Non-stoichiometric carbamazepine cocrystal hydrates of 3,4-/3,5-dihydroxybenzoic acids: coformer-water exchange

The cocrystallisation of carbamazepine (CBZ) with 3,4-/3,5-dihydroxybenzoic acids (34/35DHBA) with different stoichiometries formed molecular alloys, exchanging a water molecule, in their isostructural CBZ dihydrate form. Furthermore, we show a correlation between the mechanical properties of the CBZ-DHBA cocrystals with the amount of coformer present. A unique set of carbamazepine (CBZ) non-stoichiometric cocrystal hydrates with 34/35DHBA have been synthesized which are facilitated by their isostructural nature with the CBZ dihydrate, resulting in coformer-water exchange (molecular alloy).