共查询到20条相似文献,搜索用时 15 毫秒
1.
Jasmina M. Dimitrić Marković Dragan S. Veselinović Jelisaveta M. Baranac Tanja P. Brdarić 《光谱学快报》2013,46(3):104-115
Complexation of aluminum (III) with cyanidin, a natural anthocyanidin molecule, has been investigated in methanol and buffered solutions of pH 3.0 and 4.0. Electronic absorption spectroscopy was performed to characterize the stoichiometry and stability of the complexes formed. In investigated solvents, aluminum bonded moderately to cyanidin requiring large mole ratios of the components (up to 200) for the access of complexation. Molar ratio plots showed the formation of only one complex with stoichiometry aluminum (III):cyanidin of 1∶1 in both investigated media. Semiempirical calculations, performed in the Austin Model 1 parameterization, enabled the determination of the structural features of free compounds as well as complex structural modifications caused by chelation of Al(III). 相似文献
2.
《光谱学快报》2013,46(4-5):497-504
Abstract The hydrazone ligand, methyl‐2‐pyridyl ketone benzoyl hydrazone (L), and its complexes with rare earth nitrates have been synthesized. These new complexes with the general formula of Ln(L)2(NO3)3 · nH2O (where Ln=La, n=5.5; Ce, Pr, n=5; Nd, Eu, n=4) were characterized by mass spectra, elemental analysis, IR spectra, thermal analysis, UV spectra, molar conductivity, and luminescent spectra. All the complexes are stable in air. The results show that the lanthanide ions in each complex are coordinated through oxygen and nitrogen atoms of the ligand, the oxygen atoms of the nitrate, and coordinated water molecules. The amide‐oxygen atoms of L coordinate to the Ln ions in its keto‐form. Tentative structures for the complexes have been proposed. 相似文献
3.
Paramagnetic centers in 3,4-dihydroxyphenylalanine–melanin and its complexes with Fe(III) were examined by electron paramagnetic
resonance (EPR) spectroscopy. Paramagnetic centers of melanin play an important role in detoxification of environment and
they reveal high activity in binding of metal ions. Two different signals were observed in EPR spectra: lines of o-semiquinone free radicals and lines of paramagnetic Fe(III). Amplitudes of EPR lines of both free radicals and iron ions
decrease with increasing Fe(III) content in melanin–metal ion complexes. Free radical concentrations in the melanin samples,
g-factors, amplitudes and line widths of EPR spectra were determined. It was stated that fast spin–lattice relaxation processes
exist in both free radical system and paramagnetic iron ions in melanin complexes. 相似文献
4.
《光谱学快报》2013,46(4-5):431-445
Abstract A new, simple, and sensitive quantitative spectrophotometric method for the rapid determination of zinc(II) using six azo compounds based on 3‐amino‐1,2,4‐triazole, namely {3‐(2,4‐dihydroxy‐1‐phenylazo)‐1,2,4‐triazole) (I), 3‐(2‐hydroxy‐5‐methyl‐1‐phenylazo)‐1,2,4‐triazole) (II), 3‐(2‐hydroxy‐5‐acetyl‐1‐phenylazo)‐1,2,4‐triazole) (III), 3‐(2‐hydroxy‐5‐ethylcarboxylate‐1‐phenylazo)‐1,2,4‐triazole) (IV), 3‐(2‐hydroxy‐5‐formyl‐1‐phenylazo)‐1,2,4‐triazole) (V), and 3‐(2‐hydroxy‐5‐bromo‐1‐phenylazo)‐1,2,4‐triazole) (VI), has been developed for use in aqueous media containing 40% (v/v) methanol. Linear calibration graphs are obtained up to 2.6, 5.9, 5.2, 5.2, 8.2 and 9.0 µg mL?1 using ligands I, II, III, IV, V, and VI, respectively. Absorption maxima, molar absorptivities, and Sandell's sensitivities of 1:2 (M:L) complexes were found to be 490, 530, 505, 520, 550, and 510 nm, 4.86×104, 2.10×104, 1.26×104, 0.10×104, 0.19×104, and 0.29×104 L mol?1 cm?1, and 0.0014, 0.0031, 0.0052, 0.0662, 0.0348, and 0.0225 µg cm?1 for ligands I, II, III, IV, V, and VI, respectively. Using the masking agents, the color reactions are free from interference by more than 30 ions investigated. The method has been applied to the spectrophotometric determination of trace amounts of zinc in pharmaceutical formulations and human hair samples. A study of some zinc solid complexes showed that chelation takes place through one nitrogen atom of the azo group and proton displacement from the hydroxyl group. 相似文献
5.
