排序方式: 共有42条查询结果,搜索用时 15 毫秒
1.
G. M. Mamardashvili R. S. Kumeev N. Zh. Mamardashvili 《Russian Journal of Inorganic Chemistry》2006,51(8):1264-1269
The formation of host-guest complexes between dimeric cyclophane zinc diphenylporphyrinates and bidentate ligands of different nature containing two nitrogen atoms has been studied by the spectrophotometric titration method and 1H NMR spectroscopy in a toluene-methanol (2: 1) binary solvent. The complexation of these dimeric porphyrinates with 1,4-diazabicyclo[2,2,2]octane or pyrazine can lead to 1: 1 or 1: 2 complexes, depending on the metalloporphyrin-to-ligand molar ratio. The stability constants of the porphyrinate-ligand complexes and concentration ranges of their formation have been determined. 相似文献
2.
Pukhovskaya S. G. Guseva L. Zh. Semeikin A. S. Kumeev R. S. Golubchikov O. A. 《Russian Journal of Coordination Chemistry》2003,29(11):805-809
Cobalt(II) and zinc(II) complexes with 5,15-di(o-methoxyphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra-n-buthylporphyrin and its capped analogues, where the MN4 reaction site is shielded by bridging groups containing m-phenylene and dimethoxy-substitutedp-phenylene fragments, were synthesized. Equilibrium constants of additional coordination of pyridine and N-methylimidazole by these metalloporphyrins were determined at 298 K. It was found that steric distortion of the porphyrin core destabilizes extra complexes. 相似文献
3.
N. M. Berezina Vu Thi Thao D. R. Karimov R. S. Kumeev A. V. Kustov M. I. Bazanov D. B. Berezin 《Russian Journal of General Chemistry》2014,84(4):737-744
Spectral properties and chemical stability of Mn(III), Mn(IV), Fe(III), Fe(IV), and Cu(III) complexes of β-octabromotriphenylcorrole [(β-Br)8(ms-Ph)3Cor], synthesized from β-unsubstituted compounds by their reaction with molecular bromine, were studied. Cyclic voltammetry, electron microscopy, and X-ray spectral microanalysis were used to obtain electrochemical characteristics of metal corroles M(β-Br)8(ms-Ph)3Cor and gain insight into the surface texture of active catalysts on the basis of metal corroles. The electron-acceptor β-bromine substitution in the MCor macrocycle shifts the equilibrium in electron-donor solvents to lower oxidation states of the metals and also stabilizes manganese and destabilizes copper complexes in the protondonor medium HOAc-H2SO4. The electrocatalytic activity of the complexes in the reduction of molecular oxygen depends on the nature of the ligand and increases in the order Mn ≤ Cu ? Fe in the case of β-octabrominated macrocycles. The character of distribution of active centers on the surface of the catalysts was established for the first time. 相似文献
4.
N. Sh. Lebedeva R. S. Kumeev G. A. Al’per E. V. Parfenyuk A. S. Vashurin T. V. Tararykina 《Journal of solution chemistry》2007,36(6):793-801
For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C6H4—OC11H23)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods.
It has been found that in o-xylene at concentrations of Zn(4—O—CO—C6H4—OC11H23)Pc higher than 6×10−4 mol⋅L−1
π–π dimers species are formed (λ
max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C6H4—OC11H23)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes.
Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C6H4—OC11H23)Pc—DABCO—Zn(4—O—CO—C6H4—OC11H23)Pc sandwich dimers (λ
max= 675 nm). 相似文献
5.
R. S. Kumeev M. Yu. Nikiforov E. D. Totchasov G. A. Al’per 《Journal of Structural Chemistry》2008,49(6):1120-1123
Chemical shifts (c.s.) of 1H nuclei in methanol are measured for methanol-benzene and methanol-phenanthrene systems. A method to determine the equilibrium constant of the molecular association reaction by NMR spectroscopy data is proposed for systems with low solubility of a compound when the dependence of c.s. on the composition is close to a straight line. The equilibrium constants for the formation of molecular complexes in methanol-benzene and methanol-phenanthrene systems are found. 相似文献
6.
