The cocrystal of 4-oxopimelic acid and 4,4 '-bipyridine: polymorphism and solid-state transformations

The cocrystal of 4-oxopimelic acid and 4,4'-bipyridine was isolated in two polymorphic forms depending upon the solvent of crystallisation. Polymorphs exhibit hydrogen-bonded chains formed between the carboxyl and pyridine moieties while different packing arrangements of chains result from C-H center dot center dot center dot O interactions. Solid-state synthesis and interconversion conditions were investigated by grinding and thermal methods.