Chemical space

The assumptions [3] used for estimating the number of potential pharmacologically active molecules, however, use the Lipinski rules, in particular the molecular weight limit of 500.

The estimate also restricts the chemical elements used to be Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur.

This number is often misquoted in subsequent publications to be the estimated size of the whole organic chemistry space,[4] which would be much larger if including the halogens and other elements.

As of October 2024, 219 million molecules were assigned with a Chemical Abstracts Service (CAS) Registry Number.

[12][13] Generation of chemical spaces may involve creating stoichiometric combinations of electrons and atomic nuclei to yield all possible topology isomers for the given construction principles.

View of PubChem chemical space; a projection of the 42-dimensional molecular quantum numbers (MQN) properties of compounds in PubChem (5 virtually created libraries of compounds) using PCA . Color coding is according to fraction of ring atoms in molecules (blue 0, red 1). [ 1 ]