Predicting co-crystal structures of N-halide phthalimides with 3,5-dimethylpyridine.

Crystal structure prediction (CSP) calculations were carried out to examine potential formation of co-crystals between N-halide phthalimides (Cl, Br or I) and 3,5-dimethylpyridine (35DMP). The co-crystal structure of N-bromophthalimide (nbp) with 35DMP (nbp-35DMP) is known, and the generated co-crystal structure of rank 1 is identical to experimental structure (VELXES). For the unknown crystal structure of N-iodophthalimide (nip), structure of rank 1 is suggested as a likely co-crystal structure.

The seventh blind test of crystal structure prediction: structure generation methods.

A seventh blind test of crystal structure prediction was organized by the Cambridge Crystallographic Data Centre featuring seven target systems of varying complexity: a silicon and iodine-containing molecule, a copper coordination complex, a near-rigid molecule, a cocrystal, a polymorphic small agrochemical, a highly flexible polymorphic drug candidate, and a polymorphic morpholine salt. In this first of two parts focusing on structure generation methods, many crystal structure prediction (CSP) methods performed well for the small but flexible agrochemical compound, successfully reproducing the experimentally observed crystal structures, while few groups were successful for the systems of higher complexity. A powder X-ray diffraction (PXRD) assisted exercise demonstrated the use of CSP in successfully determining a crystal structure from a low-quality PXRD pattern.