Paramagnetic liquid crystal complex of iron(III) with a schiff base

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, p. 1931, August, 1989.     

Structure of a new schiff base cobalt(III) complex with antibacterial activity

A new Schiff base cobalt(III) complex with the formula [CoL¹L²(N₃)]·NO₃ (L¹ is 2-[1-(2-phenylaminoethylimino)ethyl]phenolate, L² is N-phenylethane-1,2-diamine) is prepared and characterized by physicochemical methods and single crystal X-ray determination. The complex crystallizes in the triclinic system space group P-1, with a = 8.504(2) Å, b = 14.973(3) Å, c = 20.676(4) Å, α = 100.021(3)°, β = 90.005(3)°, γ = 103.084(2)°, V = 2523.0(9) ų, Z = 4, R ₁ = 0.0732, and wR ₂ = 0.1182. Single crystal X-ray diffraction analysis reveals that the complex contains two mononuclear [CoL¹L²(N₃)]⁺ cations and two nitrate anions. The Co atom is six-coordinated in an octahedral geometry. The ligands and the cobalt(III) complex are screened in vitro for their antibacterial activity against Bacillus subtillis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aereuguinosa.     

Effects of polarity and temperature on photoluminescence of a europium(III) chelate

The relative photoluminescence yield for (1,10-phenanthroline)europium(III) tris-thenoyltrinuoroacetonate (Eu(tta)₃Phen). an efficient enhancer of chemiluminescence, has been measured under the conditions (temperatures and solvents) specific for the oxidation of hydrocarbons. The yield is independent of viscosity and the presence of a heavy atom in the solvent, but the higher the polarity of the medium, the more the yield decreases as the temperature increases. The effect is interpreted as an acceleration of radiationless deactivation occurringvia the mechanism of electron transfer from a ligand to the excited Eu³⁺ ion.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1686–1690, July, 1996.     

Syntheses of polyfluorophenylcobalt(III) schiff base complexes using organothallium reagents

The complexes RCo(acacen) [R = C₆F₅, p-HC₆F₄, or o-HC₆F₄; H₂acacen = N,N′-ethylenebis(acetylacetonimine)] and RCo(salen) [R = C₆F₅ or p-HC₆F₄; H₂salen = N,N′-ethylenebis(salicylaldimine)] have been prepared by reaction between Co(acacen) or Co(salen) and the appropriate bromobis(polyfluorophenyl)thallium(III) compounds, and have been isolated as pyridinates. Spectroscopic evidence for formation of C₆F₅Co(salophen) [H₂salophen = _N,N′-o-phenylenebis(salicylaldimine)] has also been obtained. The reactivity of the thallium compounds increased in the sequence Ph₂TlBr ? (o-HC₆F₄)2TlBr < (p-HC₆F₄)₂TlBr < (C₆F₅)₂TlBr, and of the cobalt complexes in the sequence Co(salophen) < Co(salen) < Co(acacen). Possible mechanisms are discussed.     

A europium(III) chelate as an efficient time-gated luminescent probe for nitric oxide

The first Eu(3+) chelate-based luminescent probe specific for nitric oxide (NO) has been designed and synthesized for highly sensitive and selective time-gated luminescence detection of NO. Based on the probe, a time-gated luminescence imaging technique was developed for imaging the endogenous NO production in living plant cells/tissues.     

Method of labeling antibodies with europium(III)-4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-di-carboxylic acid chelate.

On the basis of Eu(III)-4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-di-carboxylic acid chelate (BCPDA) that was synthesized and characterized for time-resolved fluoroimmunoassay (TRFIA), Donkey anti-hepatitis B surface (anti-HBs) was labeled with BCPDA-Eu3+. Coomassie Brilliant Blue was used to determine the protein concentration and radio immunoassay (RIA) for detecting the biological activity in the labeled protein. Optimal conditions for the protein labeling were obtained by monitoring the reaction. Results suggested that the protein could be labeled with BCPDA under relatively moderate conditions. As a practical application, a protein-BCPDA-Eu3+ chelate was obtained by using BCPDA-protein that reacted with EuCl3 under certain conditions. Some properties of BCPDA and protein-BCPDA-Eu3+, such as absorption spectrum, emission spectrum and fluorescence lifetime, were discussed. The detection limit and the linear working range of the established method were also investigated.     

Transition metal(II) ions with dinegative tetradentate schiff base

Some new coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), obtained from the interaction of metal acetate with dipotassium salt of N,N’-di(carboxyethylidene)terephthalaldehydediimine (K₂SB) are described. The products, which have been characterized by elemental analyses, magnetic measurements, thermogravimetric analyses, electronic and infrared spectral studies, have composition, [M(SB)(H₂O)₂]_n. These colored coordination polymers are non-hygroscopic and quite stable at room temperature. On the basis of analytical data and IR studies, a 1:1 metal to ligand stoichiometry has been suggested to these coordination polymers. The IR studies have also revealed that ligands are coordinated to metal ion through carboxy oxygen and azomethine nitrogen. All the studies suggested tetradentate nature of the ligand with octahedral symmetry of the coordination polymers. All the coordination polymers are insoluble in acetone, ethanol, chloroform, methanol, benzene, DMF and DMSO. The thermal decomposition of the coordination polymers is studied and indicates that not only the coordinated water is lost but also that the decomposition of the ligand from the coordination polymers is necessary to interpret the successive mass loss.     