I. V. Terekhova R. S. Kumeev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(1):1-6
Complex formation of α- and β-cyclodextrins with isoniazid, a antituberculous pharmaceutical, is studied using such methods
as calorimetry and 1H NMR at 298.15 K. On the basis of the obtained experimental data, it is shown that α- and β-cyclodextrins form 1 : 1 inclusion
complexes with isoniazid, which are characterized by low stability in aqueous solution. Along with this, deeper penetration
of isoniazid into the cavity of β-cyclodextrin, accompanied by more intensive dehydration of the reagents, is observed. The
results are interpreted in terms of influence of structure of reagents and their state in solution on the binding mode, driving
forces, and thermodynamic parameters of the complex formation. 相似文献
7.
Irina V. Terekhova Malgorzata Koźbiał Roman S. Kumeev Gennady A. Alper 《Journal of solution chemistry》2011,40(8):1435-1446
Inclusion complex formation of hydroxypropylated α-, β- and γ-cyclodextrins with riboflavin (vitamin B2) and alloxazine was studied by spectroscopic and solubility methods. Alloxazine, which is a structural analog of riboflavin,
was considered in order to evaluate the role of ribityl and methyl substituents in complexation. Thermodynamic parameters
for 1:1 complex formation were obtained and analyzed in terms of influence of the reagent structure on the binding process.
It was shown that the cavity of hydroxypropyl-β-cyclodextrin is more appropriate for formation of stable complexes. The complexes are enthalpy stabilized, due to prevalence
of van der Waals interactions and possible hydrogen bonding. The partial insertion of riboflavin into the cyclodextrin cavity
was revealed by 1H NMR and computer modeling. The ribityl side chain, which prevents deep inclusion, is located nearby the wider rim of the
cyclodextrin molecule and can undergo destruction. Penetration of the alloxazine molecule into the macrocyclic cavity is deeper
and accompanied by formation of more stable inclusion complexes. Hydroxypropyl-β-cyclodextrin was found to be the more efficient solubilizing agent for riboflavin and alloxazine, whereas a stabilization
action of cyclodextrins towards riboflavin was not observed. 相似文献
8.
D. F. Pyreu E. S. Alekseeva T. A. Simagina M. S. Gruzdev R. S. Kumeev S. N. Gridchin 《Russian Journal of Inorganic Chemistry》2018,63(2):180-190
The formation of mixed-ligand complexes in the M(II)–Nta and Ida–L systems (M = Co, Zn; L = His, Orn, Lys, Gly, Im, en), where Ida and Nta are the residues of iminodiacetic and nitrilotriacetic acids, was studied by pH-metry, calorimetry, and NMR spectroscopy. The thermodynamic parameters (logK, Δ r G0, Δ r H, Δ r S) of formation for these complexes were determined at 298.15 K and an ionic strength I = 0.5 (KNO3). The most probable pattern of coordination between a complexone and an amino acid in mixed-ligand complexes was revealed. 相似文献
9.
V. E. Petrenko M. L. Antipova D. L. Gurina E. G. Odintsova R. S. Kumeev V. A. Golubev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(7):1379-1384
Hydrogen-bonded complexes of acetylsalicylic acid with polar co-solvents in supercritical carbon dioxide, modified by methanol, ethanol, and acetone of 0.03 mole fraction concentration, are studied by numerical methods of classical molecular dynamics simulation and quantum chemical calculations. The structure, energy of formation, and lifetime of hydrogen-bonded complexes are determined, along with their temperature dependences (from 318 to 388 K at constant density of 0.7 g cm?3). It is shown that the hydrogen bonds between acetylsalicylic acid and methanol are most stable at 318 K and are characterized by the highest value of absolute energy. At higher supercritical temperatures, however, the longest lifetime is observed for acetylsalicylic acid–ethanol complexes. These results correlate with the known literature experimental data showing that the maximum solubility of acetylsalicylic acid at density values close to those considered in this work and at temperatures of 318 and 328 K is achieved when using methanol and ethanol as co-solvents, respectively. 相似文献
10.
Mamardashvili N. Zh. Surov O. V. Kumeev R. S. Storonkina O. E. Al'per G. A. 《Russian Journal of Organic Chemistry》2002,38(10):1485-1488
Four new unsymmetrically substituted porphyrins have been synthesized using 10-aryl-a,c-biladiene dihydrobromide as key intermediate. 相似文献