Copper (II) diamino acid complexes: Quantum chemical computations regarding diastereomeric effects on the energy of complexation

Quantum chemical calculations were used to rationalize the observed enantiodifferentiation in the complexation of alpha-amino acids to chiral Cu(II) complexes. Apart from Cu(II)-pi interactions and steric repulsions between the anchoring cholesteryl-Glu moiety and an aromatic amino acid R group, hydrogen bonding also plays a role. In fact, in the case of tryptophan, C=O...H-N hydrogen bonding between the glutamate moiety and the tryptophan N-H group compensates for the loss of intramolecular hydrogen-bonding and diminished Cu(II)-pi interactions