Origin of chirality in charge transfer bands of Cu(II) acidates

Abstract

Complexes of Cu(II)_with L-aminoacids have positive charge transfer bands in their CD spectra at ca. 230 nm and negative at ca. 270 nm. Examination of complexes with L-malic acid or L-1,2-diamino propane shows that the positive band is due to charge transfer from nitrogen and the negative from oxygen to copper. This sign difference is consistent with a theoretical model. The effects of added nonchiral ligands on the CD spectra in the charge transfer region are analyzed.