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101.
A novel direct, flexible, and robust approach to the iso-ergoline tetracyclic system in which a five or six-membered ring is established by intramolecular carbene C-H insertion is reported. The protocol involves a two step conversion of an aromatic aldehyde to the corresponding hydrazone and without purification further conversion to the diazo-compound followed by thermal carbene formation and C-H insertion α to a nitrogen. 相似文献
102.
Aliakbar Dehno Khalaji Karla Fejfarova Michal Dusek Debasis Das 《Monatshefte für Chemie / Chemical Monthly》2012,41(3):753-761
Abstract
2-Cyano-3-(2,5-dimethoxyphenyl)acrylic acid and its novel mononuclear square-planar copper(II) complex dipiperidinium tetrakis[2-cyano-3-(2,5-dimethoxyphenyl)acrylic acid]copper(II) ((Pip-H+)2[CuL4]2−) were synthesized and characterized by elemental analyses, FT–IR, UV–Vis spectroscopy, and thermogravimetric analysis. Moreover, the ligand was characterized by 1H and 13C NMR spectroscopy. The structures of the ligand and its copper(II) complex were confirmed by single-crystal X-ray crystallography. Whereas the ligand crystallizes in the triclinic space group Pī with unit cell parameters a = 4.6911(2) ?, b = 9.0181(4) ?, c = 13.7084(6) ?, α = 74.946(4)°, β = 87.152(4)°, γ = 89.220(4)°, V = 559.34(4) ?3, and Z = 2, the complex crystallizes in the orthorhombic space group Pccn with unit cell parameters a = 27.5486(5) ?, b = 12.9484(2) ?, c = 15.8822(3) ?, V = 5,665.34(17) ?3, and Z = 4. 相似文献103.
Karla Calfumán Paulina Dreyse Camilo García Maria J. Aguirre Tomás Beltrán Eva Guillamón Iván Sorribes Cristian Vicent Rosa Llusar Mauricio Isaacs 《Macromolecular Symposia》2011,304(1):93-100
Summary: This paper describes the electrochemical reduction of nitrite ion in 0.1 M NaClO4, on glassy carbon or ITO electrodes modified with mixtures PVC- tetraruthenated metalloporphyrins. This electrode is able to keep the extraordinary electrocatalytic properties of the macrocycle allowing multielectronic transfers and a great stability as a consequence of the inclusion of the macrocycles into a polymeric support such as PVC. On the other hand, the electrochemical reduction of nitrite ion on these modified electrodes studied by cyclic voltammetry shows an enhancement in the current values and lower overpotential compared with the activity of the bare glassy carbon electrode. Controlled potential electrolysis experiments verify the production of ammonia, hydrazine and hydroxylamine, showing the electrocatalytic character and the stability of this modified electrode. 相似文献
104.
Karla Patricia Salas-Martin 《Journal of organometallic chemistry》2010,695(23):2548-2556
Tricarbonyl-η5-pentadienylmanganese reacts with mercaptans RSH, R = Ph, C6F5, m-NH2C6H4, p-NH2C6H4, and HSCH2CH2 in the presence of ECH2CH2E, E = -PPh2 or -NH2 to give novel stable terminal thiolate mononuclear complexes fac-Mn(CO)3(SR)(Ph2PCH2CH2PPh2-κ2-P,P′) for R = Ph, C6F5, m-NH2C6H4, p-NH2C6H4, and HSCH2CH2 and fac-Mn(CO)3(SR)(H2NCH2CH2NH2-κ2-N,N′) for R = Ph and C6F5. Upon reaction of tricarbonyl-η5-pentadienylmanganese with ethylenediamine a dinuclear complex [fac-Mn(CO)3(μ-H2NCH2CH2NH-κ2-N,N′)]2 was formed wherein the diaminyl ligand functions in the capacity of chelating and bridging ligand. 相似文献
105.
Aliakbar Dehno Khalaji Karla Fejfarova Michal Dusek Alireza Najafi Chermahini 《Journal of chemical crystallography》2012,42(2):136-140
Abstract
Schiff-base compound 2-{[4-(Phenyldiazenyl)phenyl]iminomethyl}-5-bromo phenol (1), containing an azo group was synthesized from the reaction of p-aminoazobenzene with 5-bromosalicylaldehyde and characterized by elemental analyses, FT-IR spectroscopy and X-ray single-crystal diffraction analysis. Molecular orbital calculation has been carried out using density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the orthorhombic system, space group Pca21, with a = 12.1781(2) ?, b = 4.4894(10) ?, c = 27.7841(5) ?, V = 1519.02(5) ?3, and Z = 4. Compound 1 displays a trans configuration with respect to the C=N and N=N double bonds. 相似文献106.
