Synthesis and relaxivity of Gd(III), Fe(III) and Mn(II) complexes with dihydropyridine derivative of diethylenetriaminepentaacetic acid

A novel ligand of DTPA-dihydropyridine derivative was synthesized by reaction of DTPA-dianhydride with 4-aniline-1,4-dihydropyridine. Its complexes of gadolinium, manganese and iron were prepared. Their spin-lattice relaxivities (T₁) were investigated. The results show that the NMR T₁ relaxivitives (R₁) for complexes of Fe(III), Mn(II) are less than that of Gd(III) complex, which has a high relaxivity (R₁) on the surrounding water protons, indicating that the Gd(III) complex possesses the precondition to be contrast agents for magnetic resonance imaging.     

Synthesis of self‐healing supramolecular rubbers from fatty acid derivatives,diethylene triamine,and urea

We describe the synthesis of supramolecular self‐healing elastomers from vegetable oil fatty acid derivatives, diethylene triamine, and urea. Our strategy to obtain materials that are self‐healing but do not flow relies on the use of a wide molecular distribution of randomly branched oligomers equipped with self‐complementary and complementary hydrogen bonding groups. We prepared such oligomers with a two steps procedure. In the first step, diethylene triamine was condensed with dimer acids. In the second step, the oligomers obtained were allowed to react with urea. The molecules were characterized by NMR and IR spectroscopies and Monte‐Carlo simulations were used to analyze the molecular size distribution. The sensitivity to small variations of the experimental conditions has been examined and the robustness of the synthetic procedure optimized. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7925–7936, 2008     

Synthesis,characterization and reactivity of a neutral antimony(III) complex

Pincer complexes are widely used in organometallic and coordination chemistry. The role of antimony as a central donor atom in pincer ligands has been extensively explored in recent years. Although phenylenediamine derived PXP (X = B, Al, C, Si, Ge, Sn, N) type ligands exhibit diverse reactivity, analogues species based on antimony have been reported less frequently. Herein, we report a new PSbP complex and evaluate its reactivity. These species will broaden the family of phenylenediamine derived pincer complexes.     

Synthesis,characterization, and antioxidant activity of a new Gd(III) complex

A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties.     

Pulse radiolysis study of the reactivity of metal complexes of DTPA /diethylene triamine pentaacetic acid/ with OH radicals in aqueous solutions

Using the pulse radiolysis competition kinetic technique, OH radical rate constants with 12 metal DTPA complexes were determined in neutral aerated aqueous solutions. They are in the range of /1.3–5.9/×10⁹ dm³ mol^–1s^–1. To a first approximation, the rate constant was found to decrease linearly with an increase in the field strength of the metal ion (q/r²).     

Stability and thermodynamics of La(III)-, Pr(III)-, Nd(III)-, Gd(III)- and Eu(III)-p-nitrobenzaldehyde thiosemicarbazone systems

Three complexes containing bidentate N-2,3-dimethylphenylglycine, (2,3-HDPG), N-2,4-dimethylphenylglycine, (2,4-HDPG) and N-2-ethylphenylglycine, (2-HEPG) acids have been prepared and characterized. These compounds have the general formula Zn(2,3-DPG)₂·2 H₂O, Zn(2,4-DPG)₂ and Zn(2-EPG)₂·2 H₂O, respectively. The structure of the complexes as inferred from their chemistries have been found to be compatible with the infrared spectral data. The thermal behaviour of these complexes has been studied from their TG, DTG and DSC diagrams obtained in a dynamic atmosphere of pure air. Heats of dehydration have been calculated from DSC curves.     

Spectrophotometric determination of the stability constant of the Eu(III)-murexide complex

The values of the stability constants of the Ca(II) and lanthanide(III) complexes of murexide reported in the literature were determined without proper correction for binding of buffer ions to the metal ion. The constants are best determined without a buffer present. Accurate values of conditional stability constants for the Eu(III)—murexide complex (relative standard deviation better than 3%), of the differential molar absorptivity of the Eu(III)—murexide complex with respect to murexide at 480 nm (relative standard deviation better than 0.5%) and of the molar absorptivity of murexide at 520 and at 506 nm (precision better than 0.4%) at pH 5.0 and 6.5 at 15, 25 and 35° are reported. The accuracy and precision of the concentration of metal ion solution determined by using these conditional stability constants are discussed.     

Luminescent and triboluminescent properties of europium(III) complex with cinnamic acid

An intensely emitting crystalline europium(III) complex with cinnamic acid [Eu(Cin)₃] _n and exhibiting triboluminescent properties is synthesized. It is established that the measured photo- and triboluminescence spectra are identical for the above polymeric non-centrosymmetric complex and are determined by the characteristic f-f luminescence of the europium(III) ion.     

