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1.
A series of Ln(III) complexes with pyridine carboxylic acid-N-oxides (L) Ln-L, and mixed ligand complexes of Ln-L plus bipyridine (bipy) or 1,10-phenanthroline (O-phen) (X) Ln-L-X have been studied. These complexes were characterized in solution using Nd(III) absorption in the spectral range of the 4I 9/2 → 4G 5/2 transition corresponding to the hypersensitive band, and in the solid state with the use of IR and Eu(III) luminescence spectroscopy. In solutions a series of Nd(III) complexes and mixed ligand complexes has been examined and the formation of binary LnL and LnL 2 complexes and mixed ligand LnL 2X complexes evidenced. Solid complexes of Eu(III) with nicotinic acid N-oxide and ternary with nicotinic acid N-oxide plus phen were studied with the use of Eu(III) luminescence lifetime measurements and IR spectroscopy, proving the formation of binary [Eu(nicN-oxide) 3(H 2O) 2].2H 2O and ternary [Eu(nicN-oxide) 3phen].H 2O complexes. 相似文献
2.
Complexation and photophysical properties of complexes of lanthanide ions, Ln(III), with diethyl(phthalimidomethyl)phosphonate ligand, DPIP, were studied. Interactions between Ln(III) and DPIP were investigated using Nd(III) absorption and Eu(III) and Tb(III) luminescence (emission and excitation) spectra, recorded in acetonitrile solution containing different counter ions (NO 3-, Cl - and ClO 4-). Results of the absorption spectroscopy have shown that counter ions play a significant role in the complexation of Ln(III)/DPIP complexes. Studies of luminescence spectra of Eu(III) and Tb(III) ions proved that the formation of Ln(III)/DPIP complexes of stoichiometry Ln:L=1:3 is preferred in solution. Based on the results of elemental analysis, Nd(III) absorption spectra and IR and NMR data, it was shown that the DPIP ligand binds Ln(III) ions via oxygen from phosphoryl group, forming complexes of a general formula Ln(DPIP) 3(NO 3) 3·H 2O, in which the NO 3- ions are coordinated with the metal ion as bidentate ligands. Luminescent properties and energy transfer, from the ligand to Ln(III) ions in the complexes formed, were studied based on the emission and excitation spectra of Eu(III) and Tb(III). Their luminescent lifetimes and emission quantum yields were also measured. 相似文献
3.
The optical absorption spectra of [Nd(acac) 3(H 2O) 2]·H 2O, [Nd(acac) 3(im) 2] and [Nd(acac) 3(pz) 2] (where acac is the anion of acetylacetone, im is imidazole and pz is pyrazole) complexes in the visible region have been analyzed. The transition 4G 5/2← 4I 9/2 located near the middle of the visible region (17,500 cm ?1) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f–4f transitions. It is overlapped by a less intense transition 2G 7/2← 4I 9/2. The band shapes of the hypersensitive transition show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of changes in the environment about the Nd(III) ion in the various solutions and suggests coordination of a solvent molecules. Pyridine has been found especially effective in promoting 4f–4f electric-dipole intensity. The DMSO invades the complexes and replaces the water molecules and heterocyclic amines from the coordination sphere. Two DMSO molecules coordinate and the complexes acquire similar structure, [Nd(acac) 3(DMSO) 2] in solution. The oscillator strength and the band shape of the hypersensitive transition of all the complexes remains the same in this solvent. The IR spectra and the NMR spectra of the complexes have also discussed. 相似文献
4.
We have studied the optical absorption spectra of trivalent lanthanide(III) β-diketones. The enhancement in intensity of the hypersensitive transitions of Eu(III) 5D 0→ 7F 2 and Tb(III) 5D 4→ 7F 5 and 5D 4→ 7F 2 complexes was observed in various solution mediums. The oscillator strength for the intraconfigurational transitions has been determined using Judd-Ofelt theory. The change in the oscillator strength and band shape with respect to solvent type is rationalized in terms of ligand (solvent) structure and coordination properties. The intensity of hypersensitive transitions is found to be highly influenced in DMF solution. Electronic spectral studies of the Pr(III) and Nd(III) complexes in different solvents, which differ with respect to donor atoms, reveal that the chemical environment around the lanthanide ion has great impact on f-f transitions and any change in the environment in terms of solvent results in modifications of the spectra. 相似文献
5.
