Role of Alkyl Chain Branching in the Self-Assembly of Nitrilotriacetamide-Based Lanthanide Extractants

Ueda, Yuki; Kobayashi, Toru; Nakamura, Satoshi; Ban, Yasutoshi; Kaneta, Yui; Nabatame, Nozomi; Micheau, C.; Tokunaga, Kohei; Nakabe, Rintaro; Kaneko, Masashi*; et al.

Langmuir, 42(1), p.1613 - 1626, 2026/01

https://doi.org/10.1021/acs.langmuir.5c05651

Understanding the structural factors governing the metal ions selectivity of solvent extraction systems is crucial for developing advanced processes for partitioning and transmutation of high-level radioactive waste. Here, we systematically investigated the effect of alkyl side-chain branching in nitrilotriacetamide (NTAamide) extractants on the extraction of lanthanum (La) and neodymium (Nd), chosen as representative lanthanides. Four extractants having each eight carbon atoms as one of the amide chains with identical molecular weights but different degrees of alkyl branching were examined. Distribution ratios were measured as a function of HNO concentration, and the local coordination structures of La and Nd were analyzed by extended X-ray absorption fine structure (EXAFS), while supramolecular aggregation in the organic phase was characterized by small-angle neutron scattering (SANS). EXAFS analysis revealed that the inner-sphere coordination environment of La and Nd was essentially unaffected by the degree of alkyl branching. In contrast, SANS results showed that extractants with fewer branched alkyl groups formed larger aggregates at low HNO concentrations, particularly in the case of Nd, where aggregation was found to facilitate extraction and prevent precipitation of poorly soluble complexes. These findings demonstrate that alkyl branching strongly influences supramolecular aggregation, which in turn governs extraction behavior. This work highlights the potential of nanoscale structural control as a new design concept for improving selectivity in lanthanide and actinide solvent extraction systems.

Formation of rod-like particles with periodic interior by hydroxypropylmethyl cellulose samples with narrow molar mass distributions in aqueous solutions

Yoshida, Misato*; Arai, Kengo*; Nakagawa, Daiki*; Horikawa, Yoshiki*; Iwase, Hiroki*; Kumada, Takayuki; Motokawa, Ryuhei; Shikata, Toshiyuki*

Biomacromolecules, 26(11), p.8332 - 8342, 2025/11

https://doi.org/10.1021/acs.biomac.5c01969

Effects of the size of fillers on viscoelasticity in the glassy state of poly(styrene--butadiene) reinforced by carbon black

Watanabe, Yuki*; Kumagawa, Daiki*; Karitani, Shu*; Inoue, Tadashi*; Iwabuki, Hitoshi*; Nakanishi, Yohei*; Shibata, Motoki*; Motokawa, Ryuhei; Sugita, Tsuyoshi; Ueda, Yuki; et al.

Macromolecules, 58(16), p.8641 - 8648, 2025/08

https://doi.org/10.1021/acs.macromol.5c01357

Fluorous and organic extraction systems; A Comparison from the perspectives of coordination structures, interfaces, and bulk extraction phases

Ueda, Yuki; Micheau, C.; Akutsu, Kazuhiro*; Tokunaga, Kohei; Yamada, Masako*; Yamada, Norifumi*; Bourgeois, D.*; Motokawa, Ryuhei

Langmuir, 40(46), p.24257 - 24271, 2024/11

https://doi.org/10.1021/acs.langmuir.4c02268

Microscopic structures in liquid-liquid extraction, such as structuration between extractants or extracted complexes in bulk organic phases and at interfaces, can influence macroscopic phenomena, such as the distribution behavior of solutes, including extraction efficiency, selectivity, and phase separation of the organic phase. In this study, we correlated the macroscopic behavior of the extraction of Zr(IV) ions from nitric acid solutions with microscopic structural information in order to understand at the molecular level the key factors contributing to the higher metal ion extraction performance in the fluorous extraction system comprising fluorous phosphate (TFP) in perfluorohexane as compared to the analogous organic extraction system comprising organic phosphate (THP) in n-hexane. Extended X-ray absorption fine structure, neutron reflectometry, and small-angle neutron scattering revealed the local coordination structure around the Zr(IV) ion, the accumulation of extractant molecules at the interface, and the structuration of extractant molecules in the bulk extraction phase, respectively. In the fluorous extraction system, extractant aggregates with were formed after contact with nitric acid. In contrast, in the organic extraction system, only extractant dimers were formed. We speculate that differences in the local coordination structure around the Zr(IV) ion and the structuration of the extractant molecules in the bulk extraction phase contribute to the high Zr(IV) extraction performance in the fluorous extraction system. In particular, the size of the aggregates hardly changed with increasing Zr(IV) concentration in the fluorous phase, which may be closely related to the absence of phase splitting in the fluorous extraction system.

A Focusing supermirror for time-of-flight grazing-incidence small-angle neutron scattering measurement

Yamazaki, Dai; Maruyama, Ryuji; Aoki, Hiroyuki; Hanashima, Takayasu*; Akutsu-Suyama, Kazuhiro*; Miyata, Noboru*; Soyama, Kazuhiko

Quantum Beam Science (Internet), 9(2), p.20_1 - 20_12, 2024/06

https://doi.org/10.3390/qubs9020020

Star-polymer-DNA gels showing highly predictable and tunable mechanical responses

Ohira, Masashi*; Katashima, Takuya*; Naito, Mitsuru*; Aoki, Daisuke*; Yoshikawa, Yusuke*; Iwase, Hiroki*; Takata, Shinichi; Miyata, Kanjiro*; Chung, U.-I.*; Sakai, Takamasa*; et al.

Advanced Materials, 34(13), p.2108818_1 - 2108818_9, 2022/01

https://doi.org/10.1002/adma.202108818

Distinguishing adsorbed and deposited ionomers in the catalyst layer of polymer electrolyte fuel cells using contrast-variation small-angle neutron scattering

Harada, Masashi*; Takata, Shinichi; Iwase, Hiroki*; Kajiya, Shuji*; Kadoura, Hiroaki*; Kanaya, Toshiji*

ACS Omega (Internet), 6(23), p.15257 - 15263, 2021/06

https://doi.org/10.1021/acsomega.1c01535

NACore amyloid formation in the presence of phospholipids

Pallbo, J.*; Imai, Masayuki*; Gentile, L.*; Takata, Shinichi; Olsson, U.*; Sparr, E.*

Frontiers in Physiology (Internet), 11, p.592117_1 - 592117_13, 2020/12

https://doi.org/10.3389/fphys.2020.592117

Preparation, characterization, and dilute solution properties of four-branched cage-shaped poly(ethylene oxide)

Noda, Takashi*; Doi, Yuya*; Ota, Yutaka*; Takata, Shinichi; Takano, Atsushi*; Matsushita, Yushu*

Journal of Polymer Science, 58(15), p.2098 - 2107, 2020/08

https://doi.org/10.1002/pol.20200286

The Effect of alkyl ammonium ionic liquids on thermal denaturation aggregation of -lactoglobulin

Yoshida, Koji*; Zenin, Tomohiro*; Fujiyoshi, Ayako*; Sanada, Yusuke*; Yamaguchi, Toshio*; Murata, Kunihiko*; Takata, Shinichi; Hiroi, Kosuke; Takahiro, Takekiyo*; Yoshimura, Yukihiro*

Journal of Molecular Liquids, 293, p.111477_1 - 111477_9, 2019/11

https://doi.org/10.1016/j.molliq.2019.111477