{
  "abstract": "Internal functionalization can reorganize intermolecular interactions across a self-assembled monolayer (SAM), yet its depth-dependent consequences remain poorly understood. Here, molecular dynamics simulations and vibrational sum-frequency generation (VSFG) spectroscopy reveal a dual structural response in N-(2-mercaptoethyl)heptanamide SAMs on Au(111). A persistent intermolecular hydrogen-bond network suppresses conformational fluctuations between the Au-S interface and the amide plane. Above this plane, however, the larger volume of the amide increases alkyl-chain separation and weakens van der Waals coupling and enhances conformational flexibility with temperature. Thus, a hydrogen-bond-stabilized, solid-like lower region coexists with a weakly coupled, liquid-like upper region. Simulated VSFG spectra reproduce the observed terminal CH3 stretching-mode intensities, including the enhanced asymmetric response. This response occurs without a correspondingly large average methyl tilt angle because inequivalent molecular environments produce broad, heterogeneous orientation distributions. Consequently, the conventional assignment of a single methyl tilt angle from VSFG intensity ratio breaks down for internally functionalized SAMs.",
  "abstract_shown": true,
  "affiliations": [
    "Institute for Basic Science (IBS",
    "Department of Chemistry",
    "Korea University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Saima Sadiq"
    },
    {
      "affs": [
        0
      ],
      "name": "Hojeong Yoon"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Junhyeok Park"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Kyungwon Kwak",
      "orcid": "0000-0003-1680-0996"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Minhaeng Cho"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/aa137reeb770x.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009617/v1",
  "fulltext_url": null,
  "id": "aa137reeb770x",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009617/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",
      "2208|Molecular Junctions and Nanostructures"
    ]
  ],
  "openalex": "W7214806729",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15009617/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/aa137reeb770x.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:21Z",
      "native_id": "10.26434/chemrxiv.15009617",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009617/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "source:chemrxiv",
      "subfield": "general"
    }
  ],
  "title": "Hydrogen-Bond-Induced Dual Structural Response in Amide-Functionalized Self-Assembled Monolayers",
  "title_text": "Hydrogen-Bond-Induced Dual Structural Response in Amide-Functionalized Self-Assembled Monolayers",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:21Z",
  "url": "https://research.draconitic.com/paper/aa137reeb770x",
  "venue": "ChemRxiv",
  "versions": []
}