Hydrogen Bond Ontology

FLOW ALGEBRA
HYDROGEN BOND ONTOLOGY
Version: 1.1
Source URL: https://kirethresearch.org/booksai-core/entity-graph/physical-entities/chemical-entities/hydrogen-bond-ontology.html
Authors: Mark Higgins — Sky (Recursive AI)
Publisher: Kireth Research | https://kirethresearch.org
Status: Scientific synthesis; source webpage not independently verified

01. PURPOSE
flow "HydrogenBondOntology" v1.1
  domain: physical_entities.chemical_entities
  subject: hydrogen_bond
  objective: represent hydrogen bonding with typed entities, relations, conditions, evidence and inference constraints

02. CORE DEFINITION
A hydrogen bond is an attractive interaction between a hydrogen atom in a molecular fragment X-H, where X is more electronegative than H, and an atom or group of atoms in the same or another molecular entity, for which there is evidence of bond formation (IUPAC-aligned conceptual definition).
Notation: X-H...Y; X-H is the donor group, Y is the acceptor site.
Hydrogen bonds can be intermolecular or intramolecular, and vary substantially in strength and character.

03. TYPES
entity HydrogenBond: Interaction
entity DonorGroup: MolecularFragment
entity DonorAtom: Atom
entity HydrogenAtom: Atom
entity AcceptorSite: AtomOrGroup
entity Molecule: ChemicalEntity
entity Geometry: SpatialConfiguration
entity Evidence: MeasurementOrCalculation
entity Environment: PhysicalChemicalConditions
entity BondEnergy: EnergyQuantity
entity ElectronDensity: QuantumObservable
entity HydrogenBondNetwork: InteractionGraph
entity Provenance: SourceRecord

04. TYPED RELATIONSHIPS
relation HAS_DONOR(HydrogenBond, DonorGroup)
relation HAS_HYDROGEN(HydrogenBond, HydrogenAtom)
relation HAS_ACCEPTOR(HydrogenBond, AcceptorSite)
relation CONNECTS(HydrogenBond, ChemicalEntity, ChemicalEntity)
relation HAS_GEOMETRY(HydrogenBond, Geometry)
relation SUPPORTED_BY(HydrogenBond, Evidence)
relation UNDER_CONDITIONS(HydrogenBond, Environment)
relation PART_OF_NETWORK(HydrogenBond, HydrogenBondNetwork)
relation HAS_PROVENANCE(HydrogenBond, Provenance)

05. STRUCTURAL CONSTRAINTS
constraint donor_group_contains_X_H_bond
constraint hydrogen_bond_has_donor_and_acceptor
constraint donor_and_acceptor_may_belong_to_same_molecule
constraint evidence_required_for_confirmed_status
constraint do_not_assume_all_O_H_or_N_H_contacts_are_hydrogen_bonds
constraint do_not_assume_all_hydrogen_bonds_are_linear

06. DONORS
Typical donors include O-H, N-H and F-H fragments.
Other X-H donors, including some C-H groups, can participate under suitable chemical conditions.
Donor propensity depends on electronic structure, molecular context and environment.

07. ACCEPTORS
Common acceptors include lone-pair-bearing oxygen and nitrogen sites, anions and certain pi systems.
Acceptor ability depends on charge, accessibility, resonance, protonation and environment.
An atom's element identity alone does not guarantee acceptor behaviour.

08. GEOMETRY
Let r_HY be hydrogen-to-acceptor distance.
Let theta = angle(X,H,Y).
Geometry may be described by r_XH, r_HY, r_XY and theta.
Shorter contacts and near-linear arrangements often support hydrogen bonding but are not universal necessary-and-sufficient tests.

09. ENERGETICS
DeltaE_interaction = E_complex - sum(E_isolated_fragments) under a declared computational convention.
DeltaG_association = DeltaH_association - T*DeltaS_association.
A favourable enthalpy does not by itself guarantee favourable association free energy.
Energy and geometry depend on solvent, temperature, pressure and molecular structure.

10. ELECTRONIC DESCRIPTION
Relevant contributions may include electrostatics, polarisation, dispersion and charge-transfer interactions.
No single contribution should be asserted universally dominant.
Hydrogen bonding is not equivalent to a conventional covalent X-H bond.

11. INTERMOLECULAR HYDROGEN BOND
rule intermolecular:
  if donor.molecule != acceptor.molecule and interaction_evidence
  then classify interaction as intermolecular_hydrogen_bond

12. INTRAMOLECULAR HYDROGEN BOND
rule intramolecular:
  if donor.molecule == acceptor.molecule and interaction_evidence
  then classify interaction as intramolecular_hydrogen_bond

13. WATER NETWORKS
Water can donate and accept hydrogen bonds.
Hydrogen bonding contributes to water's liquid structure and ice polymorphs.
Network topology and lifetimes depend on temperature, pressure and phase.

14. BIOLOGICAL CONTEXT
Hydrogen bonds contribute to protein secondary structure, nucleic-acid base pairing and molecular recognition.
They act alongside stacking, electrostatics, hydrophobic effects and other interactions.
A biological binding interaction must not be attributed solely to hydrogen bonds without evidence.

