Mechanochemical preparation of adducts (co-crystals and molecular salts) of 1,4-diazabicyclo-[2.2.2]-octane with aromatic polycarboxylic acids

Solid-state adducts (co-crystals and molecular salts) of 1,4-diazabicyclo-[2.2.2]-octane (DABCO) with aromatic polycarboxylic acids (isophthalic acid, isoH(2), dinicotinic acid, dinH(2) and dipicolinic acid, dipH(2)) were prepared in the solid state by grinding and kneading techniques, and fully characterized via X-ray diffraction. The polycarboxylic acids differ for the presence/absence and position of a nitrogen atom in the aromatic ring; the extent of proton transfer, from the carboxylic groups on the acids to the nitrogen atoms on DABCO, reflects the trend of solution acidity of the three polycarboxylic acids.