HTBZ-HOX crystallized in the monoclinic P21/c space group, with one HTBZ cation and one HOX anion in the asymmetric unit. The HOX anions were observed to form a hydrogen-bonded chain with an H⋅⋅⋅O bond distance of 1.734(1) Å. The HTBZ cations are positioned between two chains, forming strong hydrogen bonds on each side, with H⋅⋅⋅O bond distances of 1.897( ) Å and 1.799( ) Å. The arrangement of the carboxylate oxygen atoms optimally supports the formation of π-π stacked HTBZ cations in a head-to-head conformation (Figure ). These synergetic π-π interactions and appropriately positioned hydrogen bond acceptors contribute to a stable crystal packing, as illustrated in Figure .