Hydrogen-bonded 2D-3D supramolecular organic salts from 4-chlorobenzylamine and organic acids

Cocrystallization of the commonly available organic primary amine, 4-chlorobenzylamine, with a series of organic acids gave a total of nine molecular salts with the compositions: (4-chlorobenzylamine): (p-toluenesulfonic acid) (1) [(HL+) · (ptsa−)], (4-chlorobenzylamine): (m-chlorobenzoic acid) (2) [(HL+) · (mcba−)], (4-chlorobenzylamine): (m-nitrobenzoic acid) (3) [(HL+) · (mba−)], (4-chlorobenzylamine)2: (3-nitrophthalic acid): H2O (4) [(HL+)2 · (3-npa2-) · H2O], (4-chlorobenzylamine)2: (1,5-naphthalenedisulfonic acid) (5) [(HL+)2 · (nds2−)], (4-chlorobenzylamine): (dichloroethanoic acid) (6) [(HL+) · (dca−)], (4-chlorobenzylamine)2: (oxalic acid)2: H2O (7) [(HL+)2 · (Hoxa−)2 · H2O], (4-chlorobenzylamine): (fumaric acid): H2O (8) [(HL+) · (Hfum−) · H2O] and (4-chlorobenzylamine)2: (1,2,3,4-butane tetracarboxylic acid) (9) [(HL+)2 · (H2bta2−)]. The nine salts have been characterized by single crystal X-ray diffraction (SCRD) technique, IR and elemental analysis (EA), the melting points of all salts were also reported, and their structural and supramolecular aspects are analyzed in some detail. The result tells that among the nine investigated crystals the NH2 units in the 4-chlorobenzylamine moieties are protonated when the organic acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted N-H⋯O H-bond formation from the NH3+ and the deprotonated acidic groups. Except the N-H⋯O H-bond, the O-H⋯O H-bonds were also existed at the salts 4 and 7–9. Further analysis of the crystal packing of the salts unveiled that a distinct set of additional CH-C, CH-O/CH2-O, CH-Cl, CH2-Cl, CH-π/CH2-π, O-O, C-C, O-Cπ and Cl-Cl associations also contribute to the stabilization and extension of the total 2D-3D frameworks. For the concurrence of the manifold weak nonbonding interactions these structures adopted the homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R21(7), R42(8) and R44(12), usually appeared in organic solids of organic acids with amine, were again shown to be involved in constructing some of these H-bonding networks.