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101.
Luis Escobar Eduardo C. Escudero‐Adn Pablo Ballester 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16251-16255
Planar pyridyl N‐oxides are encapsulated in mono‐metallic PdII/PtII‐cages based on a tetra‐pyridyl calix[4]pyrrole ligand. The exchange dynamics of the cage complexes are slow on both the NMR chemical shift and EXSY timescales, but encapsulation of the guests by the cages is fast on the human timescale. A “French doors” mechanism, involving the rotation of the meso‐phenyl walls of the cages, allows the passage of the planar guests. The encapsulation of quinuclidine N‐oxide, a sterically more demanding guest, is slower than pyridyl N‐oxides in the PdII‐cage, and does not take place in the PtII counterpart. A modification of the encapsulation mechanism for the quinuclidine N‐oxide is postulated that requires the partial dissociation of the PdII‐cage. The substrate binding selectivity featured by the cages is related to their different guest uptake/release mechanisms. 相似文献
102.
103.
Eduardo Corts Cortas Miryan Adaya Baos Olivia García‐Mellado De Corts 《Journal of heterocyclic chemistry》2004,41(2):277-280
A new synthesis to obtain eleven novel derivatives of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones with possible pharmacological activity in the central nervous system in two efficient steps has been developed. The final products were obtained by condensation and cyclization between 3‐[4‐chloro‐1,2‐phenylenediamine]‐5,5‐dimethyl‐2‐cyclohexenone with (o‐ m‐ and p‐substituted)benzaldehyde. The structure of all products was corroborated by ir, 1H‐nmr, 13C‐nmr and high resolution in ms. 相似文献
104.
Oliveira JS Sousa EH Basso LA Palaci M Dietze R Santos DS Moreira IS 《Chemical communications (Cambridge, England)》2004,(3):312-313
The in vitro kinetics of inactivation of both wild-type and I21V InhA enzymes by [FeII(CN)5(INH)]3- indicate that this process requires no activation by KatG, and no need for the presence of NADH. This inorganic complex may represent a new class of lead compounds to the development of anti-tubercular agents aiming at inhibition of a validated target. 相似文献
105.
Laura M. Bruno José L. de Lima Filho Eduardo H. de M. Melo Heizir F. de Castro 《Applied biochemistry and biotechnology》2004,113(1-3):189-199
Mucor miehei lipase was immobilized on magnetic polysiloxane-polyvinyl alcohol particles by covalent binding with high activity recovered.
The performance of the resulting immobilized biocatalyst was evaluated in the synthesis of flavor esters using heptane as
solvent. The impact on reaction rate was determined for enzyme concentration, molar ratio of the reactants, carbon chain length
of the reactants, and alcohol structure. Ester synthesis was maximized for substrates containing excess acyl donor and lipase
loading of 25 mg/mL. The biocatalyst selectivity for the carbon chain length was found to be different concerning the organic
acids and alcohols. High reaction rates were achieved for organic acids with 8 or 10 carbons, whereas increasing the alcohol
carbon chain length from 4 to 8 carbons gave much lower esterification yields. Optimal reaction rate was determined for the
synthesis of butyl caprylate (12 carbons). Esterification performance was also dependent on the alcohol structure, with maximum
activity occurring for primary alcohol. Secondary and tertiary alcohols decreased the reaction rates by more than 40%. 相似文献
106.
Eduardo H. Montoya Pablo A. Mendoza Patricia S. Bedregal Oscar R. Baltuano Isaac M. Cohen 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):175-178
A method that combines the use of non-destructive neutron activation analysis and high-resolution α spectrometry has been
developed for determination of the activities of 234U and 238U in geological samples of low uranium content. The 238U content is determined by k0-based neutron activation analysis, whereas the 234U/238U relationship is measured by α spectrometry after isolation and electrodeposition of the uranium extracted from a lixiviation
with 6 M HCl. The main advantage of the method is the simplicity of the chemical operations, including the fact that the steps
destined to assure similar chemical state for the tracer and the uranium species present in the sample are not necessary.