《光谱学快报》2013,46(3):319-342
Abstract The application of nuclear magnetic resonance (NMR) spectroscopy, hyphenated NMR, and diffusion‐ordered spectroscopy (DOSY) to the characterization of mango juice, as an example of a complex food mixture, is described. The compositional changes taking place as a function of ripening were followed, and selected metabolites were quantified by integration of the corresponding NMR peaks. In this way, an overall view of the metabolite changes is obtained, enabling the study of the biochemical mechanisms involved in the ripening process. More than 50 compounds were identified by 1D‐ and 2D‐NMR, but many ambiguous assignments remain due to spectral overlap or insufficient coupling information. The use of Liquid Chromatography (LC‐NMR) and LC‐NMR/Mass Spectrometry (MS) enables a fuller characterization of the soluble pectin fraction to be made; its dependence on ripening stage is discussed. Finally, DOSY adds information on the Mr of many metabolites, including the pectin fractions of ripe and unripe mango juices, and enables further peak assignments to be made. 相似文献
6.
6-Hydroxy chromone-3-carbaldehyde-(4′-hydroxy) benzoyl hydrazone (L) and its Ln (III) complexes, [Ln = La, Nd, Eu and Tb]
have been prepared and characterized on the basis of elemental analyses, molar conductivities, mass spectra, 1H NMR, thermogravimety/differential thermal analysis (TG-DTA), UV-vis spectra, fluorescence spectra and IR spectra. The formula
of the complex is [Ln L·(NO3)2]·NO3. Spectrometric titration, ethidium bromide displacement experiments and viscosity measurements indicate that Eu (III) complex
bind with calf-thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constant of Eu (III) with DNA
was 2.48 × 105 M−1 through fluorescence titration data. 相似文献
7.
《光谱学快报》2013,46(4-5):569-581
Abstract Steady‐state fluorescence and phosphorescence of inclusion complexes of cyclodextrins (CDs) with fluorescent nonionic surfactant and 1‐bromonaphthalene (BN) are described in detail. The inclusion of the hydrophobic moiety of surfactants inside the cavity of CDs led to enhanced monomer‐like fluorescence with a bathochromic shift of λex and a hypsochromic shift of λem. 1H‐NMR provides additional evidence for deep inclusion of the hydrophobic moiety of surfactants. BN can squeeze into more hydrophobic cavity of β‐CD that has accommodated the hydrophobic moiety of a surfactant and show its phosphorescence and remarkable quenching effect on the fluorescence of a surfactant in aerated aqueous solution. Stern–Volmer quenching depends on the inclusion of the phenyl rings of surfactants and BN into the cavity of CDs. Comparison of molecular sizes reveals that further inclusion of BN into the cavity of β‐CD occupied by a surfactant may force the flexible octyl group of a surfactant to deform to a greater extent, and close‐packing complexes were obtained. In the case of heptakis(2,6‐di‐O‐methyl)‐β‐CD, BN only binds to its cavity opening due to the steric hindrance of methyl substituents at the rim of its cavity. 相似文献
8.
《光谱学快报》2013,46(5-6):429-440
Four new metal complexes of Cu(II), Ni(II), Zn(II) and Co(III) with Schiff base derived from 4‐methoxybenzaldehyde and 1,2‐bis(p‐aminophenoxy)ethane have been prepared and characterized by magnetic susceptibility, conductance measurements, elemental analyses, UV–Vis, 1H NMR and IR spectra studies. The magnetic and spectroscopic data indicate an octahedral geometry for the six‐coordinate complexes. The ligand was used for complexation studies. Stability constants were measured by means of a conductometric method. Furthermore, the stability constants for complexation between ZnCl2, Cu(NO3)2 and AgNO3 salts and ligand (L) in 80% dioxane–water and pure methanol were determined from conductance measurements. In 80% dioxane–water, he stability constants (log Ke) increase inversely with the crystal radii in the order Ag(I) < Zn(II) < Cu(II). 相似文献
9.
