Theoretical calculations based on pseudo-potentials were used to determine the structures of the complexes formed between Cu2+ ion and 2-(8-quinolinoxy) propionic acid (LR-74), which is a potent inhibitor of non-enzymatic glycation reactions. The most stable among such complexes consist of one atom of copper and two molecules of inhibitor, [Cu(LR-74)(2)], and possess a distorted octahedral geometry. In the complex containing a single molecule of inhibitor, the square planar form, [Cu(LR-74)(H2O)](+), is slightly more stable than the octahedral form, [Cu(LR-74)(H2O)(3)](+), in solution. All octahedral complexes exhibit strong Jahn-Teller distortion that results in substantially increased axial distances. (c) 2008 Elsevier B.V. All rights reserved.