A series of crystalline solids composed of aminopyridines and succinic, fumaric, and sebacic acids

The cocrystallization of five mono- and diaminopyridines, namely 2-aminopyridine (2-AP), 2,3-diaminopyridine (2,3-DAP), 2,6-diaminopyridine (2,6-DAP), 4-aminopyridine (4-AP), and 3,4-diaminopyridine (3,4-DAP), with three dicarboxylic acids, namely, succinic (SUH2), fumaric (FUH2), and sebacic (SEH2) acids resulted in twelve organic salts including two hydrates, (2-HAP)2(SU)(SUH2) 1, (2,3-HDAP)2(SU) 2, (2,3-HDAP)2(SE) 3, (2,6-HDAP)2(FU) 4, (2,6-HDAP)2(SU) 5, (4-HAP)(SUH) 6, (4-HAP)2(FU) 7, (4-HAP)2(SE) 8, (3,4-HDAP)(SUH) 9, (3,4-HDAP)2(SE) 10, (4-HAP)2(FU)⋅2H2O 11, (4-HAP)2(SU)⋅2H2O 12. All compounds were characterized by single-crystal X-ray diffraction, IR spectra, and melting points. The proton transfer to the pyridine nitrogen in all compounds, and its location in carboxylic group in adducts with SUH2 (1, 6, and 9) were determined reliably from the low-temperature X-ray experiments. The impact of number and position of amino-groups in the pyridine molecules, as well as the conformational flexibility of the acids, and water inclusion on the final stoichiometries and supramolecular architectures is discussed.