Fused core 86 appeared in over 40% of fused-core NFAs. This unit is extremely similar to the central unit of star performer Y6, except that it contains a phenyl instead of a branched side chain. Examination of the most frequent fused units (ESI Fig. ) unveils all top 10 have the Y-structure motif. Eight of these units contain a benzothiadiazole unit, with 113 containing a benzotriazole unit.