Synthesis, spectroscopic and thermal studies of the copper(II) aspartame chloride complex

Aspartame adduct of copper(II) chloride Cu(Asp)₂Cl₂·2H₂O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions.     

氟化镁锶中铕和铽的电荷迁移及其平衡解析

在氩气氛中，合成了SrMgF4：xEu，yTb复合组化物磷光体．该体系中Eu3 和Eu2 共存．随共掺入Tb浓度的增加，Eu3 的荧光发射强度降低，Eu2 的发光增强；并且Eu2 的ESR信号增强．认为Eu3 和Tb3 之间存在电荷迁移．即Eu3 ＋Tb3 →Eu2 ＋Tb4 .通过半定量手段研究了这一电荷迁移反应的平衡常数     

A new method for the generation of stable phenoxyl radicals by the reaction of [(Me3Si)2N]2E (E = Ge,Sn) with sterically hindered phenols

An unusual reaction of diaminogermylene and diaminostannylene with sterically hindered phenols which leads to the formation of stable phenoxyl radicals in high concentrations was found. The reaction mechanism was proposed. Amides [(Me₃Si)₂N]₂E (E = Ge, Sn) were investigated electrochemically.     

配位聚合载体化催化剂ESR研究进展

本文概述了配位聚合载体化催化剂的ESR研究进展,介绍了载体研究、活性中心研究及计算机模拟技术研究方面的发展概况.     

ESR study of electron interaction in a Tc/Al2O3 system

An investigation was made into the nature of paramagnetic centers in a Tc/Al₂O₃ system under varying conditions as to heat treatment and technetium content, and in O₂ and CO adsorption environments. It was found that in the case of reduction at 573 K Tc²⁺ ions and, conceivably, other ionic forms developed and stabilized on the carrier surface. After reduction at 973 K two types of electron center appeared, whose concentration increased as reduction was prolonged. Signals were observed in the low fields (3–20 mT) of the ESR spectra having g₁ 13.5 and g₂>30, which could be assigned to free charge carriers in a cluster of metal atoms or ions. Adsorption of O₂ at 300 K caused O ₂ ^– ion radicals to form on the surface of the reduced Tc/Al₂O₃ samples, both electron centers and technetium ions constituting the electron donors. In the case of CO adsorption paramagnetic (CO) ₂ ^– particles appeared on the Tc/Al₂O₃ samples after prolonged exposure. On reaction with O₂ two types of O ₂ ^– ion-radical with differing thermal stability were formed.Institute of Physical Chemistry, Russian Academy of Sciences, Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 1972–1978, September, 1992.     

r,r′-联吡啶桥联Cu,Rh配合物的合成、晶体结构和ESR谱

合成了r,r’-联吡啶为桥的异双核配合物[(H_2O)Cu(dien)(μ-r,r’-bpy)Rh(NH_3)_5](ClO_4)_5·H_2O.研究了单晶结构和ESR谱.晶体属正交晶系,空间群Pbca,晶胞参数:a=14.425(1),b=29.589(2),c=16.893(6)A,Z=8.偏离因子R=0.065.分子中Cu~(2+)和Rh~(3+)分别取五配位的四方锥和六配位的八面体构型,联吡啶桥的2个吡啶面夹角为51°.依据ESR谱计算了3配合物中Cu~(2+)的键参数并讨论了Cu~(2+)的成键性质.     

STUDIES OF ELECTRON SPIN RESONANCE ON BILIRUBIN FREE RADICALS

The nature of ESR signals derived from bilirubin-Ⅸα has been studied by focusing onthe samples treated with free radical generating and inhibiting systems, i.e. X-XOD, Fe/EDTA, SOD, mannitol/ascorbate, CO, KCN, etc. In all the cases, the stable signals comprisethose originated from semiquinone radical (g = 2.0012) and superoxide free radical (g_∥=2.041, g_⊥= 2.0040). The superoxide is shown binding with certain metal ions chelated bybilirubin. The free radical scavengers are able to destroy these radicals. The kinetic curveof the regeneration of bilirubin radicals has been determined and the reaction follows azero order mechanism. It is likely that both the physiological and toxic actions of bilirubinare related to the characters of its free radicals. Bilirubin is discussed as "active oxygensink" in mammalians.     

Molecular structure of mixed adsorption layers surfactant—polymer at a liquid—liquid interface

Isotherms of the binding of dodecyl sulfate anions (DDS^–)and Na⁺ counterions during their coadsorption with a nonionic polymer. proxanol (PR). at the interface of dodecane-water emulsions have been measured by conductometry and Na-selective potentiometry. The adsorption of DDS^– and PR is concurrent. The affinity constant of PR to the interface determined by the Langmuir model decreases as the concentration of PR increases, and the surface concentration of DDS^– tends to a nonzero limiting value at high concentrations of PR. The surface (_o) and electrokinetic () potentials at the interface have been determined at various polymer concentrations by the spin probe and electrophoresis methods. The average dielectric permeability and density of polymer segments in We adsorption layer have been determined by ESR. The lower boundary of the hydrodynamic thickness of the polymer adsorption layer at the interface has been estimated from the dependences of _o and on the ionic strength.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1653–1661, July, 1996.     

过硫酸盐和N,N,N′,N′-四甲基乙二胺体系引发烯类聚合机理的研究

<正> 过硫酸盐和N,N,N′,N′-四甲基乙二胺(TMEDA)体系用作烯类聚合的引发剂已有报道。本文报道该引发体系的反应机理。1.实验方法     

Synthesis and structural, spectroscopic and magnetic studies of two new polymorphs of Mn(SeO3)·H2O

Two new manganese(II) selenite polymorphs with formula Mn(SeO₃)·H₂O have been synthesized by slow evaporation from an aqueous solution. The crystal structure of both compounds (1) and (2) have been solved from X-ray diffraction data. The structure of (1) was determined from single-crystal X-ray diffraction techniques. The compound crystallizes in the Ama2 space group, with a=5.817(1), b=13.449(3), and Z=4. The structure of (2) has been solved from X-ray powder diffraction data. This phase crystallizes in the P2₁/n space group with unit-cell parameters of a=4.921(3), b=13.121(7), , β=90.03(2)° and Z=4. Both polymorphs exhibit a layered structure formed by isolated sheets of MnO₆ octahedra and (SeO₃)²⁻ trigonal pyramids in the (010) plane. These layers, which contain one manganese and selenium atom crystallographically independent, are formed by octahedra linked between them through the selenite oxoanions. The difference of both compounds consists in the stacking of the layers along the b-axis. The IR spectra show the characteristic bands of the selenite anion. Studies of luminescence performed at 6 K and diffuse reflectance spectroscopy have been carried out for both phases. The Dq and Racah (B and C) parameters, from luminescence and diffuse reflectance spectroscopy, are Dq=705, B=750, for (1) and Dq=720, B=745, for (2). The ESR spectra of both compounds are isotropic with g-values of 1.99(1). Magnetic measurements indicate the presence of antiferromagnetic couplings in both phases. The J-exchange parameters have been estimated by fitting the experimental magnetic data to a model for square-planar lattice. The values obtained are J/k=-0.83, −0.91 K and J^′/k=-0.97, −1.20 K, for polymorphs (1) and (2), respectively.