This entry presents Theophylline (C7H8N4O2; CAS 58-55-9; PubChem CID 2153) as a 3D-printable ball-and-stick model in which every atom carries its engraved element symbol (C, H, N, O), so the model can be read without a colour key. Atomic coordinates come from the PubChem-computed 3D conformer (not an experimental crystal structure); coordinates and connectivity are unchanged.

Structure at a glance

• 21 atoms: 7 C, 8 H, 4 N, 2 O

• 22 bonds: 15 single, 3 double, 4 aromatic

• Two rings (one 5-membered and one 6-membered), fused along a shared edge, one of them aromatic

• Functional group: one pyridine-type ring nitrogen

• One hydrogen-bond donor and three acceptors (computed)

• Fraction of sp3-hybridised (tetrahedral) carbon atoms: 0.29 (computed)

Use in teaching

• Counting task: students tally the engraved symbols (7 C, 8 H, 4 N, 2 O; 21 atoms) and rebuild the formula C7H8N4O2 from the model alone.

• Aromaticity: identify the aromatic ring among the two rings and the 4 bonds recorded as aromatic.

• Functional groups: find the pyridine-type ring nitrogen on the model and name it.

File and printing

STL mesh of 281,566 triangles, a closed (watertight) single solid. Coordinates are in ångström and STL stores no unit, so scale the model deliberately in your slicer. Measured bounding box: 6.742 × 6.025 × 6.281 Å; at scale factor 10 (1 Å to 10 mm, file read in millimetres) the print measures about 67.4 × 60.2 × 62.8 mm. SHA-256: 80f9f9f9e6f4af388d023646b7bb7b82e92905784772559a12ba0106037c6878.

Validation

• InChIKey identical to the PubChem record (PubChem FTP SDF, file dated 2026-10-08): ZFXYFBGIUFBOJW-UHFFFAOYSA-N

• Molecular formula and hydrogen-bond donor/acceptor counts identical to PubChem

• Mesh: triangle count in the header equals the actual count; 0 edges not shared by exactly two triangles; 1 connected solid; SHA-256 equal to the published file

Source, licence and identifiers

Full record: molgod.org/molecule/58-55-9 · Licence and provenance record: molgod.org/licenses/stl/58-55-9 · Same file on Wikimedia Commons: File:Theophylline-3D-molecular-model-engraved-CAS-58-55-9.stl

• MolGod ID: MG_539-553-941-70

• Wikidata: Q407308

• EC number: 200-385-7

• ChemSpider ID: 2068

• IUPAC name: 1,3-dimethyl-7H-purine-2,6-dione

• InChIKey: ZFXYFBGIUFBOJW-UHFFFAOYSA-N

• SMILES: CN1C2=C(C(=O)N(C1=O)C)NC=N2

• Molar mass 180.16 g/mol (exact mass 180.06472551)

Licence: CC BY-SA 4.0 (licence text). Required attribution: "Theophylline 3D model by MolGod.org — https://molgod.org/molecule/58-55-9/ — CC BY-SA 4.0".