SDF/MOL

Item	Value
Format ID	sdf
Extensions	.sdf, .sd, .mol
Read	Yes
Write	Yes
Registry role	Reader, file writer, frame writer
Data level	Coordinates on read; graph required on write

SDF/MOL structure IO backed by RDKit graph extraction and strict graph writer semantics.

Python

from molop import AutoParser

frame = AutoParser("molecule.sdf")[0][0]
print(frame.rdmol.GetNumAtoms(), frame.rdmol.GetNumBonds())

Output

Output is atom and bond counts, for example 3 2 for water.

Arbitrary SD data fields are not guaranteed to round-trip.

Feature	Support	Scope	Limits
Reader	Supported	SDF/MOL blocks parsed into atom, coordinate, bond, formal charge, radical, total charge, and multiplicity fields.	Arbitrary SD data-field round-trip is not advertised by the tested contract.
Writer graph policy	Supported	SDF file/frame writer requires graph-capable input, defaults to strict graph semantics, and supports RDKit/OpenBabel rendering engines.	Coords-only override is rejected when no coords-only SDF writer exists.
Registry conversion	Supported	Parsed structures can be converted to SDF through the codec registry.	Conversion quality depends on recovered or transformed graph data.