| Abstract
| - Antimalarial cationic drugs, such as chloroquine (CQ) and ferroquine (FQ), form stable dimerstructures not only in the solid state but also in solution. The short distances (3.3−3.5 Å) observed betweenthe positively charged quinolinium rings suggest that this self-association process is driven by π/π stackinginteractions. Nevertheless, the strength of these dispersive forces is likely not sufficient to overcome thestrong repulsive +/+ electrostatic effects. The question of the exact role of the environment, particularlythe solvent, is clearly raised here. Characterization of these unconventional stabilizing nonbondinginteractions which we have named +-π/+-π is therefore of great importance. In the present work, we describetheoretical calculations and NMR experiments undertaken to probe the nature and the strength of +-π/+-πinteractions occurring upon self-association of FQ and CQ molecules in water.
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