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121.
122.
Jesús Castro Paulo Prez Lourido Antonio Sousa‐Pedrares Elena Labisbal Maximiliano Carabel Jos Arturo García‐Vzquez 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):m65-m67
The title compound, [Cu(C4H8N2)4]SO4·0.5CH3CN·1.5H2O, consists of a double chain wherein the Cu centres are octahedrally coordinated by four 1‐methylimidazole ligands in the equatorial plane and by two axial sulfate ions which act as bridges between the Cu centres. The Cu—N bond lengths lie between 1.9929 (14) and 2.0226 (14) Å, but the Cu—O bond distances are longer, with values between 2.3496 (13) and 2.8276 (14) Å. The water molecules participate in the formation of a network of hydrogen bonds of significance in maintaining the connectivity of the structure. 相似文献
123.
Arturo Battaglia Andrea Guerrini Greta Varchi Ezio Bombardelli 《Tetrahedron letters》2006,47(16):2667-2670
Efficient syntheses of two taxol analogs bearing the linear polyamine spermine at 7- and 10-positions of paclitaxel and 10-deacetyl-paclitaxel have been developed. These polyamine-taxol-conjugates were isolated as water soluble difluoride salts. The aim of the present work was to introduce a chemical modification into taxol skeleton in order to increase drug selectivity toward tumor cells. The cytotoxic activity of these conjugates was evaluated in MCF7 and MCF7-R cell lines. The observed low cytotoxicity suggests that these conjugates could act as potential prodrugs. 相似文献
124.
Arturo Cert Pedro Delgado-Cobos Mariana Trujillo Prez-Lanzac 《Journal of mass spectrometry : JMS》1986,21(8):499-505
The mass spectra of imidazole-4(5)-carboxaldehyde, its two 1-methyl derivatives, 4(5)-nitroimidazole, 5(4)-nitroimidazole-4(5)-carboxaldehyde and 1-methyl-5-nitroimidazole-4-carboxaldehyde are presented and discussed in comparison with those of other imidazole-carboxaldehydes and nitroimidazoles earlier reported. The imidazole-carboxaldehydes and their 1-methyl derivatives exhibit the characteristic fragmentation of aromatic aldehydes, and differences between the isomers can be observed. The nitroimidazoles show the fragmentation typical of aromatic nitrocompounds. In the o-nitroimidazole-carboxaldehydes, the typical losses of aldehydes do not occur, but primary ortho effects between the formyl and nitro groups give rise to important fragmentation routes. In their 1-methyl derivatives, the presence of the methyl group adjacent to the nitro group originates additional double and secondary ortho effects. For some of these transformations, fragmentation mechanisms are proposed. 相似文献
125.
Caballero A Tormos R Espinosa A Velasco MD Tárraga A Miranda MA Molina P 《Organic letters》2004,6(24):4599-4602
A new 1-(9-anthryl)-4-ferrocenyl-2-aza-1,3-butadiene showing selective fluorescence enhancement upon binding to lithium cations over other alkaline cations in aqueous environment has been conveniently synthesized and characterized. [structure: see text] 相似文献
126.
Laura Fernández‐Llano M. Carmen Blanco‐López M. Jesús Lobo‐Castañón Arturo J. Miranda‐Ordieres Paulino Tuñón‐Blanco 《Electroanalysis》2007,19(15):1555-1561
A molecularly imprinted polymer for diclofenac (DCF) was prepared by thermal polymerization over silica beads using 2‐(dimethylamino)ethyl‐methacrylate as functional monomer. After silica elimination by HF treatment, the polymer was applied to the selective solid‐phase extraction of the drug from urine followed by its quantification by adsorptive differential pulse voltammetry. Results indicate that the drug could be selectively extracted from the sample and quantified at clinically relevant concentrations (μg/mL). 相似文献
127.
