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Journal Articles

Extended X-ray absorption fine structure spectroscopy measurements and molecular dynamics simulations reveal the hydration structure of the radium(II) ion

Yamaguchi, Akiko; Nagata, Kojiro*; Kobayashi, Keita; Tanaka, Kazuya; Kobayashi, Toru; Tanida, Hajime; Shimojo, Kojiro; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

iScience (Internet), 25(8), p.104763_1 - 104763_12, 2022/08

https://doi.org/10.1016/j.isci.2022.104763

Times Cited Count：9 Percentile：68.46(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Lanthanide extraction using a thiodiglycolamic acid extractant; Effect of S-donor on lanthanide separation

Shimojo, Kojiro; Fujiwara, Iori*; Oshima, Tatsuya*; Yokoyama, Keiichi; Yaita, Tsuyoshi

Analytical Sciences, 38(7), p.1003 - 1006, 2022/07

https://doi.org/10.1007/s44211-022-00123-5

Times Cited Count：0 Percentile：0(Chemistry, Analytical)

Liquid-liquid extraction of lanthanide (Ln) ions was investigated using -dioctylthiodiglycolamic acid (DOTDGAA), which is a sulfur donor ligand with an amide group and a carboxyl group connected by a thioether chain. The extraction performance and selectivity of DOTDGAA for Ln ions were compared with those of -dioctyldiglycolamic acid (DODGAA), which is also an oxygen donor ligand with a similar chemical structure, to assess the effect of the soft/hard donor atom on Ln separation. DOTDGAA quantitatively extracted all Ln ions while being selective toward light and middle Ln ions, in contrast to the selectivity of DODGAA for heavier Ln ions. Slope analysis demonstrated that the Ln $^{3+}$ transfer using DOTDGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, Ln(DOTDGAA) $_{3}$ . The back-extraction of Ln ions from the extracting phase was successfully achieved under acidic conditions.

Journal Articles

Marking actinides for separation; Resonance-enhanced multiphoton charge transfer in actinide complexes

Matsuda, Shohei; Yokoyama, Keiichi; Yaita, Tsuyoshi; Kobayashi, Toru; Kaneta, Yui; Simonnet, M.; Sekiguchi, Tetsuhiro; Honda, Mitsunori; Shimojo, Kojiro; Doi, Reisuke; et al.

Science Advances (Internet), 8(20), p.eabn1991_1 - eabn1991_11, 2022/05

https://doi.org/10.1126/sciadv.abn1991

Times Cited Count：6 Percentile：58.16(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Investigation of hydration and adsorption structures on clay minerals of radium by EXAFS

Yamaguchi, Akiko; Nagata, Kojiro*; Tanaka, Kazuya; Kobayashi, Keita; Kobayashi, Toru; Shimojo, Kojiro; Tanida, Hajime; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

Hosha Kagaku, (45), p.28 - 30, 2022/03

no abstracts in English

Journal Articles

Study on phenanthroline carboxamide for lanthanide separation; Influence of amide substituents

Simonnet, M.; Kobayashi, Toru; Shimojo, Kojiro; Yokoyama, Keiichi; Yaita, Tsuyoshi

Inorganic Chemistry, 60(17), p.13409 - 13418, 2021/09

https://doi.org/10.1021/acs.inorgchem.1c01729

Times Cited Count：15 Percentile：87.32(Chemistry, Inorganic & Nuclear)

Journal Articles

Solvent extraction of technetium(VII) and rhenium(VII) using a hexaoctylnitrilotriacetamide extractant

Shimojo, Kojiro; Suzuki, Hideya; Yokoyama, Keiichi; Yaita, Tsuyoshi; Ikeda, Atsushi

Analytical Sciences, 36(12), p.1435 - 1437, 2020/12

https://doi.org/10.2116/analsci.20C014

Times Cited Count：13 Percentile：64.65(Chemistry, Analytical)

Liquid-liquid extraction for the removal of pertechnetate ( $^{99}$ TcO $_{4}$ $^{-}$ ) and perrhenate (ReO $_{4}$ $^{-}$ ) is reported using tripodal extractant -hexa--octylnitrilotriacetamide (HONTA) composed of three amide groups and a tertiary amine. The extraction behavior was compared with those using alkyldiamideamines (ADAAM(Oct) and ADAAM(EH)), and the commercial amine-type extractant, trioctylamine (TOA). HONTA quantitatively extracted $^{99}$ TcO $_{4}$ $^{-}$ and ReO $_{4}$ $^{-}$ in the pH range from 1.0 to 2.5 by co-extraction of protons. Extraction performance of extractants was improved in the order of HONTA ADAAM(Oct) ADAAM(EH) TOA. $^{99}$ TcO $_{4}$ $^{-}$ and ReO $_{4}$ $^{-}$ in the extracting phase were successfully stripped using neutral aqueous solutions as the receiving phase, and the extraction ability of HONTA was maintained after five repeated uses.

