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1.
Formation of stable complexes between xenon and podand polyoxyethylene ligands was ascertained. The complexation process was studied by 129Xe NMR titration, NMR diffusiometry and heteronuclear NOE measurements. The ligands studied form a 1:1 complexes with Xe(0). Their stability constants depend on the ligand structure, i.e., polyoxyethylene chain length, number of complexating polyether units and the topology of the anchoring centre. 相似文献
2.
Jan Tengler Iva Kapustíková Ondřej Stropnický Petr Mokrý Michal Oravec Jozef Csöllei Josef Jampílek 《Central European Journal of Chemistry》2013,11(11):1757-1767
Eight hydrochlorides of 3-{2-[(2/4-fluorophenoxy)-ethylamino]}-2-hydroxypropyl-4-alkoxybenzoates and four hydrochlorides of 3-tert-butylamino-2-hydroxypropyl-4-butoxybenzoates were prepared as potential antagonists of the β1-adrenergic receptor (beta-blockers). A multistep synthesis of these compounds is described as well as their detailed analytical characterization. The pharmacokinetic properties of these weak base compounds are significantly influenced by their acid-base dissociation constant, pK a. The knowledge of this value is crucial for new drug development. This paper is aimed at developing a methodology that utilizes pH-dependent 1H NMR spectroscopy for its routine analysis. The selected predicted physico-chemical parameters of the new (arylcarbonyloxy)aminopropanols (i.e., aryloxyaminopropanol derivatives) were compared with the model drugs esmolol and flestolol. 相似文献
3.
Nuša Hojnik Matjaž Kristl Amalija Golobič Zvonko Jagličić Miha Drofenik 《Central European Journal of Chemistry》2014,12(2):220-226
This article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln2[(C5H4NCOO)6(H2O)4] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln3+ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid. 相似文献
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The velocity cross correlation integrals $$D_{{\text{ab}}}^{\text{J}} = (N/3)\mathop \smallint \limits_{\text{o}}^\infty< {\text{v}}_{{\text{1a}}} ({\text{t}}) \cdot {\text{v}}_{{\text{2b}}} (0) > {\text{dt,}} {\text{a}} {\text{ = }} {\text{1,2;}} {\text{b}} {\text{ = }} {\text{1,2}}$$ can be estimated from the intradiffusion coefficients D 1 ° and D 2 ° at each mole fraction x1 of component 1 on the basis of the exact relations among the Onsager phenomenological coefficients together with an assumed equation relating the joint diffusion coefficients D ab J . The results from several such equations are compared with experimental data and with similar results derived by Hertz in a different way to represent the behavior of f ab ≡D ab J x b in ideal reference systems. In some cases the agreement with experimental data for relatively ideal systems is even better than given by Hertz's results. For greater accuracy in predicting the D ab J from D a dg data one would need a prediction of the limiting value of D aa J at xa=0 for a=1,2. Presently known theory does not give a basis for estimating this limit reliably. 相似文献
6.
Gustavo D. de Souza M?nica A. Rodrigues Lucianno E. Fernandes Priscila P. Silva Reinaldo Ruggiero Elene C. Pereira-Maia Wendell Guerra 《Central European Journal of Chemistry》2013,11(2):290-294
New complexes of platinum and palladium were isolated with 4-nitrobenzoic hydrazide (4-NH) and characterized by spectroscopic techniques. Results show that the ligand is coordinated to metallic ions by the basic nitrogen of NH2 group and have the general structure cis-[M(4-NH)2X2] where M= Pt or Pd and x = Cl or I. The compound III, [Pt(4-NH)2I2], was found to display cytotoxicity (IC50 = 0.96 μmol L?1) against the K562 tumoral cell line. This complex is significantly more cytotoxic than cisplatin. 相似文献
7.
Vitor H. Rodrigues Maria M. R. R. Costa Etelvina M. Gomes Dmitry Isakov Michael S. Belsley 《Central European Journal of Chemistry》2014,12(10):1016-1022
The crystal structure and non-linear optical properties of L-alaninium perrhenate, C3H8NO2+ ReO4 ?, are reported. The protonated amino acid and the perrhenate anion have their usual geometries. The three-dimensional hydrogen-bonded network can be seen as a stacking of layers parallel to the (100) planes. Each layer is formed by chains of alternating positive and negative ions along the b and c axes. Hydrogen bonding of adjacent layers forms alternating chains along the a axis. A high damage threshold and a second-harmonic generation efficiency three times that of KDP make this new material potentially useful in non-linear optics. 相似文献
8.