Designing and introducing novel wheel-shaped supramolecular as host complexes with new magnetic properties is the theme of the day. So in this study, new eight binuclear chromium (III) complexes, as models of real chromium-wheel host complexes, were designed based on changing of bridged-ligands and exchange coupling constants (J) of them were calculated using the broken symmetry density functional theory approach. Substitution of fluorine ligand in fluoro-bridged model [Cr 2F(tBuCO 2) 2(H 2O) 2(OH) 4] ?1 by halogen anions (Cl ?, Br ? and I ? ) decreased the antiferromagnetic exchange coupling between Cr(III) centres such that by going from F ? to I ? the J values became more positive. In the case of hydroxo-bridged model [Cr 2OH(tBuCO 2) 2(H 2O) 2(OH) 4] ?1, replacement of hydroxyl by methoxy anion (OMe ?) strengthened the antiferromagnetic property of the complex but substitution by sulfanide (SH ?) and amide (NH 2?) anions weakened it and changed the nature of complexes to ferromagnetic. Because of their different magnetic properties, these new investigated complexes can be suggested as interesting synthetic targets. Also, the J value changes due to ligand substitution were evaluated and it was found that the Cr–X bond strength and partial charges of involved atoms were the most effective factors on it. 相似文献
6.
The results of our investigation on the sensitized luminescence properties of three Eu(III) ??-diketonate complexes of the form [Eu 2(fod) 6(??-bpm)], [Eu(fod) 3(phen)] and [Eu(fod) 3(bpy)] and 4 f?C4 f absorption properties of their Er(III) analogues ( fod = anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione, bpm = 2,2??-bipyrimidine, phen = 1,10-phenanthroline and bpy = 2,2??-bipyridyl) in a series of non-aqueous solvents are presented. The Eu(III) complexes are highly luminescent and their luminescence properties (intensity and band shape) are sensitive to the changes in the inner coordination sphere of the Eu(III) ion. The luminescence intensity of the mononuclear complexes in pyridine is drastically decreased. The coordination structure of the complexes in pyridine is transformed into a more symmetrical one which results into a slow radiative rate of the emission from the complexes. The ancillary ligands, phen and bpy are found better co-sensitizers as compared to the bpm to sensitize Eu(III)-luminescence. The 4 f?C4 f absorption properties (oscillator strength and band shape) of the Er(III) complexes demonstrate that 4G 11/2 ?? 4I 11/2 and 2H 11/2 ?? 4I 15/2 hypersensitive transitions of Er(III) are very sensitive in some coordinating solvents which reflects complex?Csolvent interaction in solution. The hypersensitive transitions of [Er(fod) 3(phen)] remain unaffected in any of the solvents and this complex retains its bulk composition in solution. The erbium complexes as well as the Er(fod) 3 chelate are invaded by DMSO. This solvent enters the inner coordination sphere by replacing heterocyclic ligand and the complexes acquire similar structure [Er(fod) 3(DMSO) 2] in this solvent. The results reveal that the luminescence and absorption properties of lanthanide complexes in solution can be controlled by tuning the coordination structure through ancillary ligands and donor solvents. This work shall prove useful in designing new biological applications with such probes. 相似文献
7.
1-(4-Aminoantipyrine)-3-tosylurea (H 2L) and its three lanthanide (III) complexes, M(H 2L) 3 3NO 3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10 -5 M, [DNA]=(0-1) ×10 -5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(ε a – ε f) versus [DNA] for the titration of DNA with the complex. 相似文献
8.