The decomposition of L2Ir(CO)R, R = n-alkyl) prepared in situ by the reacton of n-alkyllithium or -magnesium reagents with L2Ir(CO)Cl(2) produces a mixture of n-alkane and isomerized alkene, the ratio of which is strongly dependent on the concentration [L] of triphenylphosphine as well as certain other additives. When [L] = 0, positional isomerism and isotope scrabling are extensive as is the isomerism of added olefin, suggesting that β-hydride elimination is rapid and reversible and that any olefins participating in an iridium hydride addition-elimination sequence are also capable of exchange with free olefin in solution. When [Ph3P]/[2] >/ 1, the principal product (>90%) is the 1-alkene. No positional isomerism or isotope scrambling is observed only a minor amount of alkane is produced. A mechanistic scheme consistent these observations is proposed. 相似文献
128.
Luis E. Vilchız-Bravo Arturo Pacheco-Vega Brent E. Handy 《Journal of Thermal Analysis and Calorimetry》2013,111(1):857-867
We address the issue of hardware placement in the development of robust temperature control strategies that can be used to maintain a stable baseline during microcalorimetric experiments. The two different control loops, each defined by the location of sensor within the calorimeter that is used to achieve control, were first developed and then tested in a fully instrumented experimental system. Both control strategies were structured on proportional-integral-derivative controllers, after which calorimetric experiments were carried out to test the efficiency and robustness of the corresponding methodology. Results indicate that sensor placement plays a fundamental role in the controlled baseline stability and that is better to place the sensing device closer to the heater than to the central core. As part of this study, comparisons were also done against a previously reported control scheme based on heat-flow measurements. Results indicate that controlling only one variable, either temperature or heat flow is sufficient to compensate for heater-induced noise, but not for external fluctuations for which a combined strategy may be necessary. 相似文献
129.
Sirma Iglesias Dr. Arturo Gamonal Dr. Abasi Abudulimu Prof. Dr. Antonio Picón Dr. Esther Carrasco Prof. Dr. David Écija Dr. Cunming Liu Dr. Larry Luer Dr. Xiaoyi Zhang Dr. José Sánchez Costa Dr. Dooshaye Moonshiram 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10801-10810
Time-resolved X-ray (Tr-XAS) and optical transient absorption (OTA) spectroscopy on the pico-microsecond timescale coupled with density functional theory calculations are applied to study the light-induced spin crossover processes of a Fe-based macrocyclic complex in solution. Tr-XAS analysis after light illumination shows the formation of a seven-coordinated high-spin quintet metastable state, which relaxes to a six-coordinated high-spin configuration before decaying to the ground state. Kinetic analysis of the macrocyclic complex reveals an unprecedented long-lived decay lifetime of approximately 42.6 μs. Comparative studies with a non-macrocyclic counterpart illustrate a significantly shortened approximately 568-fold decay lifetime of about 75 ns, and highlight the importance of the ligand arrangement in stabilizing the reactivity of the excited state. Lastly, OTA analysis shows the seven-coordinated high-spin state to be formed within approximately 6.2 ps. These findings provide a complete understanding of the spin crossover reaction and relaxation pathways of the macrocyclic complex, and reveal the importance of a flexible coordination environment for their rational design. 相似文献
130.
Silvia Todros Chiara Venturato Arturo N. Natali Giuseppe Pace Vito Di Noto 《Journal of Polymer Science.Polymer Physics》2014,52(20):1337-1346
The effect of steam on the micro‐phase structure and mechanical properties of different block copolymers used in biomedical devices is investigated via FT‐IR, tensile tests and dynamic mechanical analysis (DMA). Steam sterilization, commonly performed on medical devices and simulated in this work, affects the copolymers' morphology, due to high temperature and humidity conditions. FT‐IR analysis reveals that steam induces a modification in the crystalline conformations of copolymers with a pre‐existing hydrogen bonding network, that is, thermoplastic polyurethanes (TPU) and poly(ether‐block‐amide) (PEBA), while it does not significantly affect the domain conformation in styrenic block copolymers (SEBS), due to weak interaction with water. As a consequence, relevant changes of the mechanical properties, closely related to the microdomain structure, are found for TPU and PEBA after sterilization, while SEBS mechanical behavior remains stable, as demonstrated by tensile tests and DMA results. For this reason, SEBS is suggested as the best choice in terms of durability in biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1337–1346 相似文献