Rǎdiţa Aparaschivei Valeriu Şunel Mihaela Holban Marcel Popa Jacques Desbrieres 《Central European Journal of Chemistry》2013,11(11):1808-1815
New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, 1H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening. 相似文献
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Alžbeta Takáčová Miroslava Smolinská Jozef Ryba Tomáš Mackuľak Jana Jokrllová Pavol Hronec Gabriel Čík 《Central European Journal of Chemistry》2014,12(11):1133-1143
In this work for disposal of the biologically hard decomposed pollutant Benzo[a]Pyrene (BaP) photooxidation Chlorella kessleri was used. The simulation model system under the different experimental conditions (varying biomass and light intensity) was evaluated. For quantitative analysis of the decrease in BaP, GC/MS technique was used. The highest degradation efficiency was achieved in the case of biomass from the culture of live algae (29%) and light intensity at level of 13.5 W m?2. When the dry biomass was used, degradation under the same conditions was lower because of lack of enzymatic activity in the system. 相似文献
10.
Luis H. Mendoza-Huizar Clara H. Rios-Reyes 《Central European Journal of Chemistry》2013,11(8):1381-1392
In the present work, the cobalt electrodeposition onto polycrystalline gold electrodes from aqueous solutions containing 0.01M CoSO4 + 1 M (NH4)2SO4 at pH=7 was analyzed. Linear voltammetry results suggested a change in the kinetic of the cobalt electrodeposition. In all cases, the nucleation rate (A), the number of active nucleation sites (N 0) and the saturation number of nuclei (N s ) values were potential dependent. The calculated Gibbs free energy (ΔG) for this system was 1.88×10?20 J nuclei?1 and the transfer coefficient for the Hydrogen Electroreduction Reaction (HER) was 0.47. 相似文献
11.
Agnieszka Nosal-Wiercińska 《Central European Journal of Chemistry》2014,12(2):213-219
The results of the kinetic measurements of Bi(III) electroreduction on a mercury electrode in 1–8 mol dm?3 chlorate (VII) solutions and in the presence of cystine demonstrate a dependence of the process on the temperature. The applied electrochemical techniques (DC polarography, cyclic and SWV voltammetry) allowed for the determination of the kinetic and thermodynamic parameters and their correlation with water activity. The catalytic activity of cystine was confirmed by the decrease in overall enthalpies of activation. The changes in the values of ΔH ≠ and ΔS 0 for Bi(III) electroreduction in the presence of cystine with the increase of chlorate (VII) concentration showed that the mechanism is different in solutions with low water activity as compared to those with high water activity. Probably it is connected with a different structure of the activated complexes (Bi-Hg(SR)2), mediating electron transfer. 相似文献
12.
Attila Sipos Antal Udvardy Attila C. Bényei Sándor Berényi 《Central European Journal of Chemistry》2013,11(8):1278-1285
The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields. 相似文献
13.
Here we report the transformation of tetracyclic morphinan salutaridine (1) into 2,3,10,11-tetrasubstituted (R)-aporphines. This method serves as another chemical proof of the previously verified biosynthetic connection with pentacyclic morphinan-6,8-diene-type thebaine. In the presence of nucleophiles, this procedure could lead to pharmacologically interesting new tetrasubstituted aporphinoids. The enantioselective synthesis of 7S-salutaridinol (2) has been also achieved in order to investigate the acid-catalyzed reactions of this natural morphinan. 相似文献
14.
Joana T. Zaharieva Maria Milanova Dimitar Todorovsky 《Central European Journal of Chemistry》2012,10(6):1907-1912
The paper considers the possibilities for mechanochemical synthesis of rare earth complexes. The complex Eu(TTA)3·phen (HTTA — 2-thenoyltrifluoroacetone, phen — 1,10-phenanthroline) is synthesized by mechanical treatment of a mixture of EuCl3.6H2O, HTTA, phen and NaOH in planetary ball mill Pulverisette 7 for 30 min at 800 min?1. The non reacted starting reagents and reaction side products are separated by treating activated mixture with water-ethanol solution following a procedure proposed in the literature. The elemental composition, X-ray diffraction pattern, IR spectra, optical properties (excitation and emission spectra, luminescence lifetime) and morphology of the mechanochemically synthesized complex are compared with those of the complex prepared from solution by the conventional method. The results confirm close similarity in the molecular structure and identity of the elemental composition, X-ray diffractograms and fluorescence properties of the compounds prepared by both methods. 相似文献
15.
