In the crystal structure of HTBZ-HFU, HTBZ cations are self-assembled into π-π stacked columns (Figure ). The presence of a hydrogen bonding network allows the HTBZ cations to adjust their stacking distance freely, resulting in the formation of the thermodynamically most favorable packing arrangement. As expected, this stable structure exhibits relatively low solubility. Additionally, the ∆pKa between TBZ and H2FU is 1.67, which falls within the range where both a cocrystal and a salt formulation can remain stable . While salt formation is the dominant factor, an equilibrium between N-H significant increase in solubility, resulting in TBZ concentrations of 0.83(4) mg/ml (approximately 21-fold increase) and 0.88(9) mg/ml (approximately 23-fold increase), respectively. The similar enhancement in solubility observed in these two salts can be attributed to the similarities in their crystal structures and ∆pKa between the constituents. In both structures, HTBZ cations form π-π stacked columns, where the structure of the anions influences the spacing between cations. In HTBZ-HOX, HOX forms hydrogen-bonded linear chains that bind HTBZ cations at distances defined by the HOX•••HOX interactions (Figure ). In HTBZ-SAC, neighboring HTBZ cations are bonded to SAC anions on both sides, and the HTBZ•••HTBZ distance is determined by the opening angle of the saccharinate N-C-O fragment (Figure ). Furthermore, H2OX and HSAC exhibit similar acidity levels (1.23 and 1.60, respectively), readily resulting in salt formation and a comparable increase in the pH of the resulting solution.