• OpenBabel descriptors: FP2, FP3 and FP4 (including six extended-connectivity fingerprints -ECFP 1-6) path-based fingerprints that are similar to Daylight fingerprints. We also use Spectrophores that are created from four property fields surrounding the molecules -atomic partial charges, shape deviations, lipophilicities, and electrophilicities. Since Spectrophores encode the 3-D structures of the catalysts independently of their position and orientation, structures with similar 3-D shape and properties yield similar Spectrophores.