Chemical similarity

Chemical similarity refers to the similarity of chemical elements, molecules or chemical compounds with respect to either structural or functional qualities. Various similarity metrics exist that return a score indicating the level of similarity between molecules under comparison.

Similarity searching can only be successful if molecules are represented by a suitable description of the chemical space. Descriptors of chemical space can be categorized, according to their data representation and according to the dimensionality of molecular attributes (1D, 2D or 3D) they describe. Binary fingerprints are a typical data representation for similarity searching.

Frequently used similarity metrics are simple distance measures such as Hamming and Euclidean distance, and association coefficients such as Tanimoto, Dice and Cosine coefficients. The FlowReact engine applies the most current metric, the Tanimoto coefficient for molecule comparison.