Journal Articles

Synergistic enhancement of the extraction and separation efficiencies of lanthanoid(III) ions by the formation of charged adducts in an ionic liquid

Okamura, Hiroyuki; Mizuno, Masayoshi*; Hirayama, Naoki*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

Industrial & Engineering Chemistry Research, 59(1), p.329 - 340, 2020/01

https://doi.org/10.1021/acs.iecr.9b04998

Times Cited Count：15 Percentile：57.71(Engineering, Chemical)

The synergistic ionic-liquid extraction and extraction equilibrium of lanthanoid(III) (Ln(III)) ions have been investigated using 2-thenoyltrifluoroacetone (Htta) and trioctylphosphine oxide (TOPO) in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C $_{4}$ mim][Tf $_{2}$ N]). The selective synergistic effect for heavier Ln(III) ions was found using a combination of Htta and TOPO in [C $_{4}$ mim][Tf $_{2}$ N], leading to enhanced separability among Ln(III) ions. The extracted Ln(III) species and the extraction constants in the Htta-TOPO system were determined by three-dimensional extraction equilibrium analysis. The selective synergism for heavier Ln(III) ions in the Htta-TOPO system was ascribed to the formation of hydrophobic, charged adducts, such as Ln(tta) $_{2}$ (TOPO) $_{3}$ $^{+}$ and Ln(tta)(TOPO) $_{3}$ $^{2+}$ , in [C $_{4}$ mim][Tf $_{2}$ N].

Journal Articles

Solvent extraction in analytical separation techniques

Shimojo, Kojiro

Analytical Sciences, 34(12), p.1345 - 1346, 2018/12

https://doi.org/10.2116/analsci.highlights1812

Solvent extraction is one of the most effective analytical methods for separation, purification, and removal of target metal ions (e.g. valuable metal ions, toxic metal ions and radioactive fission products) from aqueous solutions containing various metal ions. In this paper, we introduce the papers related to (1) novel extractant, (2) ionic liquids and deep eutectic solvents, (3) new extractors, among papers on solvent extraction published between 2016 and 2018.

Journal Articles

Extraction ability of 4-benzoyl-3-phenyl-5-isoxazolone towards 4f-ions into ionic and molecular media

Atanassova, M.*; Okamura, Hiroyuki; Eguchi, Ayano; Ueda, Yuki; Sugita, Tsuyoshi; Shimojo, Kojiro

Analytical Sciences, 34(8), p.973 - 978, 2018/08

https://doi.org/10.2116/analsci.18P166

Times Cited Count：17 Percentile：59.57(Chemistry, Analytical)

The distribution constants of 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) and deprotonated one (PBI $^{-}$ ) between hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C $_{1}$ C $_{4}$ im][Tf $_{2}$ N]) and aqueous phases were determined, together with the acid-dissociation constant of HPBI. The solvent extraction of three selected lanthanoid ions (La $^{3+}$ , Eu $^{3+}$ , and Lu $^{3+}$ ) with HPBI from aqueous nitrate phase into [C $_{1}$ C $_{4}$ im][Tf $_{2}$ N] has been investigated. Application of the ionic liquid as the extracting phase greatly enhanced the extraction performance of HPBI for lanthanoid ions compared with that in the chloroform system. The composition of the extracted species was established to be anionic tetrakis entities, Ln(PBI) $_{4}$ $^{-}$ , for light, middle, and heavy lanthanoid ions in an ionic environment.

