Scheme 1. Synthetic Scheme for QT Prodrug Dimers (n = 2–8) (1–7).

Dimers were named according to the number of methylene (−CH₂−) groups located between the ester bonds, e.g., n = 2 is QT₂C₂ (1). All dimers were synthesized using dicarboxylic acid linkers and were purified to >95% by reverse phase HPLC. The pure compounds were characterized by MALDI-TOF mass spectrometry.