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1.
T. S. Martins J. R. Matos G. Vicentini P. C. Isolani 《Journal of Thermal Analysis and Calorimetry》2005,82(1):77-82
Summary Rare earth picrate (RE) complexes with L-lysine (Lys) were synthesized and characterized. Elemental analysis (CHN), EDTA titrations and thermogravimetry data suggest
a general formula RE(pic)3·2Lys·2H2O, where RE=La-Lu (without Pm) and Y, pic=picrate). IR spectra suggest that Lys is coordinated to the central ion through the nitrogen of the α-amino group. Parameters
obtained from the absorption spectrum of the Nd compound indicated that the metal-ligand bonds are essentially electrostatic.
Emission spectrum and biexponential behavior of the luminescence decay of the Eu compound suggest the existence of polymeric
species. Thermogravimetric/derivative thermogravimetric (TG/DTG) and differential scanning calorimetry (DSC) curves of all
complexes are very similar, with five events. The final products are the corresponding rare earth oxides and their X-ray diffraction
patterns are identical to the calcinated oxides.</o:p> 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.
Nora Jannsen Dr. Stefano Diodati Nicola Dengo Francesca Tajoli Dr. Nicola Vicentini Dr. Giacomo Lucchini Prof. Adolfo Speghini Prof. Denis Badocco Prof. Paolo Pastore Prof. Silvia Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13624-13634
The aim of this work was i) to develop a hydrothermal, low-temperature synthesis protocol affording the upconverting hexagonal phase NaYF4 with suitable dopants while adhering to the “green chemistry” standards and ii) to explore the effect that different parameters have on the products. In optimizing the synthesis protocol, short reaction times and low temperatures (below 150 °C) were considered. Yb3+ and Er3+ ions were chosen as dopants for the NaYF4 material. Within the context of the second goal, parameters including nature of the precursors, treatment temperature, and treatment time were investigated to afford a pure hexagonal crystalline phase, both in the doped and undoped materials. To fully explore the synthesis results, the prepared materials were characterized from a structural (XRD), compositional (XPS, ICP-MS), and morphological (SEM) point of view. The upconverting properties of the compounds were confirmed by photoluminescence measurements. 相似文献
4.
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
5.
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
6.
A two-dimensional steady-sate analysis of semi-infinite brittlecrack growth at a constant subcritical rate in an unboundedfully-coupled thermoelastic solid under mixed-mode thermomechanicalloading is made. The loading consists of normal and shear tractionsand heat fluxes applied as point sources (line loads in theout-of-plane direction). A related problem is solved exactly in an integral transformspace, and robust asymptotic forms used to reduce the originalproblem to a set of integral equations. The equations are partiallycoupled and exhibit operators of both Cauchy and Abel types,yet can be solved analytically. The temperature change field at a distance from the moving crackedge is then constructed, and its dominant term is found tobe controlled by the imposed heat fluxes. The role of this termis, indeed, enhanced if the heat fluxes serve to render thecrack as a net heat source/sink for the solid, as opposed tobeing a transmitter of heat across its plane. More generally,the influence of the thermoelastic coupling on this field, aswell as other functions, is found to increase with crack speed. 相似文献
7.
Chiara B. Vicentini Manuela Mazzanti Carlo F. Morelli Maurizio Manfrini 《Journal of heterocyclic chemistry》2000,37(1):175-180
Ethyl 2-amino-3-methoxycarbonyl-4-oxo-2-pentenoate (3) reacts with hydroxylamine or hydrazines to give isoxazole and pyrazole ortho-dicarboxylic acid esters 4 and 5, respectively. Partial hydrolysis of diesters 4 and 5 afforded the corresponding dicarboxylic acid monoesters 6 and 7. Amidation of the intermediate acid chlorides 8,9 followed by hydrolysis of 4-methylesters 10, 11 gave the title compounds 1 and 2, respectively. 相似文献
8.
P. Giori A. C. Veronese T. Poli C. B. Vicentini M. Manfrini M. Guarneri 《Journal of heterocyclic chemistry》1986,23(2):585-588
The reaction of pyrazolo[4,3-c][1,2,5]oxadiazin-3(5H)-ones 1 with carbanions prepared in situ from compounds containing an activated methylene group afforded pyrazolo[3,4-b]pyrazines 4–13 in good yields. The possible reaction mechanism is proposed and discussed. 相似文献
9.
C. B. Vicentini A. C. Veronese M. Guarneri M. Manfrini P. Giori S. Guccione 《Journal of heterocyclic chemistry》1994,31(6):1477-1480
Thiation of N-(1-tert-butyl-3-methylpyrazol-5-yl)carboxamides 2 with the Lawesson reagent afforded the corresponding thiocarboxamides 3 . Heating of 3 in formic acid gave the N-dealkylated thiocarboxamides 4 which were cyclized into 4H-pyrazolo[1,5-c][1,3,5]thiadiazine-4-thiones 5 by treatment with thiophosgene. 相似文献
10.