Preparation and characterization of eight crystalline supramolecular salts from 4-dimethylaminopyridine and aromatic acids

Cocrystallization of the ordinarily accessible 4-dimethylaminopyridine (DMAP), with a series of aromatic acids gave a gross of eight anhydrous and hydrous multicomponent molecular salts. The eight salts have been characterised by XRD, IR and EA, their melting points were also reported. Their structural and supramolecular manners are fully evaluated. The result unveils that among all the crystals only the ring N at the DMAP moieties are protonated with the organic acids deprotonated, giving the ion pair. Apart from salt 8 , all the crystal packing is interpreted by the strong charge-assisted N-H⋯O H-bonds from the NH + and the deprotonated acidic groups. The O-H•••O H-bonds were also found at 3 – 8 . All compounds are organic salt, the cation and anion were at 1:1 for 1 – 5 and 7 - 8 , salt 6 has the ratio of 2:1. Further analysis on the crystal packing showed that a different sets of additional CH-N, CH-O/CH 3 -O, CH-S, CH 3 -CH, CH 3 -CH 3 , CH 3 -C π , CH-π/CH 3 -π, I-π, O-S, I-I and π-π contacts contribute to the stabilization and expansion of the total 2D/3D structures. For the synergism of the various weak forces these salts took homo/hetero supramolecular synthons or both.