Potential propelling and rotating functions of propeller-type complexes. I. Preparation and molecular dynamics simulation of tris( S -2,3-diaminopropionato)cobalt(III)

Four optically active geometric isomers of tris(S-2,3-diaminopropionato)cobalt(III) were prepared and separated by ion-exchange column chromatography on SP-Sephadex (C-25). The identification of the four diastereomers is based on the elution order of the complexes, elemental analysis, electronic spectra, circular dichroism spectra, C-13 NMR spectra, X-ray structure analysis and comparison of these properties with those of analogous series consisting of three isomers of the bis(S-2,3-diaminopropionato)cobalt(III) ion. Structure optimization and molecular dynamics (MD) simulation of the system, consisting of the propeller-type complex fac-tris(S-2,3-diaminopropionato)cobalt(III) and 240 water molecules, were performed using AMBER 6. The results of the MD simulation suggest that distinct propelling and rotating behavior can be obtained in this complex in aqueous solution.