The finite set of rate equations C m,n ' =α n,n-1 C m,n-1 (t)+α n,n C m,n (t)+α n,n+1 C m,n+1 (t), $$0 \leqslant m \leqslant N,0 \leqslant n \leqslant N,$$ where $$\alpha _{i,j}$$ are $\alpha _{j,j - 1} = A,\alpha _{j,j} = - \left( {A + B} \right),\alpha _{j,j + 1} = B$ , with $\alpha _{0,0} = - \alpha _{1,0} = - \alpha$ and $\alpha _{N,N} = - \alpha _{N - 1,N} = - b,\alpha _{0, - 1} = \alpha _{N,N + 1} = 0$ , subject to the initial condition $C_{m,n} \left( 0 \right) = \delta _{n,m}$ (Kronecker delta) for some $m$ , arises in a number of applications of mathematics and mathematical physics. We show that there are five sets of values of $a$ and $b$ for which the above system admits exact transient solutions. 相似文献
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Beata Kolesinska Agnieszka Mrozek Justyna Fraczyk Zbigniew J. Kaminski 《Central European Journal of Chemistry》2013,11(4):569-583
Tertiary phosphines in reaction with 2-chloro-4,6-dialkoxy-1,3,5-triazines gave unstable quaternary P-triazinylphosphonium chlorides, which readily decomposed with a departure of the alkyl group of the triazine ring substituent. Stable quaternary P-triazinylphosphonium chlorides were obtained only in reaction of 2-chloro-4,6-diphenoxy-1,3,5-triazine. Both, stable quaternary P-triazinylphosphonium chlorides as well unstable analogues prepared in situ activated carboxylic acid yielding “superactive” triazine esters, useful as highly efficient reagents in peptide bond synthesis. 相似文献
18.
Pawel Mierczynski Waldemar Maniukiewicz Tomasz P. Maniecki 《Central European Journal of Chemistry》2013,11(6):912-919
The activity of monometallic Pd, Ru, Ni and Cu catalysts supported on spinel ZnAl2O4 for water gas shift reaction (WGS) was investigated. The physicochemical properties of each catalyst was studied by XRD, TPR, BET and chemisorption methods. The highest activity was obtained for Cu/ZnAl2O4 among the catalysts tested. The activation process carried out in a reducing atmosphere 5%H2-95%Ar in the case of Cu/ZnAl2O4 system lead to the catalytic activity improvement. In the case of copper catalysts, the water gas shift reaction proceeded by the redox surface mechanism between Cu0/Cu+. The PdZn alloy formation after reduction at 350°C was shown. 相似文献
19.
Ekaterina V. Matveeva Elena V. Sharova Alexander N. Turanov Vasilii K. Karandashev Irina L. Odinets 《Central European Journal of Chemistry》2012,10(6):1933-1941
The investigation of the extraction properties of a series of polyoligodentate β-aminophosphine oxides 1–8 bearing from one to six phosphine oxide groups in a molecule towards Ln(III) and alkaline earth metals ions from neutral media has revealed that, using common diluents, the extraction efficiency increases with an increase of a number of P=O functions in a ligand. The addition of ionic liquid, namely 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([bmim][NTf2]), significantly increasing the extraction efficiency and application of IL concentration of 0.05 M (in 1,2-dichloroethane) providing the maximum recovery of metal ions with Lu/La separation factor reaching up to 91. Hexapodal tris[bis(2-diphenylphosphorylethyl)aminoethyl]amine 8 demonstrates the highest extraction under all conditions applied and the separation factor for U and Eu of this compound exceeded 103. 相似文献
20.
Pakiza Begum Debajyoti Bhattacharjee Bhupesh Kr. Mishra Ramesh C. Deka 《Theoretical chemistry accounts》2014,133(1):1-11
The density functional theory (DFT) calculations within the framework of generalized gradient approximation have been employed to systematically investigate the geometrical structures, stabilities, and electronic properties of Pd n Si q (n = 1–7 and q = 0, +1, ?1) clusters and compared them with the pure ${\text{Pd}}_{n + 1}^{q}$ (n = 1–7 and q = 0, +1, ?1) clusters for illustrating the effect of doping Si atom into palladium nanoclusters. The most stable configurations adopt a three-dimensional structure for both pure and Si-doped palladium clusters at n = 3–7. As a result of doping, the Pd n Si clusters adopt different geometries as compared to that of Pd n+1. A careful analysis of the binding energies per atom, fragmentation energies, second-order difference of energies, and HOMO–LUMO energy gaps as a function of cluster size shows that the clusters ${\text{Pd}}_{4}^{ + }$ , ${\text{Pd}}_{4}$ , ${\text{Pd}}_{8}^{ - }$ , ${\text{Pd}}_{5} {\text{Si}}^{0, + , - }$ , and ${\text{Pd}}_{7} {\text{Si}}^{0, + , - }$ possess relatively higher stability. There is enhancement in the stabilities of palladium frameworks due to doping with an impurity atom. In addition, the charge transfer has been analyzed to understand the effect of doped atom and compared further. 相似文献