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751.
Umberto Pichler Paolo Tecilla Umberto Tonellato Andrea Veronese 《Tetrahedron letters》2004,45(8):1643-1646
The Cu(II) complex of a ditopic macrocyclic ligand efficiently transports ω-amino acids of different length across a bulk chloroform membrane with promising selectivity. 相似文献
752.
[reaction: see text] The 2:1 inclusion complex between (2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) and 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TPPS(4)) behaves as a supramolecular sensitizer in water providing photooxygenation with turnover numbers up to 30,000 with a very minor sensitizer bleaching (<10%). The protocol, which employs only 4 equiv of the cyclodextrin additive with respect to the porphyrin sensitizer (5 x 10(-7) M), leads to high yield oxidation of model biomolecules such as l-methionine methyl ester and uracil and is also effective for phenol degradation in aqueous solution. 相似文献
753.
Pier Luigi Ferrarini Claudio Mori Oreste Livi Giuliana Biagi Anna Maria Marini 《Journal of heterocyclic chemistry》1983,20(4):1053-1057
The substituted 4H-pyrido[1, 2-a]pyrimidin-4-ones (I) were obtained by the condensation of substituted 2-aminopyridines with δ-ketocarboxylic esters in PPA. Some of the derivatives I were transformed into the corresponding 1, 8-naphthyridines II and III. 相似文献
754.
A. Marini G. Flor V. Massarotti V. Berbenni R. Riccardi 《Journal of Thermal Analysis and Calorimetry》1983,28(2):303-309
TG, DSC and X-ray measurements were made to characterize the water absorption process by Li (50%) — Na (50%)β-alumina. The equilibrium water content, dehydration enthalpies and lattice parameter values have been determined and compared with those previously obtained for pure Li and Naβ-aluminas. The mixedβ-alumina is shown to be very similar to Liβ-alumina as concerns the dehydration enthalpy and the temperature range in which the dehydration occurs, while it seems to be very similar to Naβ-alumina with respect to the equilibrium water content andc-axis values. 相似文献
755.
Antonio Da Settimo Giampaolo Primofiore Federico Da Settimo Gianluca Pardi Francesca Simorini Anna Maria Marini 《Journal of heterocyclic chemistry》2002,39(5):1007-1011
The synthetic potential of the title compounds benzimidazo[1,2‐a]quinazoline‐5(7H)‐one 2a and 5,7‐dihydro‐5‐oxopyrido[3′,2′:5,6]pyrimido[1,2‐a]benzimidazole 2b for the construction of novel polyhetero‐cyclic frameworks is reported. Compounds 2a,b , by conversion into their thio analogues 3a,b , were used for the synthesis of tetrazole ( 5a,b ) and triazole ( 7a,b ) derivatives, as well as for an unexpected synthesis of tri‐azoles 8a,b , isomers of 7a,b , resulting from the occurrence of a Dimroth rearrangement. 相似文献
756.
A. Marini V. Berbenni G. Bruni R. Riccardi M. Villa 《Journal of Thermal Analysis and Calorimetry》1997,50(1-2):137-144
The thermodynamics of β-cyclodextrin dehydration is investigated, by parallel DSC/TG experiments, on both fully and partially hydrated samples. The apparent dehydration enthalpies per mole of water are impossibly high and this fact suggests that another phenomenon, in addition to the rupture of the β-cyclodextrin/H2O hydrogen bonds, contributes to the peak area. All the experimental evidence agrees with an ‘interaction model’ which assumes that deydration is accompanied by a slow and reversible rearrangement of the β-cyclodextrin structure. 相似文献
757.
A comparison of the results obtained by applying three spectrophotometric methods (at fixed wavelength, second-derivative and multicomponent analysis) to the determination of gamma-oryzanol in rice bran oil is reported.At fixed wavelength the results are more accurate when using isopropyl alcohol, rather than n-heptane, to dilute the oil samples, because the absorption bands of gamma-oryzanol are red-shifted and the absorbance, measured at lambda(max)=327 nm, is less affected by the interference of the oil "matrix" (lambda(max)=314 nm in n-heptane).However, to obtain accurate results also in oils with a low content of gamma-oryzanol, it is necessary to perform the analysis using second-derivative ((2)D330.365) or multicomponent (lambda=310-360 nm) methods. The first one fully removes the interference of oil matrix whilst the second, which needs a specific computational program to process the spectrophotometric data, furnishes evidence the presence of some unexpected interference in the analysis and/or standards which are not representative of the analysed samples, from the square root of the sum of the squared differences at each point between the linear combination of the standards and the unknown spectra (RMS error).Finally, some aspects of the chemical, spectroscopic (UV, IR) and thermoanalytical (TG, DSC) behaviour of gamma-oryzanol and the values of the parameters which enable "computation" of its UV spectra are reported. 相似文献
758.
759.
Valentina Domenici Dr. Alberto Marini Carlo Alberto Veracini Prof. Jing Zhang Dr. Ronald Y. Dong Prof. 《Chemphyschem》2007,8(18):2575-2587
We present a theoretical and experimental 2H NMR study of the effect of external magnetic fields on the supramolecular organization of chiral smectic liquid‐crystalline mesophases, such as SmC* and re‐entrant SmC*. Three experimental cases in which the supramolecular helical structure of the smectic C* phase is unwound by a magnetic field (H), parallel to the helical axes of this phase, are discussed in detail. Unwinding of the helical structure is described by using a theoretical model based on the Landau‐de Gennes theory, which allows us to explain the transition temperatures among the SmA, SmC*, and uSmC* phases. The energy‐density behavior in the vicinity of the transitions and the value of the critical magnetic field HC for unwinding the helical structure are discussed by applying this model to three ferroelectric smectogens ( MBHB , 11EB1M7 , ZLL7/* ), which are studied by 2H NMR spectroscopy at different magnetic fields (from 2.4 to 9.4 Tesla). Furthermore, the tilt angle of the three smectogens in the SmC* phase has been directly evaluated, for the first time, by comparing the quadrupolar splittings at different magnetic fields. In one case, 2H NMR angular measurements are used to obtain the tilt angle in the re‐entrant smectic C phase. 相似文献
760.
Federico Marini Fabrizio Balestrieri Remo Bucci Antonio L. Magrì Domenico Marini 《Microchemical Journal》2003,74(3):239-248
Supervised pattern recognition appears to be a useful tool to authenticate foodstuffs according to their geographical or varietal origin, when a set of samples whose classification is known a priori are available. In this work, linear discriminant analysis and artificial neural networks trained by the back-propagation algorithm have been used to discriminate rice bran oils manufactured in three different countries (Italy, Thailand and Switzerland) according to their geographical origin. The variables to be included in the mathematical models have been chosen by means of Fisher F-ratio value among the chemical indices routinely determined on vegetable oils (particularly fatty acids, triglycerides and sterol composition). The prediction ability of all the classifiers was 100% as evaluated by cross-validation. 相似文献