Crystal structure of 7-phenyl-7-(2,4,5-trimethyl-3,6-dioxo-cyclo-hexa-1,4-dien-1-yl)hepta-noate 1,3-dihy-droxy-2-(hy-droxy-meth-yl)propan-2-aminium monohydrate: a new solid form of seratrodast.

In the title hydrated salt, C4H12NO3 (+)·C22H25O4 (-)·H2O, seratrodast [systematic name: 7-phenyl-7-(2,4,5-trimethyl-3,6-dioxo-cyclo-hexa-1,4-dien-1-yl)hepta-noic acid] crystallized with trometamol [systematic name: 2-amino-2-(hydroxyméth-yl)propane-1,3-diol] to form a monohydrated salt form of seratrodast. The carb-oxy-lic acid group of seratrodast has transferred its proton to the amino N atom of trometamol. In the crystal, the trometamol cations are linked to the water mol-ecules and to each other by N-H⋯O and O-H⋯O hydrogen bonds forming sheets parallel to (100). The seratrodast anions are linked to both sides of these sheets by O-H⋯O and C-H⋯O hydrogen bonds, forming a three-layer two-dimensional structure. After forming the title salt, the solubility of seratrodast was found to be greatly improved.