A triboluminescent europium(III) complex

The crystal structure of (4,4′‐di­methyl‐2,2′‐bipyridyl)­tris­[3,3,3‐tri­fluoro‐1‐(2‐thenoyl)propan‐2‐onato]­europium(III), or more commonly (4,4′‐dimethyl‐2,2′‐bipyridyl)tris(2‐thenoyltrifluoro­acetonato)europium(III), [Eu(C₈H₄F₃O₂S)₃(C₁₂H₁₂N₂)], has been determined. Crystals of the complex emit vivid red light when scratched or fractured. This triboluminescent activity seems to correlate with the non‐centrosymmetric crystal structure and disorder of the thienyl rings and CF₃ groups which is present here and in similar compounds. While modeling the thienyl‐ring disorder, it was noted that the bond angle at the C atom replaced by S is a sensitive sign of even small rotational ring disorder. The coordination geometry of the Eu^III ion can be described as square antiprismatic, with coordination by the six O atoms of the three chelating β‐diketonate ligands and the two N atoms of the neutral bipyridyl ligand.     

Biologically active organotin(IV) schiff base complexes

Organotin(IV) complexes with the general formulae R₃ML [R: alkyl (Et, Ph and Bz), M: Sn and L: 1,3-bis(2- hydroxybenzylidene)thiourea were synthesized. The newly synthesized schiff base and its complexes were characterized by elemental analysis, melting point, molecular weight determination, IR and NMR [¹H, ¹³C and ¹¹⁹Sn] spectral methods. In the light of these techniques, a tetrahedral geometry around the tin atom is proposed for the synthesized complexes. The experimental data have been compared with those in the literature which were found to coincide very well with the assigned structures. The ligands and their tin(IV) complexes were screened in vitro for their antibacterial activities. It was found that they possessed significant antibacterial activity and the effect of Ph₃SnL was possibly superior to those of Et₃SnL, Bz₃SnL and ligand. These findings add new insights onto the synthesis of antibacterial drugs as the synthesized compounds showed promising antimicrobial activity.     

Intramolecular energy transfer in a one-dimensional europium tetracyanoplatinate

The one-dimensional, polymeric compound (C15H11N3)Eu(H2O)2(NO3)(Pt(CN)4).CH3CN (1) has been shown to display an efficient donor-acceptor intramolecular energy-transfer (IET) process where ligand donors transfer energy to the Eu (III) acceptor. Single-crystal X-ray diffraction has been used to investigate the structural features of this compound in order to help understand the observed IET process. Crystallographic data: 1, monoclinic, space group P2(1)/c, a = 12.835(1) A, b = 15.239(1) A, c = 13.751(2) A, beta = 105.594(9) degrees , V = 2590.8(5) A(3), and Z = 4 (T = 290 K).     

Fluorescence of europium(III) in a flouride glass containing zirconium

Europium(III) incorporated in a new zirconium barium flouride glass shows 14 luminescent transitions (at 300 K) from ⁵D_J (J= 0,1,2,3) to ⁷F_J (_J = 0,1,2,3,4) which are compared with Judd-Ofelt parameters for induced electric dipolar radiation, as well as for calculated magnetic dipolar transition probabilities.     

Charge-transfer excited state in tris(acetylacetonato) europium(III)

The extremely low efficiency of the intramolecular energy transfer process in europium acetylacetonate compared with the corresponding terbium acetylacetonate is attributed to the presence of a charge-transfer excited state lying below the ligand singlet states. This is supported by the anomalous absorption spectrum of the Eu³⁺ complex and the effects of added anions in other ligand systems.     

News analytical reagents for europium(III)

The complexant reactions of 2'-hydroxychalcones with europium(III) are studied by the spectrophotometric method. The apparent formation constants are evaluated using a simple graphical linear method. The sequence of these constant values is explained and compared with aluminium(III) complexant reactions.     

Mechanism of photostabilization of a europium(III) complex in polyethylene with Tinuvin-622

The mechanism by which selected photostabilizing sterically hindered amines (Tinuvin-622, Diacetam-5, Polyacetam-81) affect the photostability of the complex Eu(Phen)₂(NO₃)₃ in low-density polyethylene was studied by the luminescence, ESR, and ¹H NMR spectroscopy.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1543–1546.Original Russian Text Copyright © 2004 by Mirochnik, Zhikhareva, Karasev, Kuryavyi.     

Photokinetics of gas phase europium(III) chelated with hexafluoroacetylacetonate

The europium chelate salt, triethylammonium tetrakis-hexafluoroacetylacetone europium(III), was evaporated into the gas phase and the luminescence properties of the gas phase material were examined. The rate of decay of luminescence of the gas phase europium chelate was observed to increase with temperature. An activation energy of 2650 cm⁻¹ was measured for the barrier to non-radiative decay from the ⁵D₀ state. The quantum yield for formation of the ⁵D₀ state showed a slight temperature dependence at temperatures above 220°C.     

Interaction features of cerium (III) and europium (III) acetate and pivalate with monoethanolamine

The composition of mixed-ligand complexes of cerium (III) and europium (III) acetates and pivalates with monoethanolamine (MEA) depends on the synthesis conditions and the nature of carboxylate ligand. We prepared solid complexes [Ln(Piv)₃(MEA) _x ], where Ln = Ce, Eu; HPiv-2,2-dimethylpropionic (pivalic) acid; x = 1, 1.5, and gel-like hydroxocomplexes [Ln(Carb) _{n − x − y} ,(NO₃) _x (OH) _y (MEA) _w (H₂O) _z ], where Ln = Ce, n = 4; Ln = Eu, n = 3; HCarb is acetic acid (HAcet) or HPiv. The values of the coefficients x, y, w, and z depend on the synthesis conditions and heat treatment. Prepared compounds were characterized by IR and ¹H NMR spectroscopies, elemental and thermal analyses, and MALDI-MS. The ESI-MS method was used to characterize the processes occurring in the solutions.