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Raffaele P. Bonomo Vincenzo Cucinotta Franca D' Allessandro Giuseppe Impellizzeri Giuseppe Maccarrone Enrico Rizzarelli Graziella Vecchio 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(2):167-180
The functionalized cyclodextrin 6-deoxy-6-[1-(2-amino)ethylamino]--cyclodextrin was synthesized, and an NMR, EPR, pH-metric, and calorimetric investigation was carried out in aqueous solution in order to ascertain its behaviour towards protonation and copper(II) complex formation. The thermodynamic parameters of the ternary complex formation with alanine, phenylalanine and tryptophan enantiomeric pairs were also determined (25° C andI=0.1 mol dm–3). No thermodynamic enantioselectivity was observed in these systems, while a chiral, though poor, discrimination was observed in LEC: c.d. spectra also show enantiomeric stereoselectivity. The results of the present investigation, compared with previously reported results, suggest the occurence of acis-complex trans-complex equilibrium in such systems. 相似文献
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Karoly Vkey Jzsef Tams Arpd Somogyi Antonella Bertazzo Carlo Costa Graziella Allegri Roberta Seraglia Piero Traldi 《Journal of mass spectrometry : JMS》1992,27(11):1216-1219
Structural studies of a synthetic melanin, obtained by means of performic acid oxidation of tryptophan, were carried out by pyrolysis gas chromatography/mass Spectrometry (Py-GC/MS). To identify the best pyrolysis conditions, both Curie-point pyrolysis and filament pyrolysis were employed and the effects of pyrolysis temperatures and times were studied. Using the first approach, various compounds were identified: toluene, ethylbenzene, styrene, indole, methylindole, ethylindole, phenol, cresol and ethylphenol. Using filament pyrolysis some interesting differences could be observed. Whereas toluene, ethylbenzene, phenol, cresol and methylindole were found, neither indole nor ethylindole was detected. Instead, new pyrolysis products were evident, such as methylpyrrole and indolin-2-one. Hence filament pyrolysis seems to activate different thermal decomposition pathways of the melanin under study. It is suggested that tryptophan melanin is a polymer containing indole and hydroxyindole derivatives as subunits. 相似文献
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Graziella Tocco Michela Begala Giovanna Delogu Carmen Picciau Gianni Podda 《Tetrahedron letters》2004,45(37):6909-6913
In the presence of catalytic amount of indium(III) chloride (10 mol %), 2,2′-dihydroxybiphenyl and bis(2-hydroxyphenyl)methane react quickly, without using any solvent, with ketones or β-keto esters possessing at least one hydrogen atom in α to the ketone-carbonyl group, to afford some new dibenzo(d,f)(1,3)dioxepines and some 12H-dibenzo(d,g)(1,3)dioxocin derivatives, respectively. 相似文献
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Nishant Peddagopu Anna L. Pellegrino Carmela Bonaccorso Patrizia Rossi Paola Paoli Graziella Malandrino 《Molecules (Basel, Switzerland)》2022,27(19)
Very few sodium complexes are available as precursors for the syntheses of sodium-based nanostructured materials. Herein, the diglyme, triglyme, and tetraglyme (CH3O(CH2CH2O)nCH3, n = 2–4) adducts of sodium hexafluoroacetylacetonate were synthesized in a single-step reaction and characterized by IR spectroscopy, 1H, and 13C NMR. Single-crystal X-ray diffraction studies provide evidence of the formation of the ionic oligomeric structure [Na4(hfa)6]2−•2[Na(diglyme2]+ when the diglyme is coordinated, while a mononuclear seven-coordinated complex Na(hfa)•tetraglyme is formed with the tetraglyme. Reaction with the monoglyme (CH3OCH2CH2OCH3) does not occur, and the unadducted polymeric structure [Na(hfa)]n forms, while the triglyme gives rise to a liquid adduct, Na(hfa)•triglyme•H2O. Thermal analysis data reveal great potentialities for their applications as precursors in metalorganic chemical vapor deposition (MOCVD) and sol-gel processes. As a proof-of-concept, the Na(hfa)•tetraglyme adduct was successfully applied to both the low-pressure MOCVD and the sol-gel/spin-coating synthesis of NaF films. 相似文献
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In the current program for the preparation of an urban air map, this paper reports data obtained by the five base stations in the period 1997-2000 regarding traditional pollutants and gives the first results obtained in determining continuously benzene, toulene and PM10. Additional measurements have been carried out by a mobile station at the falcate zone, never tested before, which has very low traffic but with the presence of some small metal industries and, under favourable meteorological conditions, the effects of the harbour. A statistical study on the hourly-trend of particulate suspended matter in two zones of the city which have different traffic volume for the period 1995-1997 is also reported. The ozone characteristic peak at 15.00 is fully confirmed in all stations and over all the period contrarily to most Italian cities, which present the peak about three hours earlier. PM10 annual mean value during 1999 was a little higher than the legal one. Base stations "Archimede" and "Minissale" still present some risk of a stop or limitation of traffic even with respect to traditional or "new" pollutants. Statistical analysis of particulate suspended matter confirm the very different characteristics of the base stations under consideration. 相似文献
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Filippi A Roselli G Renzi G Grandinetti F Speranza M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(9):2072-2078
The kinetics and the stereochemistry of the protonation-induced unimolecular isomerization of (S)-(+)-1-D(1)-3-(p-tolyl)butane have been investigated in the gas phase in the 100-160 degrees C range. The process leads to the almost exclusive formation of the relevant meta isomer with complete racemization and partial 1,2-H shift in the migrating sec-butyl group. These results, together with the relevant activation parameters, point to the occurrence of low-energy, tightly bound isomeric sec-butyl cation/toluene complexes of defined structure and stability along the isomerization coordinate. The existence and the eta(1)-type structure of these low-energy intermediate species are confirmed by ab initio calculations on closely related systems at the MP2(full)/6-311++G**//HF/6-31+G** level of theory. Their role in the relevant energy surface clearly emerges from the comparison of the present results with those concerning sec-butylation of toluene carried out under comparable experimental conditions. 相似文献
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V. Cucinotta Alessandro Giuffrida Giulia Grasso Giuseppe Maccarrone Antonino Mazzaglia Graziella Vecchio 《Analytical and bioanalytical chemistry》2001,370(4):363-366
The separation of three pairs of enantiomeric herbicides has been successfully achieved by capillary electrophoresis at two different pH values in the presence of cyclodextrin derivatives previously synthesized in our laboratory. Two of these derivatives constitute a new class of receptor, the hemispherodextrins, in which a trehalose capping moiety is bonded to β-cyclodextrin. Because of their peculiar structure hemispherodextrins have very promising characteristics and the low receptor concentration required to achieve separation deserves particular interest. 相似文献