Solvent-induced effects: self-association of positively charged pi systems.
Antimalarial cationic drugs, such as chloroquine (CQ) and ferroquine (FQ), form stable dimer structures not only in the solid state but also in solution. The short distances (3.3-3.5 A) observed between the positively charged quinolinium rings suggest that this self-association process is driven by pi/pi stacking interactions. Nevertheless, the strength of these dispersive forces is likely not sufficient to overcome the strong repulsive +/+ electrostatic effects. The question of the exact role of the environment, particularly the solvent, is clearly raised here. Characterization of these unconventional stabilizing nonbonding interactions which we have named +-pi/+-pi is therefore of great importance. In the present work, we describe theoretical calculations and NMR experiments undertaken to probe the nature and the strength of +-pi/+-pi interactions occurring upon self-association of FQ and CQ molecules in water.
Buisine
Eric
E
Laboratoire de Chimie Organique et Macromoléculaire, UMR CNRS 8009, Université des Sciences et Technologies, B.P. 90108, 59652, Villeneuve d'Ascq cedex, France.
de Villiers
Katherine
K
Egan
Timothy J
TJ
Biot
Christophe
C