Color-coded MQN-maps of subsets GDB-13-FL and ZINC.FL. A. Loadings of PC1, PC2 and PC3 for PCA of FragranceDB. The 42 MQNs are defined as follows: atom counts: c, f, cl, br, i, s, p = elements, an/cn = acyclic/cyclic nitrogens, ao/co = acyclic/cyclic oxygens, hac = heavy atom count, bond counts: asb/adb/atb = acyclic single/double/triple bonds, csb/cdb/ctb = cyclic single/double/triple bonds, rbc = rotatable bond count, polarity counts: hba/hbd/hbam/hbdm = H-bond acceptor/donor atoms/sites, pos/neg = positive/negative charges at pH 7.4, topology counts: asv/adv/atv/aqv = acyclic monovalent/divalent/trivalent/tetravalent nodes, cdv/ctv/cqv = cyclic divalent/trivalent/tetravalent nodes, ri = i-membered rings (i = 3-9), rg10 = ≥10-membered rings, afr/bfr = atoms/bonds shared by fused rings. ri, rg10 and afr/bfr are counted in the smallest set of smallest rings.B. Color-coded maps for GDB-13.FL. Note that the carbon count decreases at right because heteroatom rich compounds take over. C. Color-coded maps for ZINC.FL. Color-coding represents the increasing value of the indicated property in the scale blue-cyan-green-yellow-orange-red-magenta. Interactive color-coded MQN-maps for all FL subsets can be accessed with the FL-mapplet at http://gdb.unibe.ch.