Robert G. Charles

Differential thermal analysis of divalent metal 8-hydroxyquinoline chelates

Abstract DTA curves were obtained for a number of anhydrous metal chelates derived from the important analytical reagent 8-hydroxyquinoline. The compounds were heated in an inert atmosphere to avoid interaction with oxygen or water vapor. The Cu, Pb, Zn, Ni and Co chelates melted without decomposition, under the conditions used, while the remainder of the compounds underwent partial decomposition upon melting. The order of increasing melting point is Pb Mg > Sr > Cd > Mn > Ba > Co > Ni > Zn > Pb > Cu.

RARE EARTH CHELATES DERIVED FROM 8-QUINOLINOL

Abstract The composition and heat stabilities of trivalent lanthanide oxinates prepared by homogeneous precipitation (urea hydrolysis in the presence of acetic acid) have been studied. The products contain acetate ion; and the molar ratio oxinate/metal is less than three. Polymeric structures are proposed for these materials, Heat stability in an inert atmosphere, as determined by thermogravimetric, thermomanometric and differential thermal analyses, decreases with increasing atomic weight of the metal.

Energy Transfer between p‐Benzoylbenzoate and Europium Ethylenediaminetetraacetate in Water Solution

Ultraviolet radiation absorbed by the p‐benzoylbenzoate (p‐BB−) ion in solution is transferred to an appreciable extent to the europium ethylenediaminetetraacetate (EuEDTA−) ion and is re‐emitted as the visible red fluorescence characteristic of Eu3+. Fluorescence intensity is greater in D2O than in water. The fluorescence is quenched by dissolved O2. Although evidence for mixed ligand complexes involving p‐BB− and EuEDTA− was obtained, fluorescence seems to result from ultraviolet absorption by free p‐BB− ions followed by intermolecular energy transfer to free EuEDTA− ions. The analogous water systems containing o‐BB− or m‐BB− are nonfluorescent, although all three of the solid hydrated salts Eu(o‐BB)3, Eu(m‐BB)3, and Eu(p‐BB)3 fluoresce brightly at room temperature.

Spectroscopic and Laser Properties of Europium α‐Naphthoyltrifluoroacetonate in Solution

Ultraviolet radiation absorbed by the organic ligands surrounding the europium ion in europium α‐naphthoyltrifluoroacetonate Eu(α‐NTF)4− is efficiently converted via intramolecular energy transfer to fluorescence characteristic of Eu3+. The quantum efficiency for this process is shown to be a constant from 2600 to 3900 A in acetonitrile solution. Laser operation has been observed at temperatures up to −10°C. The effect of the relatively high scattering losses on both the threshold and the radiance of the laser are discussed.

The heat stabilities of trivalent metal 8-quinolinol chelates in inert atmospheres

Abstract The thermal stabilities of Al, Ga, In, Cr and Fe oxinates have been studied by thermogravimetry, differential thermal analysis, thermomanometric analysis and by a sealed tube extraction technique. The order of decreasing heat stability for the anhydrous chelates is Al>Cr~Ga>In>Fe. The compounds decompose with the evolution of hydrogen and the formation of large amounts of carbonaceous residue. The Al, Cr, Ga, and In oxinates can be melted without major decomposition when heated rapidly.

Magnetite dissolution and crevice studies with chelant solutions

Work is described in two related areas: (a) fundamental studies of the dissolution behavior of synthetic magnetite in aqueous chelant solutions as functions of solution pH, temperature, heating time, chelant structure, and the presence of additives, and (b) more applied investigations in which information from the basic studies was utilized in choosing solutions and experimental conditions for the removal of magnetite based corrosion products from simulated steam generator tube-tube support plate crevices. The magnetite dissolution work has employed a novel, convenient, and sensitive experimental technique based on the ferromagnetism characteristic of Fe/sub 3/O/sub 4/. Since chemical reaction of magnetite with chelants results in nonmagnetic iron chelates, monitoring the ferromagnetism of a reaction mixture, as a whole, provides an in situ and quantitative measure of unconsumed magnetite.