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1.
Fenesan I Popescu R Supuran CT Nicoara S Culea M Palibroda N Moldovan Z Cozar O 《Rapid communications in mass spectrometry : RCM》2001,15(9):721-729
This work discusses the synthesis and the fragmentation patterns for 2-(p-acetylaminosulfonamido)-2-thiono-(5,5-dimethyl-1,3,2-dioxaphosphorinane)(1) and for the p-acetylaminosulfonylamides of O,O-diethylthiophosphoric acid (2), O,O-diphenylthiophosphoric acid (3), dimethylaminocyclohexylthiophosphoric acid (4), and diethylaminophenylthiophosphoric acid (5). A thionamidic-thiolimidic structure was attributed to compounds 1-5, consistent with their IR and NMR spectra. EI mass spectra at 70 eV, high resolution (HR) mass measurements and metastable ion spectra were used to elucidate the fragmentation processes and to determine the kinetic energy release values associated with the metastable ion dissociations. HR accurate mass measurements were used to confirm the compositions of the more abundant ions. 相似文献
2.
S. Cint Pinzaru Cs. Müller S. Tomi M. M. Venter B. I. Cozar B. Glamuzina 《Journal of Raman spectroscopy : JRS》2015,46(7):597-604
While recording SERS spectra of pure β‐carotene at sub‐micromole concentrations for reference purpose, we discovered an unusual spectral response never reported before. In pre‐resonance conditions with the 532‐nm line, SERS of β‐carotene with AgNPs exhibits among the strong υ(CC) mode at 1512 cm−1 unshifted from normal Raman spectrum, additional strong bands at 1649, 1575 and 1387 cm−1 as well as other medium bands not observed in the Raman spectrum of the crystalline powder. Such behavior is explained in terms of selection rules relaxation upon cyclohexene terminal rings of the β‐carotene interaction with the NP surface. AFM images of the SERS system suggested dimers and trimers clustering of the nanoparticles with adsorbed β‐carotene. In light of the new SERS feature the consequences in correct interpretation of the SERS imaging from complex biosystems containing carotenoids are discussed. Relative intensity ratio of the β‐carotene band at 1512 cm−1 and water against concentration allowed a reliable SERS calibration curve for 50 to 500 nmol l−1 concentration range and provided quantitative SERS assessment of the carotenoid content in the sea urchin (Paracentrotus lividus) gonads extracts. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
A method for preliminary evaluation of the correlation time of local dynamics of the polymeric chains, using the experimental nuclear magnetic resonance spin-lattice relaxation data, is proposed. The algorithm is based on the model of the passage of a particle over a potential energy barrier. This method was utilized for some molten polymers and concentrated polymeric solutions. 相似文献
4.
Prof. Dr. Onuc Cozar V. Znamirovschi L. David L. Giurgiu J. Zsako 《Applied magnetic resonance》1992,3(5):849-857
The following copper(II)-dioxime-dichloride compounds: [Cu(G)Cl2]2, [Cu(P)Cl2]2, [Cu(DMG)Cl2]2 and [Cu(O)Cl2]2 (where G=C2H4O2N2, P=C3H6O2N2, DMG=C4H8O2N2, O=C8H14O2N2) were investigated by ESR method. Spectra of powder samples obtained in the g?2 region suggest the presence of triplet ground state (S=1) realized by a weak ferromagnetic exchange coupling. In liquid and frozen solutions the monomeric species (S=1/2) prevail. Some delicate changes in the coordination polyhedra symmetry in terms of ligand molecules and solvents nature were evidence. A 4p-admixture degree of 2% in the dxy ground state was estimated for pseudotetrahedral (Td) species in frozen solutions. 相似文献
5.
A computational scheme for frequency-dependent polarizabilities of open-shell systems by coupled Hartree-Fock perturbation theory is presented. It allows the simultaneous approximate prediction of the involved electronic transition energies and can trivially be extended to imaginary values of the frequency. As a simple application, the dipole polarizability and some related properties of Li atoms are evaluated, the agreement with previous estimates being excellent. 相似文献
6.
