{
  "abstract": "Biogenic guanine crystals can incorporate substantial hypoxanthine (Hpx) while retaining the βguanine lattice, but whether the lattice discriminates both dopant identity and local neighborhood remains unresolved. Here, periodic DFT, site-anchored cluster cross-checks, symmetry-complete pair enumeration, and GIPAW 13C calculations connect these two levels of incorporation to experimentally testable observables. In a dry 6.25% fixed-cell model, N7H-Hpx is 21.78 kcal mol ¹ lower in electronic energy than N9H-Hpx; three cluster treatments preserve a 17.40–18.25 ⁻¹ lower in electronic energy than N9H-Hpx; three cluster treatments preserve a 17.40–18.25 kcal mol ¹ preference. A pure-crystal calibration excluding the embedded-Hpx resonance ⁻¹ lower in electronic energy than N9H-Hpx; three cluster treatments preserve a 17.40–18.25 predicts C5 shifts of 115.98 ppm for N7H and 127.94 ppm for N9H, placing N7H-Hpx in the experimentally reported 115–116 ppm region. At 12.5% substitution, 120 site pairs reduce to 13 symmetry-distinct orbits. Fifteen representatives were relaxed, and the corrected orbit means span 2.407 kcal mol ¹, with an adjacent in-plane orbit lowest; independent starts for four low- ⁻¹ lower in electronic energy than N9H-Hpx; three cluster treatments preserve a 17.40–18.25 energy motifs preserve this minimum. Fixed-geometry 700 eV reevaluation in a 4 × 2 × 1 association cycle gives adjacent- and far-pair association energies of −1.2219 and +0.0189 kcal mol ¹. Across four GIPAW pair models, C5 remains comparatively stable, whereas C6/C8 report ⁻¹ lower in electronic energy than N9H-Hpx; three cluster treatments preserve a 17.40–18.25 local arrangement: adjacent and separated motifs yield C8 splittings of 2.854 and 0.037 ppm. Together, the calculations show that the tested β-guanine lattice models discriminate both metabolite identity and relative placement. The resulting ¹³C signatures provide experimentally testable markers of how biologically supplied purine mixtures may become locally organized during biomineralization.",
  "abstract_shown": true,
  "affiliations": [
    "School of Renewable Energy",
    "Inner Mongolia University of Technology",
    "Independent researcher"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "He Hu"
    },
    {
      "affs": [
        2
      ],
      "name": "Li Yi",
      "orcid": "0009-0004-4152-8044"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/74yn4k3eb79xf.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008518/v1",
  "fulltext_url": null,
  "id": "74yn4k3eb79xf",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008518/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",
      "1606|Crystallography and molecular interactions"
    ]
  ],
  "openalex": "W7211974886",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008518/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/74yn4k3eb79xf.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15008518",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008518/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1606|Crystallography and molecular interactions",
      "subfield": "physical"
    }
  ],
  "title": "Hidden Hypoxanthine Neighborhoods in β-Guanine",
  "title_text": "Hidden Hypoxanthine Neighborhoods in β-Guanine",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/74yn4k3eb79xf",
  "venue": "ChemRxiv",
  "versions": []
}