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Journal Articles

Unusually kinetically inert monocationic neptunyl complex with a fluorescein-modified 1,10-phenanthroline-2,9-dicarboxylate ligand; Specific separation and detection in gel electrophoresis

Yamagata, Kazuhito*; Ouchi, Kazuki; Marumo, Kazuki*; Tasaki-Handa, Yuiko*; Haraga, Tomoko; Saito, Shingo*

Inorganic Chemistry, 62(2), p.730 - 738, 2023/01

https://doi.org/10.1021/acs.inorgchem.2c02908

Times Cited Count：3 Percentile：74.01(Chemistry, Inorganic & Nuclear)

The inert NpO $_{2}$ $^{+}$ complex with a fluorescein-modified phenanthroline-2,9-dicarboxylic acid was found by kinetic selection using polyacrylamide gel electrophoresis (PAGE) from a small chemical library. The small spontaneous dissociation rate constant of 810 $^{-6}$ s $^{-1}$ (the half-life of 23 hours) was determined. This is the singly-charged NpO $_{2}$ $^{+}$ complex exhibiting unusual kinetic inertness in aqueous solution, one million times slower than widely accepted fast kinetics of neptunyl complexes. Selective fluorescence detection of NpO $_{2}$ $^{+}$ was achieved in PAGE with a detection limit of 68 pmol dm $^{-3}$ (17 fg). This system was successfully applied to simulated spent nuclear fuel and high-level radioactive waste samples.

Journal Articles

Rotation of complex ions with ninefold hydrogen coordination studied by quasielastic neutron scattering and first-principles molecular dynamics calculations

Omasa, Yoshinori*; Takagi, Shigeyuki*; Toshima, Kento*; Yokoyama, Kaito*; Endo, Wataru*; Orimo, Shinichi*; Saito, Hiroyuki*; Yamada, Takeshi*; Kawakita, Yukinobu; Ikeda, Kazutaka*; et al.

Physical Review Research (Internet), 4(3), p.033215_1 - 033215_9, 2022/09

https://doi.org/10.1103/PhysRevResearch.4.033215

Journal Articles

Characterization of adsorbed alkali metal ions in 2:1 type clay minerals from first-principles metadynamics

Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi

Journal of Physical Chemistry A, 119(30), p.8369 - 8375, 2015/07

https://doi.org/10.1021/acs.jpca.5b05934

Times Cited Count：21 Percentile：65.95(Chemistry, Physical)

Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs $^{+}$ in the 2:1 type trioctahedral clay minerals with saponitelike compositions, where lighter alkali ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs $^{+}$ is found to result partially from the capability of recognizing selectively Cs $^{+}$ ions at basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.

Journal Articles

Electrochemical properties of uranium(VI) complexes with multidentate ligands in -dimethylformamide

Kim, S.-Y.; Asakura, Toshihide; Morita, Yasuji; Ikeda, Yasuhisa*

Journal of Alloys and Compounds, 408-412, p.1291 - 1295, 2006/02

https://doi.org/10.1016/j.jallcom.2005.04.123

Times Cited Count：10 Percentile：54.57(Chemistry, Physical)

The electrochemical reactions of UO $_{2}$ (-diketonato) $_{2}$ DMF, UO $_{2}$ (trop) $_{2}$ DMF and UO $_{2}$ (sap)(DMF) $_{2}$ , (DMF = N,N-dimethylformamide, -diketonate = thenoyltrifluoroacetonate (ttfa), benzoyltrifluoroacetonate (btfa), and dibenzoylmethanate(dbm), trop = tropolonate, and sap = 2-salicylidenaminophenolate) complexes in DMF solution containing tetrabutyl ammonium perchlorate as a supporting electrolyte have been studied with cyclic voltammetry. These uranyl(VI) complexes were found to be quasi-reversibly reduced to U(V) species. The formal redox potentials (E $^{o}$ , . ferrocene/ferrocenium) for U(VI)/U(V) couples were determined to be -1.18 V for UO $_{2}$ (ttfa) $_{2}$ DMF, -1.18 V for UO $_{2}$ (btfa) $_{2}$ DMF, -1.46 V for UO $_{2}$ (dbm) $_{2}$ DMF, -1.46 V for UO $_{2}$ (trop) $_{2}$ DMF, and -1.59 V for UO $_{2}$ (sap)(DMF) $_{2}$ .