Shigeharu Inouye

Molecular Complexes of Tetracycline Acid Salts. V. Infrared Spectra of Tetracycline Sulfate-Complexes.

1. Structural information concerning to the binding states of crystal water, complexing agent and sulfate anion in the dα and hγ crystals are deduced from the spectral changes accompanied with partial dehydration, together with X-ray evidence. The findings include the mobility or statistical disorderness of crystal water in the dα form, and the presences of little bonded water and a monomeric complexing agent in the hγ form. 2. From the intense band near 1100cm-1 observed in all the dα crystals, it is concluded that Td symmetry of sulfate anion still holds in the dα form. The different magnitude in splitting of the sulfate band among the hγ crystals is interpreted in terms of the removal of vibrational degeneracy of v3, as a result of interaction of a sulfate anion with a complexing agent. 3. The spectral differences arising from polymorphism are shown in the cases between the dα and dβ forms and between the hγ and hδ forms.