Synthesis, opto-physics, and electroluminescence of cyclometalated iridium (III) complex with alkyltrifluorene picolinic acid

To improve the opto-physics, electroluminescence, and dispersibility of iridium (III) complexes in polymer light-emitting devices, we synthesized and characterized two red-emitting heteroleptic cyclometalated iridium (III) complexes of (Piq)₂Ir(Tfl-pic) and (Piq)₂Ir(Brfl-pic), in which Piq is 1-phenylisoquinoline, Tfl-pic and Brfl-pic are alkyltrifluorene- and dibromoalkylfluorene-containing picolinic acid derivatives bridged with alkoxy chain, respectively. Compared to (Piq)₂Ir(pic) and (Piq)₂Ir(Brfl-pic), (Piq)₂Ir(Tfl-pic) exhibited higher thermal stability, better dispersibility and excellent quantum efficiency. High-efficiency red emission with a maximum current efficiency of 6.28 cdA⁻¹ and a maximum EL peak at 608 nm was obtained in the (Piq)₂Ir(Tfl-pic)-doped devices using a blend of poly(9,9-dioctylfluorene) and 2-(4-biphenyl)-5-(4-tert -butylphenyl)-1,3,4-oxadiazole as a host matrix.     

Synthesis and luminescence properties of neutral Tm(III), Dy(III), and Gd(III) complexes with 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione and 1,10-phenanthroline

Neutral complexes of composition [LnL₃Phen], where Ln = Tm, Dy, and Gd, were synthesized by the reaction of LnCl₃ with heterocyclic diketone 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione (HL, 1) and 1,10-phenanthroline in an aqueous alcohol solution in the presence of NaOH. The composition of the complexes was proved by elemental analysis. Their optical and luminescence properties were studied.     

Synthesis of terbium(III) complex with a biscoumarin derivative and its immobilization in PMMA-based composite thin films with fluorescent properties

An amorphous complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methylene)]bis-(4-hydroxy-2H-1-benzopyran-2-one), Tb(H₂L)₃, was successfully synthesized and characterized. IR- and ¹H-NMR-spectroscopy were used to investigate the coordination of the ligand around the Tb(III) ion. Values for the quantum yield and the life time of the excited state of the complex were obtained. The complex was immobilized in transparent and flexible PMMA-based films by a simple casting technique. PMMA/chloroform solutions were used in synthetic procedures that resulted in both glass-supported and self-supporting nanocomposite films. The morphology of the films was studied by scanning electron microscopy, atomic force microscopy and transmission electron microscopy, showing the formation of crack-free films. The presence of the Tb(III) complex in the matrix was proven by the presence of characteristic bands in the IR spectra. Fluorescence microscopy and fluorescence spectroscopy demonstrated the promising optical properties of the films showing the characteristic emission bands of the Tb(III) ions. The longer life time of the excited state of the immobilized complex confirmed the protective role of the PMMA matrix on the optical properties of the complex. The composite films possessing optical properties have the potential for application as active components in optical devices.      

Synthesis,spectral, antimicrobial,and thermal properties of Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) gliclazide complexes

The complexation between the lanthanide metal ions Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) and gliclazide produced 1 : 1 molar ratio metal: gliclazide (Glz) complexes coordinated in a monodentate fashion via the OH group and having the general formulas [M(Glz)Cl₃(H₂O)]·xH₂O (M = Ce, Gd, Nd and x = 1, 3, 4, respectively) and [M(Glz)(H₂O)₄]Cl₃·yH₂O (M = Tb, Er and y = 1, 2, respectively). The structure of the synthesized lanthanide gliclazide complexes was assigned by IR, ¹HNMR, and UV-Vis spectroscopy. Thermal analysis and kinetic and thermodynamic parameters gave evidence for the thermal stability of the Glz complexes. The latter showed a significant antimicrobial effect against some bacteria and fungi.     

Extraction of Sm(III), Gd(III) and Ho(III) ions with picrolonic acid in methylisobutylketone

Summary Picrolonic acid (HPA) in methylisobutylketone (MIBK) (0.01 mol^. dm^-3) has been used for the extraction of lanthanide(III) ions such as Sm(III), Gd(III) and Ho(III) (Me) (~3^. 10^-6mol^. dm^-3) from pH 1-2 buffer solutions of 0.1 mol^. dm^-3(H⁺, Cl^-) ionic strength and quantitative extraction (>95%) was found at pH 2. Through slope analysis the composition of the organometallic adduct responsible for the extraction came out to be M(PA)₃. The conditional equilibrium constant values, log K_ex, were deduced to be 2.60±0.01, 2.09±0.01 and 1.44±0.03 for these lanthanide(III) ions, respectively. The metals in concentration up to ~2.5^. 10^-4mol^. dm^-3can be quantitatively extracted by the proposed system. Among the various anions, fluoride, oxalate and cyanide ions (~3.0^. 10^-4mol^. dm^-3) and, among the cations, Zn(II) Cu(II), Co(II) and Fe(III) reduced the lanthanide extraction. The extraction of various other metal ions at the optimized conditions of Me extraction for this series of lanthanide ions was also studied and high separation factors (10²-10³) were obtained showing the good selectivity of this extraction system.     

