Search

Research has been conducted on the heterodinuclear bis(mu-hydroxo)chromium(III)nickel(II) complexes. The preparation and synthesis of these complexes have been carried out and the structures and magneto-structural relationship of the complexes with the modulated magnetic interactions between chromium(III) and nickel(II) ions are discussed.

The synthesis of a six-coordinate bis(Mu-oxo)dinickel(III) complex is reported.

X-ray crystallography of the synthesis of mu-alkoxo diiron(II) complex (Fe2(Me4-tpdp)(C6H5COO)(H2O))(BF4)(sub 2) dinuclear iron complex indicates that the complex crystallizes in the monoclinic space group P2(sub l)/n. The complex contains two different iron centers, one five-coordinated iron center with N3O2 donor set, and another six-coordinated iron center. The thermal stability of the complex depends upon electron donor ability and the steric bulkiness. Raman resonance spectra reveal two oxygen isotope susceptible bands in v(O-O) region.

The role of the nucleus raphe obscurus (NRO) in the formation of gastric ulcers was studied by injecting kainic acid to stimulate neurons in the NRO. Kainic acid stimulation of the neurons within the NRO resulted in gastric erosions within 24 hours. Stimulation of neurons outside the NRO boundaries did nor produce gastric erosions. Bilateral gastric branch vagotomies prevented the formation of gastric ulcers during kainic acid stimulation of the NRO confirming assumptions that vagal stimulation play a centrral role in the maintenance of gastric mucosal integrity.

The nickel(II) complex cis-(Ni isocyclam H2O 2)Cl2.2H2O was synthesized and characterized. The diaqua complex was prepared by the dissolution of cis-(Ni en isocyclam)Cl2.4H2O in water and subsequent adjustment of the pH by HCl. The single-crystal X-ray structure of the complex consists of two coordinated water molecules at the cis positions of the Ni(II)-N4O2 octahedron with the isocyclam coordinated to the Ni(II) ion in a folded manner. TG, DTA and DSC measurements on the complex revealed that thermal reaction involved deaquation-anation with the cis geometry maintained.

Three types of heteropolyvanadates, [(C2H5)(sub 4)N](sub 4)[PdV6O18], [(C2H5)(sub 4)[Cu2V8O24], and [(C6H5)(sub 4)P](sub 4)[Ni4V10O30(OH)(super 2)(H2O)(sub 6)] were synthesized through the reaction between the [VO3]- anion and metal template cations of Pd(II), Cu(II), and Ni(II). Structural studies of cyclic heteropolyoxovanadates have allowed gaining insight into the metal template effect on the formation of the cyclic polyoxovanadate species in acetonitrile.

Pan, Yan, Takahiro Iwamoto, Akira Uehara, Tomoe Y. Nakamura, Issei Imanaga, and Munekazu Shigekawa. Physiological functions of the regulatory domains of the cardiac [Na.sup.+]/[Ca.sup.2+] exchanger NCX1. Am J Physiol Cell Physiol 279: C393-C402, 2000.--Physiological functions of the intracellular regulatory domains of the [Na.sup.+]/ [Ca.sup.2+] exchanger NCX1 were studied by examining [Ca.sup.2+] handling in CCL39 cells expressing a low-affinity [Ca.sup.2+] regulatory site mutant (D447V/D498I), an exchanger inhibitory peptide (XIP) region mutant displaying no [Na.sup.+] inactivation (XIP-4YW), or a mutant lacking most of the central cytoplasmic loop ([Delta]246-672). We found that D447V/D498I was unable to efficiently extrude [Ca.sup.2+] from the cytoplasm, particularly during a small rise in intracellular [Ca.sup.2+] concentration induced by the physiological agonist [Alpha]-thrombin or thapsigargin. The same mutant took up [Ca.sup.2+] much less efficiently than the wild-type NCX1 in [Na.sup.+]-free medium when transfectants were not loaded with [Na.sup.+], although it appeared to take up [Ca.sup.2+] normally in transfectants preloaded with [Na.sup.+]. XIP-4YW and, to a lesser extent, [Delta]246-672, but not NCX1 and D447V/D498I, markedly accelerated the loss of viability of [Na.sup.+]-loaded transfectants. Furthermore, XIP-4YW was not activated by phorbol ester, whereas XIP-4YW and D447V/ D498I were resistant to inhibition by ATP depletion. The results suggest that these regulatory domains play important roles in the physiological and pathological [Ca.sup.2+] handling by NCX1, as well as in the regulation of NCX1 by protein kinase C or ATP depletion. calcium flux; sodium loading; cell viability; cell death; protein kinase C

Research is presented demonstrating the production of bis(mu-oxo)dicopper(III) species, from the tetradentate Me2-tpa ligand which has donors of aromatic nitrogen, which can be converted reversibly to copper(I) species.

Scientists have established that the ethanolysis of urea is catalyzed by the carboxylate-bridged dinickel(II) complexes (R = CH3- or HO-) containing Me4-tpdp. According to X-ray crystal structure analysis the carboxylate-bridged dinickel(II) complexes between two Ni ions are used in the catalysis process. The Mu-acetato Ni(II) complexes contain a Ni ion which can bind to urea and a Ni ion which activates ethanol by coordination. Further research is required to establish how carbon dioxide is used in the reconstitution of apo-urease with Ni(II) ions.

The role of the protein hemerythrin (Hr) in dioxygen transport was determined by examining the structure and activation of a novel mu-peroxo diiron complex, [Fe2(Ph-bimp)(C6H5COO)(O2)](BF4)2.2CH3CN.C2H5OC2H5.H2O. X-ray crystallography of the crystal revealed higher thermal stability toward irreversible oxidation than previously reported mu-peroxo diiron complexes. The molecular structure of this complex is presented.