Hi @Adam-maz thanks for the contribution!

Since this relies on having a pKa value provided as part of the input, I have a hard time seeing how it is self-contained enough to be useful to the typical RDKit user.

This may be a failure of imagination on my part: what is the use case you are thinking of where a user might have SMILES for a molecule and a reliable pKa value (or prediction), but not already have the ability to calculate the CNS-MPO score?

Hello @greglandrum!! Some chemoinformatics programs (e.g. Chemdraw or Maestro Schrodinger) allow users to calculate pKa but do not offer any CNS-MPO filter. Therefore, the ready-to-use implementation of CNS-MPO in RDKit gives users the ability to easily build their own scripts to solve this problem. Additionally, I believe that implementing the CNS-MPO code is a good start for further improvement by the RDKit community.