{
  "abstract": "Can single-water microsolvation promote proton sharing in a neutral acid-base complex? We address this question for formic acid-ammonia by isolating its monohydrated complex with broadband rotational spectroscopy and interpreting the resolved 14N hyperfine structure with calibrated high-level quantum chemistry. The observed complex is a single dominant HCOOH-NH3-H2O isomer with effective Cs symmetry, in which NH3 remains the primary proton acceptor, while water closes a cooperative hydrogen-bond cycle by accepting from NH3 and donating to the carbonyl oxygen. Rather than simply stabilizing the binary acid-base contact, this water molecule measurably increases its proton-sharing character. A resolved A/E tunneling pattern from NH3 internal rotation supplies the missing orientation needed to rotate the experimental 14N quadrupole tensor into the local ammonia frame, yielding an experimental χzz component and a quadrupole-derived Townes-Dailey ionicity of approximately 26%. High-level structures show the same directional response: O-H elongation, H···N contraction, and O···N contraction relative to HCOOH-NH3. Together, these results show that one water molecule can promote proton sharing in a neutral formic acid-ammonia complex without producing a separated ion pair.",
  "abstract_shown": true,
  "affiliations": [
    "Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui230026, China.",
    "Deutsches Elektronen-Synchrotron DESY , Notkestr. 85, 22607Hamburg, Germany.",
    "Scuola Superiore Meridionale , Largo San Marcellino 10, Napoli80138, Italy.",
    "INSTM , via G. Giusti 9, Firenze50121, Italy.",
    "Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118Kiel, Germany."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Fan Xie",
      "orcid": "0000-0002-0353-2059"
    },
    {
      "affs": [
        2
      ],
      "name": "Luigi Crisci",
      "orcid": "0000-0002-8140-5397"
    },
    {
      "affs": [
        1
      ],
      "name": "Wenhao Sun",
      "orcid": "0000-0002-2221-0362"
    },
    {
      "affs": [
        2
      ],
      "name": "Federico Lazzari",
      "orcid": "0000-0003-4506-3200"
    },
    {
      "affs": [
        3
      ],
      "name": "Vincenzo Barone",
      "orcid": "0000-0001-6420-4107"
    },
    {
      "affs": [
        1,
        4
      ],
      "name": "Melanie Schnell",
      "orcid": "0000-0001-7801-7134"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/581cza6n63myv.bib",
  "cited_by": 0,
  "doi": "10.1021/jacs.6c13418",
  "fulltext_url": "https://europepmc.org/articles/PMC13693395",
  "id": "581cza6n63myv",
  "issns": [
    "0002-7863",
    "1520-5126"
  ],
  "landing_url": "https://europepmc.org/article/MED/42912363",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1607|Molecular Spectroscopy and Structure"
    ]
  ],
  "openalex": "W7221519263",
  "pdf_url": "https://europepmc.org/articles/PMC13693395?pdf=render",
  "pmcid": "PMC13693395",
  "pmid": "42912363",
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/581cza6n63myv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:14Z",
      "native_id": "MED:42912363",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42912363"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1607|Molecular Spectroscopy and Structure",
      "subfield": "physical"
    }
  ],
  "title": "Single-Water Microsolvation Promotes Proton Sharing in a Neutral Formic Acid-Ammonia Complex.",
  "title_text": "Single-Water Microsolvation Promotes Proton Sharing in a Neutral Formic Acid-Ammonia Complex.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:14Z",
  "url": "https://research.draconitic.com/paper/581cza6n63myv",
  "venue": "Journal of the American Chemical Society",
  "versions": []
}