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1.
Gábor Dörnyei Marietta Bárczai-Beke Gábor Blaskó Péter Péchy Csaba Szántay 《Tetrahedron letters》1982,23(28):2913-2916
Regioselective demethylation of 3,4-dihydropapaveraldine (a) at 7 and 3' positions affords a properly substituted diphenolic key intermidiate (d) for the synthesis of reticuline and N-norreticuline. 相似文献
2.
P. Miranda Jr. J. Zukerman-Schpector J. R. Matos M. F. Máduar E. M. Aricó M. Linardi L. B. Zinner G. Vicentini 《Journal of Thermal Analysis and Calorimetry》2004,75(2):577-582
The complexes [Ln(pic)3(DTSO)3] (Ln=La, Lu and Y; pic=picrate; DTSO=1,3-dithiane-1-oxide) were synthesized and characterized. Indirect structural determination by far infrared
spectroscopy is presented. Results from thermal decomposition of these complexes by TG/DTG and DSC techniques are reported.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
Nelson Durán Klaus Zinner Roberto Casadei de Baptista Carmen C. C. Vidigal Giuseppe Cilento 《Photochemistry and photobiology》1976,24(4):383-388
Abstract— The thiophenyl ester of indole-3-acetic acid and indole-3-acetonitrile produce chemiluminescence in aerated dimethylsulfoxide in the presence of potassium t -butoxide. The emitter is the aromatic aldehyde. In the case of acetonitrile, the other product expected from the cleavage of an intermediate dioxetane, cyanate/isocyanate, has also been identified. Other auxins also chemiluminesce under similar conditions, but the emitters have not been properly identified.
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
4.
Gert Brandl Fritz Kastner Rainer Fritsch Herbert Zinner Albrecht Mannschreck 《Monatshefte für Chemie / Chemical Monthly》1992,123(11):1059-1069
Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke. 相似文献
5.
The mercury perrhenates with the empirical formulas HgReO4 and Hg2ReO5 were prepared by annealing powdered mixtures of mercury(II)oxide and mercury(II)metaperrhenate Hg(ReO4)2 in sealed silica tubes. Their crystal structures were determined from single-crystal X-ray data. HgReO4 crystallizes dimeric with nearly linear O3Re? O? Hg? Hg? O? ReO3 molecular units and Hg2ReO5 has a solid state structure, where Hg(I) and Hg(II) together with oxygen atoms form 14-membered rings, which are condensed to two-dimensionally infinite polycationic nets of composition (Hg22+ · 2 HgO)n. These nets are separated from each other by tetrahedral ReO4? anions. 相似文献
6.
Joseph S. Alper Robert I. Gelb Marietta H. Schwartz 《Journal of inclusion phenomena and macrocyclic chemistry》1991,11(4):333-348
Complexation stoichiometries and formation constants of tri- and tetra-protonated forms of 1,4,8,12-tetraazacyclopentadecane with NO
3
–
, Cl–, IO
3
–
and SO
4
2–
ions are determined by pH potentiometric and13C NMR spectrometric measurements. Estimates of H and S are obtained from the values of the temperature dependent formation constants and acid dissociation constants. All four anions form only 1 : 1 complexes with the triprotonated amine species. NO
3
–
and Cl– form 1 : 1 complexes only with the tetraprotonated amine, while IO
3
–
and SO
4
2–
form both 1 : 1 and 2 : 1 complexes. The complexation behavior is interpreted in terms of solvation and internal hydrogen bonding interactions. 相似文献
7.
