Supramolecular 1D ribbons in complexes between a bicyclic-guanidine derivative and di- or monocarboxylic acids

Abstract

Zwitterionic crystalline complexes between 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), a guanidine derivative, and two dicarboxylic acids (DCAs) (oxalic acid, adipic acid) as well as a special monocarboxylic acid (glycolic acid) have been analyzed by single crystal X-ray diffraction methods. In the solid state the carboxylic acid forms a monoanion by readily transferring an acidic proton to a TBD base, resulting in formation of strong ⁺N–H⋯O⁻ hydrogen-bonded R²₂(8) ring motifs, while O–H⋯O interactions expand the network into infinite one-dimensional supramolecular chains. Numerous C_(sp3)–H⋯O interactions also contribute in crystal packing, including TBD as a weak donor and O atoms of carboxyl groups or co-crystallized water molecules as acceptors. The hydrogen bonding and crystal packing of all three complexes have been compared with the respective guanidine–carboxylate or related complexes reported previously.