The 187 unsubstituted parent molecules were initially optimized to the tight criteria at the ωB97X-D/def2-TZVP level with the ultrafine integration grid as implemented in the Gaussian16 package. Molecules with avoided symmetry in the ground-state structure were further optimized using explicit symmetry constraints at the same level of theory using the GAMESS 2016.1 code. Finally, the selected substituted motifs were optimized without constraint using Gaussian16. All unconstrained structures were verified to have no imaginary vibrational frequencies.