Journal Articles

A Comprehensive extraction study using a mono-alkylated diglycolamic acid extractant; Comparison between a secondary amide group and a tertiary amide group

Sugita, Tsuyoshi; Fujiwara, Iori*; Okamura, Hiroyuki; Oshima, Tatsuya*; Baba, Yoshinari*; Naganawa, Hirochika; Shimojo, Kojiro

Solvent Extraction Research and Development, Japan, 24(2), p.61 - 69, 2017/05

http://www.solventextraction.gr.jp/serdj/jurnalpdf/vol24(2)/24_61.pdf

We investigated an influence of amide group in diglycolamic acid-type extractants on extraction property of metal ions. The extraction characteristics of -dodecyldiglycolamic acid (C $_{12}$ DGAA), with a secondary amide group, for 56 metal ions have been investigated, and compared with those of -dioctyldiglycolamic acid (DODGAA) with a tertiary amide group. Compared with DODGAA, C $_{12}$ DGAA has a poor extraction performance and separation ability for rare-earth metal ions, except for Sc(III). However, C $_{12}$ DGAA tended to provide better extraction for relatively small-sized metal ions than DODGAA. In addition, it was found that C $_{12}$ DGAA enables the selective removal of Hg(II) from aqueous solutions containing various divalent metal ions.

Journal Articles

Development of ion exchange ligands with high separation performance and colorimetric analysis using gold nanoparticles decorated with the functional ligands

Shimojo, Kojiro

Nihon Ion Kokan Gakkai-Shi, 28(1), p.1 - 10, 2017/01

https://doi.org/10.5182/jaie.28.1

Development of metal separating reagents with high selectivity is necessary for efficient separation and recovery of valuable metals contained in industrial wastes, and removal and detection of toxic metals. We have developed novel metal separating ligands with a diglycolamic acid (DGAA) framework. The ligands have a tridentate coordination structure consisting of an amide group and a carboxy group connected by an ether chain and provide a metal separation ability superior to that of commercial ligands. Since the ligands can be synthesized simply in one step, this helps to reduce the production costs of the ligands. In the present review article, we report the extraction characteristics of DGAA-type ligand for 56 kinds of metal ions, extraction separation of rare-earth metal ions, and removal of toxic metal ions. Furthermore, a one-pot biological approach to fabricate DGAA-decorated gold nanoparticles has been developed using the DGAA-type ligand fused to the N-terminus of a gold-binding peptide. It was found that the DGAA-decorated gold nanoparticles can act as a high-sensitive colorimetric sensor for detecting toxic metal ions with color change.

Journal Articles

Role of Tf $_{2}$ N $^{-}$ anions in the ionic liquid-water distribution of europium(III) chelates

Okamura, Hiroyuki; Aoyagi, Noboru; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

RSC Advances (Internet), 7(13), p.7610 - 7618, 2017/01

https://doi.org/10.1039/C6RA27208H

Times Cited Count：20 Percentile：56.92(Chemistry, Multidisciplinary)

The role of bis(trifluoromethanesulfonyl)imide (Tf $_{2}$ N $^{-}$ ) anions in the ionic liquid-water distribution systems of the Eu(III) chelates with 2-thenoyltrifluoroacetone (Htta) was investigated by the liquid-liquid distribution and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The effect of the ionic liquids on the distribution constant of Eu(tta) $_{3}$ was evaluated by the regular solution theory. The distribution constant of Eu(tta) $_{3}$ in 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C $_{n}$ mim][Tf $_{2}$ N]) was increased dramatically by the solvation effects of Eu(tta) $_{3}$ in [C $_{n}$ mim][Tf $_{2}$ N]. TRLFS for [Eu(tta) $_{3}$ (H $_{2}$ O) $_{3}$ ] synthesized revealed that the Eu(tta) $_{3}$ chelate was almost completely dehydrated in a series of [C $_{n}$ mim][Tf $_{2}$ N]. The Eu(tta) $_{3}$ chelate exists as di- or tri-hydrates in 1-ethyl-3-methylimidazolium perchlorate ([C $_{2}$ mim][ClO $_{4}$ ]) containing 20 M water, whereas mono-hydrated chelate was formed in [C $_{2}$ mim][Tf $_{2}$ N, ClO $_{4}$ ] in the presence of 0.50 M Tf $_{2}$ N $^{-}$ and 20 M water. These results show that the coordinated water molecules of [Eu(tta) $_{3}$ (H $_{2}$ O) $_{3}$ ] were replaced by the Tf $_{2}$ N $^{-}$ anions. In fact, an anionic adduct, [Eu(tta) $_{3}$ (Tf $_{2}$ N)] $^{-}$ , was observed by electrospray ionization mass spectrometry in the presence of [C $_{4}$ mim][Tf $_{2}$ N].