Six new lanthanide(III) complexes (i.e., [Ln(L) 2(NA) 1.5]·3H 2O, where Ln=La(III), Pr(III), Nd(III), Sm(III), Gd(III), and Ce(III) and L and NA indicate N 2H 4 and C 10H 6(1 -O)(2 -COO), respectively) with 1-hydroxy-2-naphthoic acid [C 10H 6(1 -O)(2 -COOH)] and hydrazine (N 2H 4) as co-ligands were characterized by elemental, FTIR, UV-visible, and XRD techniques. In the FT-IR spectra, the N-N stretching frequency in the range of 981–949 cm −1 demonstrates evidence of the presence of coordinated N 2H 4, indicating the bidentate bridging nature of hydrazine in the complexes. These complexes show symmetric and asymmetric COO − stretching from 1444 to 1441 cm −1 and 1582 to 1557 cm −1, respectively, indicating bidentate coordination. TG-DTA studies revealed that the compounds underwent endothermic dehydration from 98 to 110 °C. This was followed by the exothermic decomposition of oxalate intermediates to yield the respective metal oxides as the end products. From SEM images, the average size of the metal oxide particles prepared by thermal decomposition of the complexes was determined to be 39–42 nm. The powder X-ray and SEM coupled with energy dispersive X-ray (EDX) studies revealed the presence of the respective nano-sized metal oxides. The kinetic parameters of the decomposition of the complexes were calculated using the Coats-Redfern equation. 相似文献
9.
We report here the low temperature emission spectra in the heterometal dinuclear 3d-4f assembled molecular system [(acac) 2Cr III(μ-ox)Ln III(HBpz 3) 2] (Cr(ox)Ln:acac −=acetylacetonate, ox 2−=oxalate, HBpz 3−=hydrotris(pyrazol-1-yl)borate; Ln=La, Nd, Ho, Er , Tm and Yb) in comparison with those of Na[Cr(acac) 2(ox)] and [(HBpz 3) 2Ln(μ-ox)Ln(HBpz 3) 2](Ln=Nd and Er). From 10 to 150 K the Cr(ox)Ln complexes show a broad emission band around 800 nm from the 2E state of Cr(III) moiety. At room temperature no 2E- 4A 2 emission was observed in the Cr(ox)Ln except for the La and Lu complexes. On warming from 10 to 300 K rapid quenching of the 2E- 4A 2 emission of Cr(III) is suggested to result from the energy transfer from Cr to Ln in the Cr(ox)Ln. The excitation spectra and the life-time were also measured with monitoring the 4f-4f emission peaks of the Cr(ox)Yb complex. 相似文献
10.
Six crimson samarium (III) complexes based on β-ketone carboxylic acid and ancillary ligands were synthesized by adopting the grinding technique. All synthesized complexes were investigated via elemental analysis, infrared, UV–Vis, NMR, TG/DTG and photoluminescence studies. Optical properties of these photostimulated samarium (III) complexes exhibit reddish-orange luminescence due to 4G5/2?→?6H7/2 electronic transition at 606 nm of samarium (III) ions. Further, energy bandgap, color purity, CIE color coordinates, CCT and quantum yield of all complexes were determined accurately. Replacement of water molecules by ancillary ligands enriched these complexes (S2-S6) with decay time, quantum yield, luminescence, energy bandgap and biological properties than parent complex (S1). Interestingly, these efficient properties of complexes may find their applications in optoelectronics and lighting systems. In addition to these, the antioxidant and antimicrobial assays were also investigated to explore the applications in biological assays. 相似文献
11.
Three kinds of europium complexes; Eu(phen) 2Cl 3(H 2O) 2, Eu(DN-bpy)phenCl 3(H 2O) 2 and Eu(DB-bpy)phenCl 3(H 2O) 2 (phen: 1,10-phenanthroline, DN-bpy: 4,4′-Dinonyl-2,2′-dipyridyl, DB-bpy: 4,4′-Di- tert-butyl-2,2′-dipyridyl) were prepared and then incorporated into polymethyl methacrylate (PMMA) matrix with different molar ratios of CO groups/Eu 3+ ions. The final solid composites were formed by a self-assembly process among Eu 3+ ion, the ligands and PMMA during the solvent evaporation process, and then the ligands re-coordinate to Eu(III). It was found that the ligands affect not only the emission properties of the pure complexes, but also the miscibility of the complexes and PMMA. More than one kind of symmetric sites of Eu 3+ ions were formed in the composites due to the coordination of CO in PMMA to Eu 3+ ions. The micro-environments of Eu(III) in the composites were changed with the compositions and the ligands, leading to the change in the crystalline structure, and consequently, the emission characteristics. 相似文献
12.