L. David O. Cozar L. Sumâlan V. Chis R. Tetean C. Crâciun 《Applied magnetic resonance》1997,13(3-4):571-577
The Cu(II) complexes with 2-N-acetyl-salicylidene-hydrazino-4-chlor-methyl thiazole (L.) and 2-N-acetyl salicylidene-hydrazioo-4-thiazolyl acetic ester (LII) were prepared and investigated by ESR measurements. The powder ESR spectrum at room temperature of CuLIICl is quasi-isotropic (g=2.113), while for CuLIICl is characteristic of monomeric species with axial symmetry (g II)=2.234,g 1=2.073). The isotropic ESR spectra of the CuLCl compounds in DMSO solution suggest the presence of pseudo-tetrahedral monomeric species. The anisotropic spectra were obtained for adsorbed CuLCl DMSO solutions on NaY zeolite. The parallel hyperfine structure shows the coexistence of two magnetic nonequivalent monomeric species. The estimation of some LCAO-MO coefficients using Kivelson and Neiman’s approximation reveals a dominant ionic character for copper-ligand bonds. 相似文献
7.
Nicolae Leopold Simona CîntÎ‐Pînzaru Lszl Szab Daniela Ilean Vasile Chi Onuc Cozar Wolfgang Kiefer 《Journal of Raman spectroscopy : JRS》2010,41(3):248-255
Conjugate acid–base forms of the drug metoclopramide were investigated by Raman spectroscopy in aqueous solutions and by surface‐enhanced Raman scattering (SERS), when the molecules were adsorbed on colloidal silver surfaces. Raman spectra were recorded at pH values below 8, metoclopramide being poorly water soluble at higher pH values. The SERS spectra of metoclopramide were recorded in the 3–11 pH range, even in spite of its low solubility at basic pH values. The Raman and SERS spectra were assigned by means of density functional theory (DFT) calculations. By monitoring several SERS marker bands, the protonated, neutral or the coexistence of both molecular species adsorbed on the colloidal silver particles could be evidenced. The adsorbate orientation was deduced to be perpendicular to the metal surface for the protonated molecular species and tilted for the neutral metoclopramide molecular species. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
The FT-Raman spectrum of cupferron, [PhN2O2]NH4 and the micro-Raman spectra of the new corresponding cobalt(II) cupferronato complexes, CoL2A2, L = PhN2O2, a = H2O, MeOH, o-C6H4(NH2)2, p-C6H4(NH2)2 and CoL2A, a = (-C6H4NH2-p)2 were recorded and discussed. All the complexes show a Raman band at about 1302 cm1 and the characteristic v(N-N) and δ(ONNO) modes of the anionic ligand. the vibrational analysis of the title compounds reveals the electron delocalisation over the N-nitroso-N-hydroxylaminato (ONNO) unit, as well as the bidentate coordination of the cupferronato ligand to the metal center through the oxygen atoms. 相似文献
9.
The local symmetry and interaction between paramagnetic ions in xMoO3(1 ? x)[2 P2O5PbO] glasses with 0.5 ? x ? 50 mol% are investigated by EPR spectroscopy. For x ? 10 mol% the isolated Mo5+ ions surrounded by five oxygen ligands in a square-pyramidal form (C4v symmetry) prevail. The short range disorder in the environment of Mo5+ ions is not significantly (ΔR/R ≈ 2%). At high molybdenum content (x > 20 mol%) the dipole–dipole and superexchange coupled Mo5+ ions appear and their number increases with the MoO3 content. These two aspects are also correlated with the network modifier and former role of molybdenum oxide in function of its concentration. Thus a strong depolymerization of the phosphate structure and the formation of P–O–Mo or Mo–O–Mo bonds in studied glasses appear. 相似文献
10.
O. Cozar L. David V. Chiş C. Cosma V. Znamirovschi G. Damian I. Bratu Gh. Bora 《Applied magnetic resonance》1995,8(2):235-242
Powder ESR spectra of the [Cu2(Asp)4](H2O)2 complex show the existence of Cu(II) acetate like dimers characterized by a strong antiferromagnetic exchange interaction (J=?288 cm?1). In pyridine-dimethylformamide solutions the monomeric species prevail. Two different monomeric species, the Cu(DMF)4 of planar-distorted tetrahedral (Td) symmetry and the Cu(Asp)2(DMF)2 with elongated tetrahedral-octahedral symmetry were evidenced in DMF solution adsorbed on NaY zeolite. In 40 % Py+60 % DMF solution two monomeric species were also identified. These are Cu(Asp)2(DMF)2 and Cu(Asp)2(Py)2, the last species having a CuN2O2 chromophore in atrans squareplanar arrangement. In pyridine Cu(II)-aspirinate solution only the Cu(Py)4 monomeric species of CuN4 chromophore was evidenced. 相似文献