{
  "abstract": "The lower critical solution temperature (LCST) mechanism of aqueous triethylamine (TEA) solution was investigated by the element-specific observation of molecular interactions using soft X-ray absorption spectroscopy (XAS). The H 2 O‒H 2 O hydrogen bonds were probed by O K-edge XAS, and the hydrophobic interactions of TEA and TEA‒H 2 O hydrogen bonds were probed by C and N K-edge XAS. Molecular interactions in aqueous TEA solutions at temperatures below the LCST were analyzed using radial distribution functions obtained from molecular dynamics (MD) simulations. Temperature-dependent changes in the XAS spectra were evaluated by inner-shell calculations using snapshots from MD simulations. These studies revealed that the LCST mechanism of aqueous TEA solution is governed by the balance of H 2 O‒H 2 O hydrogen bonds, hydrophobic interactions of TEA, and TEA‒H 2 O hydrogen bonds. Aqueous TEA solution is miscible below the LCST, where the H 2 O‒H 2 O hydrogen bonds elongate owing to the TEA‒H 2 O hydrogen bonds and hydrophobic interactions of TEA. The H 2 O‒H 2 O hydrogen bonds near the LCST are closer to those of liquid water owing to the weakening of the TEA‒H 2 O hydrogen bonds. The hydrophobic interactions of TEA are also enhanced owing to the strong H 2 O‒H 2 O hydrogen bonds, resulting in liquid‒liquid phase separation above the LCST. These three factors provide a framework for interpreting the LCST mechanisms of amphiphilic molecules, polymers, and soft matter related to protein folding and DNA packing.",
  "abstract_shown": true,
  "affiliations": [
    "Institute for Molecular Science, Myodaiji, Okazaki, Japan, 444-8585",
    "Graduate Institute for Advanced Studies, SOKENDAI, Myodaiji, Okazaki, Japan, 444-8585",
    "Department of Chemistry",
    "Zhejiang University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Masanari Nagasaka",
      "orcid": "0000-0002-6249-6553"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "Kenji Mochizuki",
      "orcid": "0000-0002-8947-9980"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0c2e62nng6n50.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009325/v1",
  "fulltext_url": null,
  "id": "0c2e62nng6n50",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009325/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3107|Spectroscopy and Quantum Chemical Studies"
    ]
  ],
  "openalex": "W7214077924",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15009325/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-22",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/0c2e62nng6n50.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:21Z",
      "native_id": "10.26434/chemrxiv.15009325",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009325/v1"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3107|Spectroscopy and Quantum Chemical Studies",
      "subfield": "amo"
    }
  ],
  "title": "Water hydrogen bond network elongation below the lower critical solution temperature in aqueous triethylamine solution probed by soft X-ray absorption spectroscopy",
  "title_text": "Water hydrogen bond network elongation below the lower critical solution temperature in aqueous triethylamine solution probed by soft X-ray absorption spectroscopy",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:21Z",
  "url": "https://research.draconitic.com/paper/0c2e62nng6n50",
  "venue": "ChemRxiv",
  "versions": []
}