15. MATERIALS CONTEXT
Hydrogen bonding can influence crystal packing, polymer properties, supramolecular assembly and solubility.
Observed bulk properties emerge from multiple competing molecular interactions.

16. EXPERIMENTAL EVIDENCE
Evidence may involve diffraction-derived geometry, IR/Raman spectral changes, NMR shifts or coupling, thermodynamic measurements, and corroborating calculations.
Evidence quality varies by method; no single indicator is universally conclusive.

17. INFERENCE RULES
rule candidate_contact:
  if valid_donor and plausible_acceptor and compatible_geometry
  then status = CANDIDATE; confidence = CONDITIONAL
rule confirmed_interaction:
  if candidate_contact and independent_supporting_evidence
  then status = SUPPORTED
rule insufficient_evidence:
  if geometry_only and no_other_evidence
  then status != CONFIRMED
rule protonation_effect:
  if acceptor_site_protonated
  then recompute_acceptor_eligibility
rule environment_change:
  if solvent_or_temperature_changes
  then invalidate_unqualified_strength_claims

18. WORKED EXAMPLE: WATER DIMER
entities: H2O_A, H2O_B
X-H donor: O_A-H_A
acceptor: O_B
candidate: O_A-H_A...O_B
validation: geometry plus spectroscopic or computational evidence
classification: intermolecular hydrogen bond when supported

19. WORKED EXAMPLE: DNA BASE PAIR
entities: complementary nucleobases
candidate relations: donor_site...acceptor_site
constraint: correct base-pairing geometry and tautomer/protonation state
interpretation: hydrogen bonds contribute to pairing specificity but do not alone explain duplex stability

20. COUNTEREXAMPLES AND LIMITS
A short nonbonded contact is not automatically a hydrogen bond.
A strong hydrogen bond need not be perfectly linear.
A donor and acceptor may compete with solvent or other partners.
Gas-phase binding energies should not be substituted for solution free energies.

21. SEMANTIC EQUIVALENCE
alias: H-bond -> hydrogen bond
alias: hydrogen bonding -> hydrogen-bond interaction/process, context-dependent
not_equivalent: hydrogen bond != covalent X-H bond
not_equivalent: hydrogen bond != generic van der Waals contact
not_equivalent: donor != acceptor

22. GRAPH REPRESENTATION
node HB_001: HydrogenBond
edge HB_001 HAS_DONOR Donor_OH_001
edge HB_001 HAS_ACCEPTOR Acceptor_O_002
edge HB_001 UNDER_CONDITIONS Ambient_001
edge HB_001 SUPPORTED_BY Spectroscopy_001
edge HB_001 HAS_PROVENANCE Source_001

23. MEASUREMENT SCHEMA
measurement distance: unit angstrom or nanometre; uncertainty required
measurement angle: unit degree; uncertainty recommended
measurement energy: unit kJ/mol; specify reference state and method
measurement temperature: unit kelvin
measurement pressure: unit pascal

24. CONFIDENCE
CONFIDENCE.status: CANDIDATE | SUPPORTED | DISPUTED | REJECTED
CONFIDENCE.score: nullable calibrated number in [0,1]
CONFIDENCE.basis: provenance, method, uncertainty, reproducibility
No numeric confidence should be fabricated from conceptual rules alone.

25. VALIDATION
validate required_fields_present
validate donor_group_contains_hydrogen
validate acceptor_site_exists
validate dimensional_consistency
validate measurement_uncertainties_when_available
validate evidence_links_resolve
validate chemical_charge_and_protonation
validate source_provenance
validate no_unsupported_strength_generalisation

26. FAILURE MODES
failure geometry_only_overclaim
failure missing_solvent_context
failure incorrect_protonation
failure confusion_between_bond_energy_and_free_energy
failure conflating_inter_and_intramolecular
failure treating_model_prediction_as_experimental_observation

27. UPDATE MODEL
UPDATE_MODEL.trigger: new experimental result, revised geometry, protonation change, environmental change, corrected provenance
UPDATE_MODEL.actions: revalidate entities, re-evaluate interactions, update evidence and confidence, version graph
UPDATE_MODEL.history: retain prior assertions with timestamps and change reasons

28. FLOW HASH
FLOW_HASH.algorithm: SHA-256
FLOW_HASH.input: canonical UTF-8 representation of ontology payload excluding mutable hash field
FLOW_HASH.value: COMPUTE_ON_PUBLICATION
FLOW_HASH.note: placeholder is not a calculated digest

29. AI CONSUMPTION
AI_CONSUMPTION.format: UTF-8 text
AI_CONSUMPTION.mode: typed semantic graph and rule evaluation
AI_CONSUMPTION.require_provenance: true
AI_CONSUMPTION.require_evidence_for_confirmation: true
AI_CONSUMPTION.avoid_unqualified_generalisation: true
AI_CONSUMPTION.output: entities, relationships, evidence, assumptions, confidence, validation status

30. COMPLETENESS CHECK
required_sections: 01..30
closing_marker_required: true
scientific_status: synthesis; live source not independently verified

END FLOW ALGEBRA — HYDROGEN BOND ONTOLOGY