The two-component solid forms involving 4,4'-methylene-bis(benzenamine) included both salts and co-crystals,while 4,4'methylene-bis(benzenamine) crystallized exclusively as a salt,in agreement with the differences in the pK a values.Many of the crystal structures displayed either the neutral or the ionic form of the carboxylic acid-amino heterosynthon,and the similarity in crystal structures between the neutral and the ionized molecules makes the visual distinction between a salt and co-crystal dependent on the experimental location of the acidic proton.A variety of supramolecular hydrogen bonded motifs involving interactions between the aza molecules and carboxylic acid groups are observed rather than just the O-H···N/O-H···O motif.The motifs are identical in all the two compounds analyzed showing the robustness of these supramolecular synthons.In all adducts,recognition between the constituents is established through either N-H···O and/or O-H···O/O-H···N pairwise hydrogen bonds.In all adducts,COOH functional groups available on 1 and 2 interact with the N-donor compounds.The COOH moieties in 1 forms only single N-H···O hydrogen bonds,whereas in 2,it forms pairwise O-H···N/N-H···O hydrogen bonds.The supramolecular architectures are elegant and simple,with stacking of networks in 2,but a rather complex network with a threefold interpenetration pattern was found in 1.Thermal stability of these compounds has been investigated by thermogravimetric analysis(TGA) of mass loss.
WANG LeiZHAO LeiLIU MengLIU FaQianXIAO QiangHU ZhiQiang
