Circular Dichroism Studies on the Formation of Complexes of (-)-7-Chlorotetracycline with Vanadium, Chromium, and Cobalt

摘要

The complex formation of the chiral antibiotic (-)-7-chlorotetracycline ((-)-CTC) with VO(IV), Cr(III), and Co(II) in methanol/water (80:20v/v) was studied using circular dichroism. The ligand forms soluble complexes of the composition [Vo((-)-CTC)_3]~(2+), [Cr((-)-CTC)(H_2O)_4]~(3+), and [Co((-)-CTC)_2(H_2O)_2]~(2+) as predominat species in acidic solution (aH=3.2-4.9). The CD spectra of the complex ions are interpreted and their formation constants are reported.