Synthesis,spectral, and thermal properties,and crystal structure of cobalt (III) complex derived from Imazameth

A novel metal–organic coordination compound [Co(Imazameth)₃]·0.5DMF·4H₂O (where Imazameth = (±)-2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H- imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid; DMF = N,N-dimethylformamide) has been prepared and characterized by spectral method (IR), elemental analysis, thermal gravimetric analysis (TGA), fluorescence properties, and single crystal X-ray diffraction techniques. It crystallizes in the trigonal system, space group R-3 and the asymmetric unit contains four water molecules. The four lattice water molecules and their symmetric equivalent form a slight distorted cubical water cluster through hydrogen bonds. The O···O bonds of the water cluster are in the range of (2.80(7)–2.99(2) Å), and O···O···O angles are in the range of (82.54°–101.38°). In the cubical water clusters, the six O(5) atoms of each cube are connected to six O(1) atoms of the six molecules (O(1)···O(5) = 2.77(1) Å) by hydrogen bonding, respectively. The Co atom is six-coordinated by six N atoms in distorted octahedron coordination geometry. Intramolecular N–H···O and intermolecular O–H···O hydrogen bonds result in the formation of a supermolecular crystal, in which they seem to be effective in the stabilization of the structure. The complex displays strong fluorescence property and good thermal stability.     

Synthesis,characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.     

Phosphinic derivative of DTPA conjugated to a G5 PAMAM dendrimer: an 17O and 1H relaxation study of its Gd(III) complex

A DTPA-based chelate containing one phosphinate group was conjugated to a generation 5 polyamidoamine (PAMAM) dendrimer via a benzylthiourea linkage. The Gd(III) complex of this novel conjugate has potential as a contrast agent for magnetic resonance imaging (MRI). The chelates bind Gd3+via three nitrogen atoms, four carboxylates and one phosphinate oxygen, and one water molecule completes the inner coordination sphere. The monomer Gd(III) chelates bearing nitrobenzyl and aminobenzyl groups ([Gd(DTTAP-bz-NO2)(H2O)]2- and [Gd(DTTAP-bz-NH2)(H2O)]2-) as well as the dendrimeric Gd(III) complex G5-(Gd(DTTAP))63) were studied by multiple-field, variable temperature 17O and 1H NMR. The rate of water exchange is faster than that of [Gd(DTPA)(H2O)]2- and very similar on the two monomeric complexes (8.9 and 8.3 x 10(6) s-1 for [Gd(DTTAP-bz-NO2)(H2O)]2- and [Gd(DTTAP-bz-NH2)(H2O)]2-, respectively), while it is decreased on the dendrimeric conjugate (5.0 x 10(6) s-1). The Gd(III) complex of the dendrimer conjugate has a relaxivity of 26.8 mM-1 s-1 at 37 degrees C and 0.47 T (corresponding to 1H Larmor frequency of 20 MHz). Given the contribution of the second sphere water molecules to the overall relaxivity, this value is slightly higher than those reported for similar size dendrimers. The experimental 17O and 1H NMR data were fitted to the Solomon-Bloembergen-Morgan equations extended with a contribution from second coordination sphere water molecules. The rotational dynamics of the dendrimeric conjugate was described in terms of global and local motions with the Lipari-Szabo approach.     

A novel terbium complex using oxadiazole derivative as a neutral ligand： Synthesis and properties

A novel terbium complex using 1,3,4-oxadiazole derivative as a neutral ligand was synthesized and characterized. Its thermal stability and photoluminescent properties were studied. The strong emission peaked at 546 nm with a full width at half maximum of 5 nm was observed in the pure terbium complex film under excitation of 328 nm light, which is attributed to the characteristic emission of terbium ion. The good thermal stability and intense sharp emission of this terbium complex display its potential application in electroluminescence devices.     

Synthesis and relaxivity of Gd(Ⅲ), Fe(Ⅲ) and Mn(Ⅱ)complexes with dihydropyridine derivative of diethylenetriaminepentaacetic acid

A novel ligand of DTPA-dihydropyridine derivative was synthesized by reaction of DTPA-dianhydride with 4-aniline-1,4-dihydropyridine. Its complexes of gadolinium, manganese and iron were prepared. Their spin-lattice relaxivities (T1) were investigated. The results show that the NMR T1 relaxivitives (R1) for complexes of Fe(Ⅲ), Mn(Ⅱ) are less than that of Gd(Ⅲ) complex,which has a high relaxivity (R1) on the surrounding water protons, indicating that the Gd(Ⅲ) complex possesses the precondition to be contrast agents for magnetic resonance imaging.     

甲基丙烯酸-8-羟基喹啉-镧配合物的合成及与DNA的作用

合成了配合物La(C4H6O2)2(hq)(C4H6O2=甲基丙烯酸,hq=8-羟基喹啉),通过元素分析、摩尔电导、红外光谱、紫外光谱和热重分析手段对产物进行表征。此外,采用紫外吸收光谱、荧光光谱,研究了配合物与鲱鱼精DNA之间的相互作用。结果显示配合物与鲱鱼精DNA作用的结合常数K=7.59×103L·mol-1,配合物与DNA的作用摩尔比为1∶1,作用模式为嵌插作用。