2 research outputs found
Plasticity in zwitterionic drugs: the bending properties of pregabalin and gabapentin and their hydrates
The investigation of mechanical properties in molecular crystals is emerging as a
novel area of interest in crystal engineering. Indeed, good mechanical properties
are required to manufacture pharmaceutical and technologically relevant
substances into usable products. In such endeavour, bendable single crystals
help to correlate microscopic structure to macroscopic properties for potential
design. The hydrate forms of two anticonvulsant zwitterionic drugs, Pregabalin
and Gabapentin, are two examples of crystalline materials that show
macroscopic plasticity. The direct comparison of these structures with those of
their anhydrous counterparts, which are brittle, suggests that the presence of
water is critical for plasticity. In contrast, structural features such as molecular
packing and anisotropic distribution of strong and weak interactions seem less
important
Diversity in a simple co-crystal: racemic and kryptoracemic behaviour
The crystal structure containing (+/-)-3-methyl-2-phenylbutyramide with salicylic acid is the first example of a kryptoracemate co-crystal. It exhibits the first temperature mediated reversible single-crystal to single-crystal transition between two kryptoracemate forms, in addition to crystallising in another, racemic, form. Theoretical calculations and structural analysis reveal that there are only small differences in both energy and packing arrangements between the three forms. These results suggest that co-crystals can be an opportunity to investigate kryptoracemate behaviour.The crystal structure containing (+/-)-3-methyl-2-phenylbutyramide with salicylic acid is the first example of a kryptoracemate co-crystal. It exhibits the first temperature mediated reversible single-crystal to single-crystal transition between two kryptoracemate forms, in addition to crystallising in another, racemic, form. Theoretical calculations and structural analysis reveal that there are only small differences in both energy and packing arrangements between the three forms. These results suggest that co-crystals can be an opportunity to investigate kryptoracemate behaviour