{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T12:53:03Z","timestamp":1792068783479,"version":"4.4.0"},"reference-count":44,"publisher":"American Chemical Society (ACS)","issue":"41","license":[{"start":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T00:00:00Z","timestamp":1791158400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000165","name":"Division of Chemistry","doi-asserted-by":"publisher","award":["NSF\/CHE-2335833"],"award-info":[{"award-number":["NSF\/CHE-2335833"]}],"id":[{"id":"10.13039\/100000165","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000015","name":"U.S. Department of Energy","doi-asserted-by":"publisher","award":["AC0500OR22725"],"award-info":[{"award-number":["AC0500OR22725"]}],"id":[{"id":"10.13039\/100000015","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,15]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The separation of lanthanide elements by solvent extraction is traditionally governed by differences in the thermodynamic stability of extracted complexes; however, ion-specific interfacial complexation can play an important role in determining selectivity in kinetic separations. Nevertheless, the structural and chemical origins of such interfacial selectivity remain poorly understood. In this work, we combine sum frequency generation (SFG) vibrational spectroscopy with X-ray scattering to resolve interfacial structures of extractant\u2013ion complexes at liquid surfaces. Measurements across pH and lanthanide concentration regimes reveal how changes in aqueous conditions alter the molecular organization of interfacial bis(2-ethylhexyl) phosphoric acid (HDEHP)\u2013lanthanide ion complexes. Across the lanthanide series, light lanthanide ions, e.g., those from La to Dy, tend to form relatively ordered monolayers with HDEHP as characterized by strong CH and weak OH vibrational signals with corresponding electron density profiles and surface ion concentrations. In contrast, heavy lanthanide ions, e.g., those from Er to Lu, tend to produce more disordered interfacial assemblies as reflected by weaker CH stretches, stronger OH signals that are accompanied by surprisingly low lanthanide ion surface densities. These systematic, structural, and chemical differences suggest that HDEHP\u2013heavy lanthanide complexes are more readily organized into increasingly centrosymmetric structures that are poised for transport, explaining their apparent absence at liquid\u2013liquid interfaces at equilibrium. These results establish interfacial organization as a key factor governing lanthanide extraction chemistry and point to kinetic handles to impart unconventional selectivity.<\/jats:p>","DOI":"10.1021\/acs.jpcb.6c03936","type":"journal-article","created":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T16:02:40Z","timestamp":1791216160000},"page":"11002-11010","source":"Crossref","is-referenced-by-count":0,"title":["Lanthanide-Dependent\nSelf-Assembly of Ion-Extractant\nComplexes at Liquid Interfaces: Inversion or Exclusion?"],"prefix":"10.1021","volume":"130","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6128-8656","authenticated-orcid":true,"given":"Pan","family":"Sun","sequence":"first","affiliation":[{"name":"Oak Ridge National Laboratory , , , ,","place":["Oak Ridge, Tennessee, United States, 37831"]},{"name":"Iowa State University , , , ,","place":["Ames, Iowa, United States, 50011"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0289-2965","authenticated-orcid":true,"given":"Uvinduni I.","family":"Premadasa","sequence":"additional","affiliation":[{"name":"Oak Ridge National Laboratory , , , ,","place":["Oak Ridge, Tennessee, United States, 37831"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"suffix":"Jr","given":"David","family":"Walwark","sequence":"additional","affiliation":[{"name":"University of Chicago , , , ,","place":["Chicago, Illinois, United States, 60637"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9996-3733","authenticated-orcid":true,"given":"Wei","family":"Bu","sequence":"additional","affiliation":[{"name":"University of Chicago , , , ,","place":["Chicago, Illinois, United States, 60637"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6429-9329","authenticated-orcid":true,"given":"Benjamin","family":"Doughty","sequence":"additional","affiliation":[{"name":"Oak Ridge National Laboratory , , , ,","place":["Oak Ridge, Tennessee, United States, 37831"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,10,5]]},"reference":[{"key":"2026101508060908200_cit1","doi-asserted-by":"publisher","first-page":"1345","DOI":"10.1039\/C6GC03388A","article-title":"Selective recovery of rare earth elements from ion-adsorption rare\nearth element ores by stepwise extraction with HEH(EHP) and HDEHP","volume":"19","author":"Huang","year":"2017","journal-title":"Green Chem."},{"key":"2026101508060908200_cit2","doi-asserted-by":"publisher","first-page":"10","DOI":"10.1016\/j.mineng.2013.10.021","article-title":"A critical review on\nsolvent extraction of rare earths from aqueous solutions","volume":"56","author":"Xie","year":"2014","journal-title":"Miner. 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