Karla Rost 《Linear algebra and its applications》2012,436(10):3904-3918
Inverses of symmetric (or skewsymmetric) Toeplitz matrices as well as of centrosymmetric (or centro-skewsymmetric) Toeplitz-plus-Hankel matrices can be represented as sums of two split Bezoutians which are highly structured matrices since all of their rows and columns are symmetric or skewsymmetric vectors. Thus it is desirable to find matrix representations for split Bezoutians B. This is the main aim of the present paper.Recursion formulas for the entries of B are presented, bases of very simple split Bezoutians or of sparse matrices are constructed, and B is represented as a corresponding linear combination. Moreover, matrix representations of Gohberg/Semencul type are established. 相似文献
107.
Frequency‐Driven Self‐Organized Helical Superstructures Loaded with Mesogen‐Grafted Silica Nanoparticles
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Karla G. Gutierrez‐Cuevas Dr. Ling Wang Dr. Zhi‐gang Zheng Dr. Hari K. Bisoyi Prof. Guoqiang Li Dr. Loon‐Seng Tan Dr. Richard A. Vaia Prof. Quan Li 《Angewandte Chemie (International ed. in English)》2016,55(42):13090-13094
Adding colloidal nanoparticles into liquid‐crystal media has become a promising pathway either to enhance or to introduce novel properties for improved device performance. Here we designed and synthesized new colloidal hybrid silica nanoparticles passivated with a mesogenic monolayer on the surface to facilitate their organo‐solubility and compatibility in a liquid‐crystal host. The resulting nanoparticles were identified by 1H NMR spectroscopy, TEM, TGA, and UV/Vis techniques, and the hybrid nanoparticles were doped into a dual‐frequency cholesteric liquid‐crystal host to appraise both their compatibility with the host and the effect of the doping concentration on their electro‐optical properties. Interestingly, the silica‐nanoparticle‐doped liquid‐crystalline nanocomposites were found to be able to dynamically self‐organize into a helical configuration and exhibit multi‐stability, that is, homeotropic (transparent), focal conic (opaque), and planar states (partially transparent), depending on the frequency applied at sustained low voltage. Significantly, a higher contrast ratio between the transparent state and scattering state was accomplished in the nanoparticle‐embedded liquid‐crystal systems. 相似文献
108.
Sanhueza Luis Garrido Karla Celis Freddy García Macarena Cáceres Cesar Moczko Ewa Díaz Ramiro J. Aguirre María García Camilo 《Journal of Solid State Electrochemistry》2023,27(6):1511-1521
Journal of Solid State Electrochemistry - Screen-printed electrodes (SPEs) have the advantage of being considered electrochemical cells that can be implemented in portable sensor applications. With... 相似文献
109.
Marcos Pereira Estellita Lins Maria Karla Vervloet SolleroGuilherme Marques Calôba Angela Cristina Moreira da Silva 《European Journal of Operational Research》2007
Several DEA applications for benchmarking in utility regulation use classical models, which reveal inconsistencies due to Pareto inefficient targets. The natural course of action would be to incorporate weight restrictions, reflecting value judgments and requiring interaction between analyst and decision maker. We show that weight restricted DEA models still present some inconsistencies, since it is not possible to ensure that the target both dominates the observed DMU and lies on the empirical production frontier. 相似文献
110.
Jan Fbry Michal Duek Karla Fejfarov Radmila Krupkov Pemysl Vank Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):i49-i52
The structure of Rb2PO3F was determined at 290 and 130 K, while that of Cs2PO3F was determined at 240 and 100 K. Both compounds belong to the β‐K2SO4 family. The structure analysis did not reveal signs of a phase transition in either compound. Crystal chemical considerations do not favour the presence of a phase transition in either Rb2PO3F or Cs2PO3F. However, glass‐like phase transitions were observed by differential scanning calorimetry in slightly humid samples at 175 and 177 K for Rb2PO3F and Cs2PO3F, respectively, but were not observed in well dried samples. The bond distances are normal and Cs2PO3F is twinned. 相似文献