Journal of Applied Spectroscopy - Tb3+-doped Zn–Al (Zn–Al–Tb) hydrotalcites with tunable blue-green emission synthesized by co-precipitation. The compositions and properties of... 相似文献
10.
《Journal of Macromolecular Science: Physics》2013,52(4):763-774
Abstract The introduction of 2,9,16,23‐tetramide‐Fe(III)phthalocyanine [Fe(III)taPc] units into phosphorylated poly(N‐vinylcarbazole) yields an amorphous grafted polymer containing free carbazolyl groups, phosphonic acid attached to carbazolyl groups, and grafted Fe(III)taPc units as evidenced by infrared spectroscopy. Several thermal transitions were detected by differential scanning calorimetry (DSC). The thermodegradation of the grafted sample, analyzed by simultaneous thermogravimetry‐differential thermal analysis (TG‐DTA), showed successive endo‐ and exothermal reactions resulting from the development of a cross‐linked structure. To determine kinetic parameters, both isothermal and dynamic experiments were performed at the different steps of the degradation process and theoretical methods were applied. 相似文献
11.
《光谱学快报》2013,46(4):421-436
Abstract Phencyclone, 1, reacted with N‐(2,6‐dimethylphenyl)maleimide, 2a; with N‐(2,6‐diethylphenyl)maleimide, 2b; and with N‐(2,6‐diisopropylphenyl)maleimide, 2c, respectively, to yield the corresponding Diels–Alder adducts, 3a–c. The adducts were extensively characterized by NMR (7 T) at ambient temperatures using one‐ and two‐dimensional (1D and 2D) proton and carbon‐13 techniques for assignments. Slow exchange limit (SEL) spectra were observed, demonstrating slow rotations on the NMR timescales, for the unsubstituted bridgehead phenyl groups [C(sp3)–C(aryl sp2) bond rotations] and for the 2,6‐dialkylphenyl groups [N(sp2)–C(aryl sp2) bond rotations]. Substantial magnetic anisotropic shifts were seen in the adducts. For example, in the N‐(2,6‐dialkylphenyl) moieties of the adducts, one of the alkyl groups is directed “into” the adduct cavity, toward the phenanthrenoid portion, and these “inner” alkyl proton NMR signals were shifted upfield. Thus, in CDCl3, the “inner” methyl of adduct 3a exhibits a proton resonance at ?0.13 ppm, upfield of tetramethylsilane (TMS); the “inner” ethyl group signals from 3b appear at 0.026 ppm (CH2, quartet), and ?0.21 ppm (CH3, triplet); and the “inner” isopropyl group from 3c is seen at ?0.06 ppm (methine, approx. septet) and ?0.39 ppm (CH3, doublet). Proton NMR of the crude N‐(2,6‐dialkylphenyl)maleamic acids (used as precursors of the maleimides, 2a–c) exhibited two sets of AB quartet signals, suggesting possible conformers from hindered rotation in the amide groups about the HN–C?O bonds. 相似文献
12.
M.N.A. Abdullah M.S. Mahbub S.K. Das A.S.B. Tariq M.A. Uddin A.K. Basak H.M. Sen Gupta F.B. Malik 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):477-486
Full finite-range macroscopic calculations in the distorted-wave Born approximation have been performed using the molecular
and Michel α-nucleus potentials to analyze the angular distributions of cross-sections of the 27Al(α, d)29Si reaction, at 26.5 and 27.2 MeV incident energies, leading to seven transitions up to the excitation energy E
X = 4.08 MeV of the final nucleus. The parameters of the two types of the α-nucleus potentials are determined from the elastic-scattering
data. Both the molecular and Michel potentials, without any adjustment to the parameters needed to fit the elastic-scattering
data, are able in most cases to reproduce, simultaneously, the absolute cross-sections particularly at large angles, where
the previous calculations failed to reproduce by orders of magnitude, and the gross pattern of angular distributions of the
reaction. The deuteron-cluster spectroscopic factors for most of the seven transitions, deduced using the two α-27Al potentials, differ from those obtained in earlier works. The spectroscopic factor for the ground-state transition, deduced
in the present work for the 25.8 MeV data, agrees well with the shell model prediction.