The coordination geometries, electronic features, metal ion affinities, entropies, and the energetics of Li +, Na +, K +, Be 2+, Mg 2+, and Ca 2+ metal cations with different possible conformations of cysteine complexes were studied. The complexes were optimized using density functional theory (B3LYP) and second order Moller–Plesset Perturbation (MP2) theory methods using 6‐311 + +G** basis set. The interactions of the metal cations at different nucleophilic sites of cysteine conformations were considered after a careful selection among several binding sites. All the metal cations coordinate with cysteine in a tridentate manner and also the most preferred position for the interaction. It is found that, the overall structural parameters of cysteine are not altered by metal ion substitution, but, the metal ion‐binding site has undergone a noticeable change. All the complexes were characterized by an electrostatic interaction between ligand and metal ions that appears slightly more pronounced for lithium and beryllium metal complexes. The metal ion affinity (MIA) and basis set superposition error (BSSE) corrected interaction energy were also computed for all the complexes. The effect of metal cations on the infrared (IR) stretching vibrational modes of amino N? H bond, side chain thiol group S? H bond, hydroxyl O? H bond, and Carbonyl C?O bond in cysteine molecules have also been studied. The nature of the metal ion‐ligand bond and the coordination properties were examined using natural bond order (NBO) at bond critical point (electron density and their Laplacian of electron density) through Atoms in Molecules (AIM) analyses. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
13.
We studied sensitization of Eu(III) and Tb(III) ions by molecules of 1,10-phenanthroline and 2,2-bipyridil in D 2O and d 6-ethanol and the influence of Nd(III), Pr(III), Sm(III), Gd(III), and Ho(III) ions on the luminescence intensity I lum and lifetime τ lum of Eu(III) and Tb(III) in solutions. The stability constants of complexes of Eu(III) and Gd(III) with 2,2′-bipyridil are measured by spectrophotometric and luminescence methods. It is shown that luminescence of Eu(III) is quenched by Gd(III) ions at the ion concentration equal to 10 ?2–10 ?1 M, which is caused by competing between these ions for a sensitizer. At the concentration of Ln(III) ions equal to 10 ?6?10 ?3 M, the sensitized luminescence of Eu(III) and Tb(III) was quenched and τ lum decreased in the presence of Nd(III) ions, whereas in the presence of Gd(III) the luminescence intensity increased. It is proved that a bridge that connects the two ions upon energy transfer is formed by hydroxyl groups. The intensity of luminescence of Eu(III) and Tb(III) in aqueous solutions and its lifetime decreased in the presence of hydroxyl groups, while upon addition of Gd(III) to these solutions these quantities were restored. We also found that the addition of Gd(III) to deoxygenated ethanol solutions of 2,2′-bipyridil and Eu(III) slows down photochemical and thermal reactions between bipyridil and Eu(III), resulting in the increase in the luminescence intensity of Eu(III). 相似文献
14.
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·(NO 3) 2]·NO 3. 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 × 10 5 M −1 through fluorescence titration data. 相似文献
15.
Luminescence properties of lanthanide(III) ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy and Tm) were investigated by measuring the excitation and emission spectra, and emission lifetimes in H 2O and D 2O solutions of 3 moll ?1 K 2CO 3, where anionic tetra-carbonate complexes, [Ln(CO 3) 4] 5- were the predominant species. Electronic transitions of the carbonato complex corresponding to both the excitation and emission spectra were assigned from the energy level diagrams of Ln(III) and compared with those of the aqua ion. Enhancement of emission intensity of the complex was observed at particular excitation transitions of Eu(III), Gd(III) and Tb(III), and at particular emission transitions of Sm(III), Eu(III), Dy(III) and Tm(III). The enhancement at the emission transition was estimated quantitatively as a branching ratio from the lowest emitting state of Ln(III), and discussed in terms of hypersensitivity. Emission lifetimes of the carbonato complexes were all longer than those of aqua ions in H 2O solution, while the lifetimes of the complexes for Eu(III) and Tb(III) shorter than those in D 2O solution. The difference in non-radiative decay constants for the excited complex in H 2O and D 2O solutions was found to be proportional to an exponential of the energy gap of Ln(III). The lifetime ratio between the H 2O and D 2O solutions showed the order of Sm > Dy > Eu > Tb, corresponding to the opposite order of the energy gap. These were discussed in terms of an energy gap law, i.e. a relationship between the energy gap of Ln(III) and vibration energies of the ligand or water molecules. 相似文献
16.
