Molecular Complexes of Tetracycline Acid Salts. II. On the Unique Clathrate-like Complexes of Tetracycline Sulfate.

Abstract

Tetracycline sulfate hydrate forms molecular addition complexes with a wide range of organic compounds containing electronegative atoms in the molecule. The complexes exist only in a solid state and to these complexes a clathrate-like structure is suggested, in which the clathrate-forming substance is tetracycline sulfate hydrate and the enclosed molecule is a complexing agent, from the following facts : The smaller molecular volume and the limiting size of the complexing agent for the complex formation, the molecular ratio of 2 : 1 for tetracycline sulfate and complexing agent, the similarity of crystal structures of the complexes, and the identity of the diffraction patterns of the complexes with that of tetracycline sulfate hydrate that crystallize only in the co-presence of certain nitrogenous compounds.