Buy article online - an online subscription or single-article purchase is required to access this article.
organic compounds
The title compound, C18H30N4O12, exists as an unsymmetrical tri-zwitterion. The protonated N atoms form intramolecular hydrogen bonds to carboxylate O atoms. The molecules are linked by strong intermolecular hydrogen bonds formed by three COOH groups at one end of the molecule and three carboxylates at the negative ends of the two nearest neighbors [OH 1.45 (3) Å]. The C—N bond lengths are clearly differentiated with respect to the charge on the N atom [C—N 1.459 (6), C—NH+ 1.502 (9) Å].