Adaptability of aripiprazole towards forming isostructural hydrogen bonding networks in multicomponent salts: a rare case of strong O-H•••O- ⇆ weak C-H•••O mimicry

Aripiprazole is complexed with benzoic acid (I), 2,4-dihydroxybenzoic acid (II), 2,5-dihydroxybenzoic acid (III), hydrochloric acid (IV) and salicylic acid (V). The resulting salts are characterized by single crystal X-ray diffraction, powder X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Two salts from the Cambridge Structural Database (aripiprazole nitrate and perchlorate) are included for structural comparison. Interestingly, aripiprazole forms two types of isostructural crystals with the modulation of its conformation and hydrogen bond synthons. Salts with aromatic acids engage in three-dimensional isostructural helical networks and the inorganic acid salts form two-dimensional layered networks. Remarkably, the helices mediated by strong charge assisted O-H center dot center dot center dot O- interactions are mimicked by weaker neutral C-H center dot center dot center dot O interactions in aromatic salts of aripiprazole. Our results suggest the isostructurality may be more common in multi-component systems. The salts are stable and can be potential alternatives for suitable formulation of aripiprazole.