Received: 15 July 2002 / Accepted: 8 August 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: akbasak2001@Yahoo.com
Communicated by G. Orlandini 相似文献
13.
S. M. Ashraf Sharif Ahmad Uffana Riaz 《Journal of Macromolecular Science: Physics》2013,52(6):1109-1123
Nanocomposites of montmorillonite (MMT) with poly(1‐naphthylamine) (PNA) is investigated for the first time by emulsion polymerization using three different oxidants. Polymerization of PNA was confirmed by Fourier transformation infrared (FT‐IR) as well as UV‐visible spectra. The in situ intercalative polymerization of PNA within MMT layers was confirmed by FT‐IR, X‐ray diffraction, conductivity; scanning electron microscopy (SEM) as well as transmission electron microscopy studies. X‐ray diffraction revealed intercalated as well as exfoliated structures of PNA/MMT nanocomposites, which were compared with the reported polyaniline‐MMT nanocomposites. It was found that the increase in the concentration of PNA in the interlayer galleries of MMT led to destruction of the layered clay structure resulting in exfoliation of the nanocomposite. Conductivity of the nanocomposites was found to be in the range of 10?3 to 10?2 S cm?1 which was found to be higher than the ones reported for polyaniline‐clay nanocomposites as well as PEOA‐OMMT nanocomposites at similar concentrations of intercalated species. The morphology of PNA/MMT nanocomposites was found to be governed by the nature of the oxidant used. 相似文献
14.
Detlef‐M. Smilgies Peter Busch Christine M. Papadakis Dorthe Posselt 《Synchrotron Radiation News》2013,26(5):35-42
FEMTO, a femtosecond (fs) X-ray source based on laser interaction with a relativistic electron beam, began operation in the fall of 2006. It is installed at the μXAS beamline of the Swiss Light Source (SLS) at the Paul Scherrer Institut, Villigen. “Laser slicing” of an electron beam has first been proposed and demonstrated at the ALS [] and has recently been implemented at BESSY [2] to generate fs soft X-rays (1–2 keV) with variable polarization. FEMTO is the first undulator source providing tunable, fs hard X-rays in the range 4.5–12 keV for laser/X-ray pump-probe absorption and diffraction experiments. 相似文献
15.
M. Rajender Reddy Putta Venkat Reddy Yata Praveen Kumar A. Srishailam Navaneetha Nambigari S. Satyanarayana 《Journal of fluorescence》2014,24(3):803-817
The novel ligand (dmbip) 2-(4-N, N-dimethylbenzenamine)1H-imidazo[4, 5-f][1, 10]phenanthroline and its complexes [Ru(phen)2dmbip]2+ (1), [Ru(bpy)2dmbip]2+ (2), [Co(phen)2dmbip]3+ (3) and [Co(bpy)2dmbip]3+ (4) [where phen?=?1, 10-phenanthroline, bpy?=?2, 2′-bipyridine], have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H NMR, 13C NMR and Mass spectra. The DNA binding properties of the complexes were investigated by absorption, emission, quenching studies, light switch “on and off”, salt dependent, sensor (cation and anion) studies, viscosity measurements, cyclic voltammetry, molecular modeling and docking studies. The four complexes were screened for Photo cleavage of pBR322 DNA, antimicrobial activity and cytotoxicity. The experimental results indicate that the four complexes can intercalate into DNA base pairs. The DNA-binding affinities of these complexes follow the order [Ru(phen)2dmbip]2+ > [Co(phen)2dmbip]3+ > [Ru(bpy)2dmbip]2+ > [Co(bpy)2dmbip]3+. 相似文献
16.
