https://doi.org/10.1351/goldbook.11490
Surface area over all polar atoms (usually oxygen and nitrogen), including any attached hydrogen atoms, of a molecule.
Notes:
- Polar surface area is a commonly used metric (c.f. molecular descriptor) for the optimisation of cell permeability. Molecules with a PSA of greater than \(\pu{1.4 nm2}\) are usually poor at permeating cell membranes. For molecules to penetrate the blood-brain barrier, the polar surface area should normally be smaller than \(\pu{0.6 nm2}\), although values up to \(\pu{0.9 nm2}\) can be tolerated.
- Sometimes sulfur atoms are included in the definition.
- The value of PSA depends on the conformation of the molecule and also the algorithm and atomic radii used in the calculation.
See also: topological polar surface area (TPSA)