CO2 Promoted Gel Formation of Hydrazine, Monomethylhydrazine, and Ethylenediamine: Structures and Properties

Hydrazine, monomethylhydrazine, and ethylenediamine react readily and reversibly with carbon dioxide to form hydrazinium carboxylate, monomethylhydrazinium carboxylate, and ammonium carbamate adducts, respectively. These adducts act as low molecular weight gelators, which self-assemble and in doing so trap unreacted hydrazine or diamine. The properties and molecular structures of the gels were investigated by means of elemental analysis, DSC/TGA, heteronuclear NMR (H-1, N-15, and C-13), diffusion-ordered NMR spectroscopy (DOSY), and cryo-immobilized high resolution scanning electron microscopy (cryo-HRSEM). These complementary techniques provided the foundation for developing a pictorial representation of the bulk gel structures on the molecular level.