1H-NMR studies on the self-association of chloroquine in aqueous solution |
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Authors: | N Marchettini G Valensin E Gaggelli |
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Institution: | Department of Chemistry, University of Siena, Italy. |
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Abstract: | The concentration dependences of 1H-NMR chemical shifts and spin-lattice relaxation rates were measured for chloroquine in aqueous solution. The weak self-association constant was evaluated according to a dimerization equilibrium with the formation of self-stacked adducts (Kd = 4.52 +/- 0.68 l mol-1). The motional correlation times were evaluated for the monomer and the dimer by measuring intramolecular dipolar cross-relaxation rates of aromatic vicinal protons (tau cm = 0.06 ns and tau cd = 0.26 ns). The geometry of the stacked dimer was elucidated by measuring intermolecular dipolar cross-relaxation rates and interpreted in terms of partial superposition of quinoline moieties. |
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