Tetramorphism of fananserine : p, T diagram and stability hierarchy from crystal structure determinations and thermodynamic studies

The structures of four crystalline phases of fananserine have been solved and their melting properties determined. The p-T diagram for this tetramorphism has been constructed by combining these data. Three out of the four solids are associated with stable p-Tdomains. Two of them have a low-pressure enantiotropic character in narrow p-T domains. The fourth one is intrinsically metastable. The stability ranking agrees with that inferred from solubility measurements at room temperature.