G. Vicentini L. B. Zinner S. F. M. Barretto 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Compounds with composition [Ln (ReO4)2 (HMPA)2] ReO4 (Ln=La Nd) and [Ln(ReO4)2(HMPA)4]ReO4 (Ln=Sm-Lu, Y) were synthesized by reaction of HMPA with the hydrated lanthanide perrhenate in ethanol followed by triethyl-orthoformate precipitation. The compounds from lanthanum to gadolinium are soluble enough and behave as 1:1 electrolytes in methanol. The remaining behave as 1:1 electrolytes in nitromethane and acetonitrile. Two types of IR spectra were observed, corresponding to the two different compositions. In all cases bands attributed to ionic and solittings due to coordinated bidentate perrhenate for the lighter and mono dentate for the heavier ones were observed. Splittings and shifts of VPO could arise from at least two non-equivalent PO groups. The band at -1190 or 1180 cm?1 (m) is attributed to a weakly bonded and that at 1125 cm?1 (m) to a strongly bonded, through the phosphoryl oxygen. The v as P-N-C and v s P-N-C bands are shifted to higher frequencies as compared to the free ligand. The absorption spectra of the neodymium compound in the hypersensitive 4G5/2, 2G7/2 ← 4I9/2 transition region were determined. The experimental data permit us to conclude that Nd3+ ions are not located in a cubic site. The nephelauxetic parameter, covalent factor and Sinha's parameter indicate an appreciable covalent character of the ligands: Nd3+ interaction. (CNPq, FAPESP, FINEP). 相似文献
8.
C. A. De Simone E. E. Castellano C. A. Fantin L. B. Zinner G. Vicentini 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The crystal structure of the complex of formula {|Nd(NCS)3 (HMPA)3‖ |Nd(NCS)3 (HMPA)4|} was determined by three-dimensional X-ray diffraction methods and refined anisotropically to a R=0.040. The compound crystallizes in the trigonal system, space group R3 (No 146), with a=19.947(3), b=19.947(3), c=20.106(3) Å, α=β=90, γ=120°, V=6928(4) Å3, M=1891.4, Z=3, Dc=1.360 g cm?3, λ(MoKα)=0.71073 Å, μ=1.4 cm?1, F (000)=2922.01. There are two independent Nd3+ ions located in the three fold axis. One of them, located at the origin (000) is coordinated to nitrogen atoms of three symmetry related NCS? anions which are below the (x y) plane (negative z) and also to the oxygen atoms of three symmetry related HMPA groups above that plane. The coordination polyhedron is a slightly distorted octahedron. The other Nd3+ ion is located at (00,0.5025(1)). It is coordinated to the nitrogen atoms of three symmetry related NCS? anions above the (xy 1/2) plane and to oxygen atoms of three symmetry related HMPA groups below that plane. Another HMPA group has the O and P atoms located on the three-fold axis, above the (xy 1/2) plane. The coordination number is in this case 7 and the polyhedron is a capped trigonal antiprism. The mean distances are: Nd-N=2.44 Å, Nd-0=2.35 Å and Nd-N=2.52 Å, Nd-0=2.36 Å for the octahedron and antiprism configurations, respectively. (CNPq, FAPESP, FINEP) 相似文献
9.
Frederick H. Roos William H. Daly Marietta N. Aniano-Ilao Ioan I. Negulescu 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):275-290
Abstract The synthesis of a variety of substituted bisphenol A polysulfones, including nitro, amino, aminomethyl, ethyl, and methyl derivatives, is described. Nuclear magnetic resonance (NMR) (both proton and carbon, and several 2-D experiments) data confirm conclusions on the substitution site based on arguments on inductive effects in the phenyl rings. The proton ortho to the oxygen in the bisphenol A (BPA) residue is replaced in electrophilic substitution reactions. The degree of substitution was also calculated from the NMR results. The ethyl and methyl derivatives were expected, from the starting reactants, to each have a BPA ring substituted. The NMR data showed that, on the average, this is true. The nitro derivative also has substitution in every BPA ring, while the amino and aminomethyl derivatives have only intermittent BPA rings substituted. Measured degrees of substitution (DS) varied from 0.11 to 2.25. 相似文献
10.
N. T. Zinner G. M. Bruun 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):133-139
A layered system of two-dimensional planes containing fermionic polar molecules can potentially realize a number of exotic quantum many-body states. Among the predictions, are density-wave instabilities driven by the anisotropic part of the dipole-dipole interaction in a single layer. However, in typical multilayer setups it is reasonable to expect that the onset and properties of a density-wave are modified by adjacent layers. Here we show that this is indeed the case. For multiple layers the critical strength for the density-wave instability decreases with the number of layers. The effect depends on density and is more pronounced in the low density regime. The lowest solution of the instability corresponds to the density waves in the different layers being in-phase, whereas higher solutions have one or several adjacent layers that are out of phase. The parameter regime needed to explore this instability is within reach of current experiments. 相似文献