Crystal Structures, Thermal Degradation, and Biological Activities of Some New Ammonium and Hydrazinium Salts of Cyclohexanediaminetetraacetic Acid

Abstract

Neutralization reaction in aqueous medium between cyclohexanediaminetetraacetic acid (H4CDTA) and weak bases such as hydrazine hydrate and aqueous ammonia yielded a series of new salts such as N2H5H3CDTA.H2O, (N2H5)3HCDTA.H2O, NH4H3CDTA.2H2O, and N2H5NH4H2CDTA.H2O. The type of salt formed depends on the ratio of H4CDTA to base used and the pH of the medium. The compositions of the previous compounds were determined by hydrazine and microanalyses. The infrared spectra of the salts reveal the presence of free carboxylic acid groups. The X-ray single-crystal structures of N2H5H3CDTA and NH4H3CDTA clearly reveal that these salts exist as zwitterions in solid state. The simultaneous TG-DTA profiles show the multistep degradation with almost 100% mass loss indicating the complete decomposition. The biological screening of the aqueous solution of these salts reflects the enhanced activities of the hydrazinium salts than the free acid and the ammonium salts.