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

Abstract

Solid-state adducts (co-crystals and molecular salts) of 1,4-diazabicyclo-[2.2.2]-octane (DABCO) with aromatic polycarboxylic acids (isophthalic acid, isoH₂, dinicotinic acid, dinH₂ and dipicolinic acid, dipH₂) 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.