Fluorine in medicinal chemistry: β-fluorination of peripheral pyrrolidines attached to acridine ligands affects their interactions with G-quadruplex DNA.

Comparative X-ray structure studies reveal that C-F bond incorporation into the peripheral pyrrolidine moieties of the G-quadruplex DNA binding ligand BSU6039 leads to a distinct pyrrolidine ring conformation, relative to the non-fluorinated analogue, and with a different binding mode involving reversal of the pyrrolidinium N(+)-H orientation.