II) with bromide ions in DMPA and TMU has been studied by titration calorimetry at 298 K. It was found that the Mn(II)
ion forms mono-, di- and tri-bromo complexes in both solvents, and their formation constants, enthalpies and entropies were
obtained. The Δ H∘1 value for MnBr+ strongly depends on the solvent, i.e., it is positive (19.4 kJ-mol−1) in DMPA and negative (−8.7 kJ-mol−1) in TMU, whereas the Δ H^∘2 and Δ H∘3 values for the stepwise formation of MnBr2 and MnBr3− are both small and negative. The enthalpy of transfer ΔtH∘ from DMPA to TMU, which is evaluated on the basis of the extrathermodynamic TATB assumption, is 25.5 kJ-mol−1 for Mn2+ and −3.6 kJ-mol−1 for MnBr+. These values indicate that the difference between the formation enthalpy of MnBr+ in the two solvents, Δ H^∘1 (DMPA) – Δ H∘1 (TMU), is mainly ascribed to the value of ΔtH∘(Mn2+). It is found that the metal ion is also five-coordinated in the monobromo complex, MnBr(DMPA)4+ . The enthalpy for the conformational change of DMPA from its planar cis to the nonplanar staggered form is evaluated to be −11 and −5.5 kJ-mol−1 for Mn(DMPA)52 + and MnBr(DMPA)4+, respectively. Note that these values are significantly smaller than the corresponding value (5.0 kJ-mol−1) in the bulk phase. We thus conclude that, although steric hindrance among solvent molecules is reduced by replacing one
DMPA of Mn(DMPA)52 + with the relatively small bromide ion, DMPA molecules are still sterically hindered in the MnBr(DMPA)4+ complex. 相似文献