Solving molecular crystal structures from X-ray powder diffraction data: the challenges posed by gamma-carbamazepine and chlorothiazide N,N,-dimethylformamide (1/2) solvate.

The crystal structures of gamma-carbamazepine (P1, Z' = 4) and chlorothiazide N,N-dimethylformamide solvate (1/2) (P2(1)/c, Z' = 2) have been determined from synchrotron and laboratory X-ray powder diffraction data, respectively, using simulated annealing. Both structures represent a significant challenge for global optimization and the successful solutions and subsequent refinements highlight the ever-expanding range of applicability of powder diffraction to structural problems of pharmaceutical relevance.