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Gianluca Nasini Lucio Merlini Giovanni Dario Andreetti Gabriele Bocelli Paolo Sgarabotto 《Tetrahedron》1982,38(18):2787-2796
The absolute configuration of the asymmetric carbons and the axial chirality of the natural mold metabolite cercosporin (from .) have been established on the basis of X-ray analysis and chemical reactions. The results confirm the inherent dissymmetry of the perylenequinone ring, the twisting of which gives rise to the diastereoisomer isocercosporin. The energy barrier for the conversion of cercosporin into isocercosporin has been evaluated. 相似文献
15.
Kinga Suwińska Marek Pietraszkicwicz Janusz Lipkowski Janusz Jurczak Giovanni. D Andreetti Gabriele Bocelli 《Journal of Molecular Structure》1981,75(1):121-127
The chiral crown ether was prepared according to the method described in the literature and its complex with potassium iodide was obtained. The crystal data are as follows: a = 10.315(4), b = 9.265(4), c = 15.88(2) Å, β = 100.70(7)°. V = 1494 Å,3 Z = 2, D0 = 1.55 Mg m?3 space group symmetry P21.The structure was determined by the heavy atom method using 2214 independent observed reflections. The conformation of the macrocyclic ring is discussed. 相似文献
16.
5,5-Di t-butyl-2,2-biphenyldiol (I), C20H26O2, crystallizes in the orthorhombic space group P212121 with a = 18.243(2), b = 9.947(2), c = 9.685(3) Å, and Z = 4; 5,5-dimethyl-2,2-biphenyldiol (II), C14H14O2, crystallizes in the monoclinic space group P21/c with a = 9.959(2), b = 7.932(3), c = 15.392(2) Å, = 105.43(2)°, and Z = 4. The aromatic rings are tilted by 52.7(1) and 43.8(1)° to each other in compounds (I) and (II), respectively. Strong intra- and inter-molecular H-bonds connect the molecules in the crystals. 相似文献
17.
Gabriele Bocelli Andrea Cantoni Franca Bigi Giovanni Sartori 《Journal of chemical crystallography》1992,22(6):691-694
The structure of the compound obtained by reaction of AlCl3-promotedm-xilene with 2,6-pyridine dicarbonyldichloride in dichloromethane has been investigated by X-ray diffraction methods. The compound is monoclinic, space groupP21/c,a=13.907(2),b=17.247(3),c=12.042(2) Å,=109.75(4)°. The structure was solved by direct methods and refined by full matrix least-squares to a finalR=6.37 for 3718 independent observed reflections [I>2(I)]. The structure of the compound enables an understanding of the chemical pathway of the synthesis process. 相似文献
18.
Gabriele Bocelli Gianluca Calestani Corrado Rizzoli 《Journal of chemical crystallography》1990,20(3):217-221
Crystals of the title compound are monoclinic (C26H25NO): space groupP21/c,a=16.565(3),b=10.328(2),c=12.621(3) Å,=104.02(3)°. The structure was solved by direct methods and refined by block-matrix least-squares to giveR=0.056 andR
w
=0.061 for 1613 reflections above 2(I). The amide moiety is tilted by 19.3(2)° with respect to the mean aromatic ring plane. The two othergem phenyl rings subtend a dihedral angle of 112.2(4)° to each other. The molecules are joined in the solid by N-HO hydrogen bonds. 相似文献
19.
Gabriele Bocelli Andrea Cantoni Elisabetta Giorgini Giorgio Tosi 《Journal of chemical crystallography》1990,20(5):419-423
A series of complexes between 1-oxide quinolines and 7,7,8,8-tetracyanoquinodimethane has been synthesized and one of them has been analyzed by x-ray diffraction methods. Crystals of the title compound are monoclinic (C15H11NO·C12H4N4), space groupP21/n,a=44.525(4),b=7.326(2),c=6.531(2) Å,=90.23(3)°. The structure was solved by direct methods and refined by block-matrix least-squares to giveR=0.047 for 1865 reflections above 2(I). Molecular dimensions, interplanar distances, empirical method and IR spectra suggest a -* interaction with very low charge-transfer in the complex. 相似文献
20.
Douglas M. Sartore Deyber A. Vargas Medina Marcio D. Bocelli Marcela Jordan-Sinisterra Álvaro J. Santos-Neto Fernando M. Lanças 《Journal of separation science》2023,46(15):2300215
Sample preparation frequently is considered the most critical stage of the analytical workflow. It affects the analytical throughput and costs; moreover, it is the primary source of error and possible sample contamination. To increase efficiency, productivity, and reliability, while minimizing costs and environmental impacts, miniaturization and automation of sample preparation are necessary. Nowadays, several types of liquid-phase and solid-phase microextractions are available, as well as different automatization strategies. Thus, this review summarizes recent developments in automated microextractions coupled with liquid chromatography, from 2016 to 2022. Therefore, outstanding technologies and their main outcomes, as well as miniaturization and automation of sample preparation, are critically analyzed. Focus is given to main microextraction automation strategies, such as flow techniques, robotic systems, and column-switching approaches, reviewing their applications to the determination of small organic molecules in biological, environmental, and food/beverage samples. 相似文献