Journal Articles

Solvent extraction and synergistic effect using an ionic liquid

Okamura, Hiroyuki; Shimojo, Kojiro

Ion Ekitai Kenkyu Saizensen To Shakai Jisso, p.220 - 227, 2016/12

Solvent extraction is a separation method based on the difference in the distribution of solutes between two immiscible liquid phases. Recently, ionic liquids have been widely investigated as novel extraction media. Solvent properties of an ionic liquid can be adjusted by combination of a cationic and an anionic component. It is, therefore, possible to provide an attractive reaction field as an extraction medium. In this article, specific extraction phenomena observed in the ionic liquid extraction system for metal ions were introduced.

Journal Articles

Extraction behavior of rare-earth elements using a mono-alkylated diglycolamic acid extractant

Shimojo, Kojiro; Fujiwara, Iori*; Fujisawa, Kiyoshi*; Okamura, Hiroyuki; Sugita, Tsuyoshi; Oshima, Tatsuya*; Baba, Yoshinari*; Naganawa, Hirochika

Solvent Extraction Research and Development, Japan, 23(2), p.151 - 159, 2016/05

http://doi.org/10.15261/serdj.23.151

Liquid-liquid extraction of rare-earth (RE) cations has been investigated using -dodecyldiglycolamic acid (C $_{12}$ DGAA) with a secondary amide group, and compared with that using -dioctyldiglycolamic acid (DODGAA) with a tertiary amide group. C $_{12}$ DGAA enables quantitative transfer of all RE cations from moderately acidic solution, while being selective toward the heavier RE cations, and performs better than typical carboxylic-acid-type extractants. However, C $_{12}$ DGAA provides low extraction performance and separation ability for RE cations compared with DODGAA because of the weaker basicity of the amide oxygen. Slope analysis demonstrated that RE $^{3+}$ transfer with C $_{12}$ DGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, RE(C $_{12}$ DGAA) $_{3}$ . Structural characterization by X-ray diffraction revealed that three -butyldiglycolamic acid (C $_{4}$ DGAA) molecules coordinated to the La $^{3+}$ central ion in a tridentate fashion and the La $^{3+}$ primary coordination sphere consisted of three oxygen atoms from the amide group, three oxygen atoms from the ether group, and three oxygen atoms from the carboxy group.

Journal Articles

Photophysical property of -bis(thiocyanato)aurate(I) complexes in ionic liquids

Aoyagi, Noboru; Shinha, Yusuke*; Ikeda, Atsushi*; Haga, Yoshinori; Shimojo, Kojiro; Brooks, N. R.*; Izuoka, Akira*; Naganawa, Hirochika; Kimura, Takaumi; Binnemans, K.*

Crystal Growth & Design, 15(3), p.1422 - 1429, 2015/03

https://doi.org/10.1021/cg501792m

Times Cited Count：11 Percentile：64.34(Chemistry, Multidisciplinary)

The photochemistry of a gold(I) thiocyanate complex has been investigated to determine the coordination structure in both the solid and liquid states. The coordination geometries of the supramolecular complex and the concomitant exciplex have mainly been analyzed by crystallographic analysis and X-ray absorption spectroscopy. The Au-S bond distance and Au-Au separation of the compound in the ground state and in the phosphorescent excited state were compared. Upon irradiation with UV light, the excimeric interactions were enhanced, resulting in a contraction of the Au-Au aurophilic distance. A broad luminescence spectrum was observed for the one-dimensional chain suprastructure. The time-resolved luminescence spectra indicated the entity of several oligomeric species in the crude liquid without neutral solvent molecules. In addition, EXAFS spectroscopy exhibited a slight change in the nearest Au-S distance due to the photo-switched transformation. The deformation of the (Au-Au)* exciplexes was not apparently promoted in the liquid state with the asymmetrical imidazoium cations having a non-local charge distribution in the present observation. This is plausibly due to a flexible molecular structure and a property in the liquid state. In conclusion, the photo-excited nature of the pseudo-one dimensional complexes is emerged in controlling bond distances among the supramolecular networks.

Journal Articles