Figure . A schematic of DEL library members. All DEL library members in this study are composed of three small molecule building blocks and referred to as trisynthons. The first added building block is closest to the DNA (position 1) and the last added is furthest (position 3). Each building block has a corresponding DNA tag encoding its identity, shown in this figure via color coordination. The combined DNA tags form a unique barcode, which is amplified and sequenced in experiment to verify the presence of the trisynthon. Pictured is position 1 (blue), position 2 (orange) and position 3 (green), which we refer to as p 1 , p 2 and p 3 , respectively.