A novel Aryl amide ligand H 2L and its eight complexes, [LnH 2L(NO 3) 2·H 2O]NO 3 [Ln=Sm(III), Er(III), Tb(III), Dy(III), La(III), Gd(III), Nd(III), and Pr(III)], are presented. The ligand and complexes were synthesized and characterized based on elemental analyses, molar conductance, IR, 1H and 13C-NMR, UV–VIS., and TGA studies. The conductivity data show a 1:1 electrolytic nature with a general formula [LnH 2L(NO 3) 2·2H 2O]NO 3 The IR spectra reveal coordination of the ligand through the azomethine nitrogen and the phenolic hydroxyl of the ligand to the lanthanide ion. The coordinated nitrate ions behave in a bidentate fashion. The thermal decomposition studies indicate the presence of two water molecules in the inner coordination sphere. Under the excitation at 319 nm, the luminescence emission properties for Sm, Tb, and Dy complexes are observed. These observations show that the ligand favors energy transfers to the emitting energy level of these lanthanide ions. Furthermore, the antioxidant activity of the ligand and its Ln(III) complexes was determined by DPPH radical scavenging method, which indicates that the Ln(III) complexes exhibit more effective antioxidant activity than the ligand alone. 相似文献
17.
A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized
by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity,
coordination titration analysis, IR, TG-DTA, 1HNMR and UV spectra. The composition of these complexes, were RE 2(ClO 4) 6·(L) 5·nH 2O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C 10H 7SOC 3H 6SOC 10H 7). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand
was benefited for transferring the energy from ligand to the excitation state energy level ( 5D 0) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between
the average triplet state energy level of ligand and the excited state ( 5D 4) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the
relationship between fluorescence lifetime and fluorescence intensity were also discussed. 相似文献
18.
In continuation of our studies on the complexes of lanthanide(III) ions with N-donor ligands 1,2, especially those of 1,10-phenanthroline (phen) 3,4, we wish to report the proton N.M.R. spectra of several lanthanide(III) complexes of phen in aqueous (D 2O) solution at 330 K. Table 1 contains the observed chemical shifts of the four types of protons in phen relative to the methyl resonance of the internal standard 2-methyl-2-propanol. For comparison, the spectrum of an authentic sample of Nd(phen) 2Cl 3.2H 2O complex prepared by the method of Sinha 5 was recorded and the spectrum found to be virtually indistinguishable from that obtained by mixing the individual components in the proper ratio. 相似文献
19.
The reaction of Ln(ClO 4) 3· nH 2O with triphenylphosphine oxide (TPPO) in methanol has led to the formation of [Ln(ClO 4) 2(tppo) 4]ClO 4·MeOH (Ln = Nd, Eu, Gd, Dy, Yb), in which the perchlorate anion acts as a symmetric bidentate. The emission spectra of Eu(III)-TPPO complexes, showing enhancement in the intensity due to the phenyl group, indicate an isotropic electron distribution for the nitrato complex [Eu(NO 3) 3(tppo) 2(EtOH)]. 151Eu and 155Gd M?ssbauer spectra of the TPPO complexes also lead to the same conclusion. 相似文献
20.
A novel ligand with double sulfinyl groups, bis(benzylsulfinyl)methane, was synthesized by a new method and its two lanthanide
(III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis,
IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL 2.5(ClO 4) 3·3H 2O (RE = Tb (III), Dy (III), L = C 6H 5CH 2SOCH 2SOCH 2C 6H 5). The FT-IR results revealed that the perchlorate group was bonded with the lanthanide ion by the oxygen atoms, and the coordination
was bidentate. The fluorescent spectra illustrated that both the Tb (III) and Dy (III) complexes displayed characteristic
fluorescence in solid state, especially for the Tb (III) complex, the peak of 5D 4 → 7 F 5 of the Tb (III) ion in 544 nm was stronger than that of others. It indicated that the Tb (III) complex could emit purer green
fluorescence. By analysis fluorescence and phosphorescence spectra, it was found that the ligand had the advantage to absorb
energy and transfer it to the Tb (III) and Dy (III) ions. The phosphorescence spectra and fluorescence lifetimes of the complexes
were also measured. 相似文献
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