IR absorption spectrophotometric analysis of the complex formed by tetracycline and synthetic hydroxyapatite

The infrared (IR) spectra of KBr pellet preparations of tetracycline (TC) complexes with hydroxyapatite (HA) indicated that the binding of the antibiotic to bone mineral can occur independently at each of two ligands. The shifts in the IR spectrum occur for the keto-enol ligand of rings B and C and for the tricarbonylmethane grouping of ring A. Analogs that lack one or the other of these groups are able to form complexes with HA in which the common portion resembles that of the parent molecule.