Molecular-Level Investigation of Hydrate–Anhydrous Phase Transformations of the Dapsone Structurally Related Compound 3,3′-Diaminophenyl Sulfone

Abstract

The solid state of a novel hydrate form of 3,3′diaminophenyl sulfone (3APS_0.5H 2 Oo) as well as its temperatureinduced phase transitions is reported. On increasing the temperature, first a partial dehydration occurs, leading to the partially hydrated 3APS_0.1H 2 Oo, which then transforms into the monoclinic anhydrous form, 3APS_Am. Finally, by recrystallization of the melt 3APS_Am, a second anhydrous orthorhombic phase is obtained (3APS_Ao). This last phase transforms in 3APS_Am at a temperature between 360 and 400 K. XRD, DSC, TGA, HSM, and in silico data have been used to better understand the dehydration mechanism. With the same aim, hydration/ dehydration tests have been carried out. Finally, the dehydration behavior of 3APS_0.5H 2 O has been discussed in comparison with that of the dapsone hydrated phase 4APS_0.33H 2 Om.

The Same but Not the Same: The Case of (S)-Naproxen/cis-1-Amino-2-indanol Chiral Resolution via Diastereomeric Salt Formation

“…Choosing the most appropriate resolving agent can be tricky and time-consuming so that it is often widely empirical. X-ray diffraction, along with various thermoanalytical techniques and in silico approaches, serves as an essential tool for exploring the forces and interactions in crystal packing, − hence playing a crucial role in understanding the driving forces behind the formation of structurally related diastereomeric salts. − …”

Halogen and Hydrogen Bonding Interplay Triggered Reversible Phase Transformations through Water Release/Uptake: X-ray Powder Diffraction Studies on Halogen-Substituted 1,4-Bis(4,5-diphenyl-imidazolyl)benzene

“…For example, 3,3′-diaminophenyl sulfone (3APS) was shown to form hemihydrate (3APS_0.5H 2 O), which was transformed into anhydrate (3APS_A), upon heating, via the formation of an intermediate phase (3APS_0.1H 2 O). 24 Recently, we have shown that the as-synthesized 1,4-bis(4,5diphenyl-1H-imidazol-2-yl)benzene (BDPI) exists as a tetrahydrate for which the single crystals cannot be obtained. 25 However, the crystal structure was determined by its powder diffraction.…”

“…The dehydration process can also occur in a stepwise manner with the formation of one/multiple intermediate hydrate phases, but identification of such intermediate phases is very difficult due to the lack of stability. For example, 3,3′-diaminophenyl sulfone (3APS) was shown to form hemihydrate (3APS_0.5H 2 O), which was transformed into anhydrate (3APS_A), upon heating, via the formation of an intermediate phase (3APS_0.1H 2 O) …”