Novel poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes have been synthesized by an improved procedure
using the Atherton–Todd reaction conditions. N-ethyldiisopropylamine has been used as a mild base and propylene oxide as an
acid scavenger in order to obtain poly(oxyethylene phosphate) in yield and purity higher than those achieved by conventional
methods. The compounds have been characterized by 1H, 13C, and 31P NMR and FTIR techniques. Their absorption, fluorescent excitation and emission spectra of chloroform and abs. ethanol solutions
have been recorded and studied. The luminescent quantum yields and decay times have been determined and a dependence on the
length of the oxyethylene spacer between phosphate groups has been established. The new polymer complexes are water soluble
and have increased luminescence decay time in comparison with corresponding ternary complexes. 相似文献
17.
《光谱学快报》2013,46(5-6):461-475
The 1H‐ and 13C‐NMR spectra of 1‐β‐d‐glucopyranosyl‐1,2,3‐triazole‐4,5‐dimethyl carboxylate, 1‐β‐d‐glucopyranosyl‐1,2,3‐triazole‐4,5‐dicarboxamide, ‐dialkylcarboxamide‐N‐nucleosides 4–18, and 6‐amino‐4H‐1‐(1‐β‐d‐glucopyranosyl)‐8‐hydroxy‐1,2,3‐triazolo[4,5‐e][1,3]‐diazepin‐4‐one 19 had been studied. Resonance signals and anomeric configurations were assigned by homo‐ and heteronuclear two dimensional methods (DQF‐COSY, HSQC, HMBC, HMQC, ROESY). 相似文献
18.
Tetrakis‐(4‐chlorophenylthio)‐butatriene (3a) and tetrakis‐(tert‐butylthio)‐butatriene (3b) were synthesized, and their crystal structures were determined. The compound 3a is monoclinic, space group P21/c, a=6.9785(8), b=8.6803(9), c=22.884(2) Å, β=93.887(6)o, V=1383.0(3) Å3, Z=2. The compound 3b is monoclinic, space group P21/n, a=11.0615(6), b=10.8507(4), c=11.2717(6) Å, β =116.427(2)o, V=1211.5(1) Å3, Z=4. The title compounds 3a and 3b reside on an inversion center so that only half of the molecule is crystallographically unique. Both compounds are not planar. The crystal structures of 3a and 3b have cumulated double bonds. The C7–C8–C8i and C5–C6–C6i angles that show the linearity in both structures, respectively, are 176.4(3)° in 3a and 175.6(2)° in 3b. 相似文献
19.
M.S. Attia A.O. Youssef Amr A. Essawy M.S.A. Abdel-Mottaleb 《Journal of luminescence》2012,132(10):2741-2746
Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10?9–5.8×10?6 and 5×10?8–1.0×10?6 mol L?1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10?9–3.2×10?5 and 5×10?8–8.0×10?6 mol L?1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10?9 and 1.0×10?8 mol L?1 for NFLX and 1.6×10?10 and 2.0×10?8mol L?1 for GFLX. The limit of quantification (LOQ) is 9×10?9 and 3.0×10?8 and 4.8×10?10 and 6.0×10?8 in case of Eu and Tb, respectively. 相似文献
20.
Hantao Zou Jianming Jiang Shenglin Yang 《Journal of Macromolecular Science: Physics》2013,52(4):581-592
A series of poly(trimethylene‐co‐butylene terephthalate) (PTBT) copolymers were prepared by direct esterification followed by polycondensation. The composition and sequence distribution of the copolymers were investigated by nuclear magnetic resonance (NMR). The results demonstrate that the synthesized PTBT copolymers are block copolymers and the content of poly(butylene terephthalate) (PBT) units incorporated into the copolymers is always less than that in the polymerization feed. The 1,4‐butanediol consumption by a side reaction leads to a relatively lower content of PBT units in the resultant copolymers. At the same time, the PBT and poly(trimethylene terephthalate) (PTT) sequence length distributions in the copolymers are different. The PBT segments favor a longer sequence length than do the PTT segments in their corresponding enriched copolymers. The crystallization rate of the copolymers becomes lower than the homopolymers, especially for PTT‐enriched copolymers. Compared with the PTT segment, the presence of PBT segments in the copolymers seems to accelerate crystallization. A wide‐angle X‐ray diffraction (WAXD) analysis indicates PTT and PBT units do not co‐crystallize. The reduced melting temperatures of the copolymers may be attributed to a smaller lamellar thickness and lateral size due to short sequence lengths. 相似文献