Ligand ΔG(int)/kcal mol⁻¹ with AT-rich DNA and ctDNA calculated by MM–GBSA.

Compd	AT-rich DNA	ctDNA
15a	−90.1	−86.0
15b	−91.7	−86.8
21a	−80.3	−65.0
21b	−81.6	−63.0