The method was applied to soil samples from sites of the North Peru Coast. Uranium concentration range 3–40 mg/kg and the
isotopic composition correspond to natural uranium, with about 10% uncertainty. 相似文献
107.
Francine F. Nachtigall Eduardo Ernesto Castellano Faruk Nome 《Supramolecular chemistry》2013,25(6):453-458
The interactions of calix[6]arene and p-tert-butylcalix[6]arene with aliphatic amines in acetonitrile solution were studied by spectrophotometric titrations in the UV region and 1H NMR spectrometry. Calix[6]arenes can undergo two deprotonations by aliphatic amines and the extent of the second proton transfer is mainly governed by the size of the α-substituent of the amine. 1H NMR spectra show that the macrocycle adopts a 1,2,3-alternate conformation and that the α-hydrogens of the ammonium ions are shielded by the π-clouds of the aromatic rings. The X-ray crystal structure of the dihexylammonium complex of the p-tert-butylcalix[6]arene dianion, reported here, confirms the 1,2,3-alternate conformation and shows one of the two ammonium moieties encapsulated in the inner cavity of the macrocycle. 相似文献
108.
109.
Hernández-Reyes CX Angeles-Beltrán D Lomas-Romero L González-Zamora E Gaviño R Cárdenas J Morales-Serna JA Negrón-Silva GE 《Molecules (Basel, Switzerland)》2012,17(3):3359-3369
New azanucleosides were obtained using sulphated zirconia (ZS) as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl) pyrimidine-2,4(1H,3H)-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl)-pyrimidine-2,4(1H,3H)-dione, with (S)-prolinol. The new templates were obtained with good yields following a route which exploits the reactivity of epoxides in the presence of sulphated zirconia as catalyst. The key step was carried out using microwave and solvent-free conditions and proceeds with high selectivity. 相似文献
110.
Madrigal-Santillán E Fragoso-Antonio S Valadez-Vega C Solano-Solano G Pérez CZ Sánchez-Gutiérrez M Izquierdo-Vega JA Gutiérrez-Salinas J Esquivel-Soto J Esquivel-Chirino C Sumaya-Martínez T Fregoso-Aguilar T Mendoza-Pérez J Morales-González JA 《Molecules (Basel, Switzerland)》2012,17(4):4435-4451
There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were organized as follows: a negative control group (without treatment), a positive group treated with B[a]P (200 mg/kg), a group administered with 800 mg/kg of CEE, and three groups treated with B[a]P and CEE (200, 400, and 800 mg/kg) respectively. The CEE and benzo[a]pyrene were administered orally for a week, on a daily basis. During this period the body weight, the feed intake, and the determination of antigenotoxic potential were quantified. At the end of this period, we continued with the same determinations for one week more (recovery period) but anymore administration of the substances. The animals treated with B[a]P showed a weight increase after the first week of administration. The same phenomenon was observed in the lots combined with B[a]P and CEE (low and medium doses). The dose of 800 mg/kg of CEE showed similar values to the control group at the end of the treatment period. In the second part of the assay, when the substances were not administered, these experimental groups regained their normal weight. The dose of CEE (800 mg/kg) was not genotoxic nor cytotoxic. On the contrary, the B[a]P increases the frequency of micronucleated normochromatic erythrocytes (MNNE) and reduces the rate of polychromatic erythrocytes (PE) at the end of the treatment period. With respect to the combined lots, a significant decrease in the MN rate was observed from the sixth to the eighth day of treatment with the two high doses applied; the highest protection (60%) was obtained with 800 mg/kg of CEE. The same dose showed an anticytotoxic effect which corresponded to an improvement of 62.5% in relation to the animals administered with the B[a]P. In the second period, all groups reached values that have been seen in the control group animals. Our results suggest that the inhibition of clastogenicity of the cranberry ethanolic extract against B[a]P is related to the antioxidant capacity of the combination of phytochemicals present in its chemical composition. 相似文献