Induced Circular Dichroism Spectra and Chromatography by Interaction of Some Racemic Cobalt () Complexes and d-Tartrate2- in Aqueous Solution

摘要

Induced circular dichroism spectra of racemic cobalt(￥2) complexes for [Co(en)3]3+, [Co(tn)3]3+, cis-[Co(NH3)(en)2]3+[Co(￥a-ala)(en)2]2+, [Co(gly)(en)2]2+ and [Co(acac)(en)2]2+ were measured when they were dissolved in aqueous d-tartrate2- solution at room temperature. Only a single negative CD spectrum was observed for all the complexes above in visible region(400?-500nm). It was interpreted that these CD bands were attributed to the difference in interaction between ￥?-and ￥?-enantiomers with d-tartrate2-. Namely, when d-tartrate2- was added to ￥?-enantiomer and ￥?-enantiomer, it caused ￥?-enantiomer to change greatly and ￥?-enantiomer to change only slightly; combined the results proved induced circular dichroism. The enantiomer for which the eluent has a stronger affinity should be eluted faster in ion-exchange column chromatography. It is possible to predict the elution order of chromatography from the sign of the induced CD if stronger interaction of chiral anion with the complex leads to greater change in the natural CD spectrum of the complex. The elution order was in complete agreement with the prediction from the sign of the induced CD spectrum for all the measured complexes.