Concerning the selection of crystallization modifiers for non-hydrogen bonded systems: the case of benzophenone

Abstract

A design strategy for the selection of crystal growth modifiers for non-polar crystals is proposed and its application demonstrated for the case of benzophenone. The strongest intermolecular interaction in the crystal structure of the stable form of benzophenone combines two strong phenyl–phenyl approaches, which embody screw symmetry along the x-axis. Two of the nine additives selected to disrupt this interaction were successful in modifying the morphology and decreasing crystal growth rates of benzophenone crystals. This efficacy is discussed and interpreted in the light of the crystal structures of the additives, which display a great variety of phenyl⋯phenyl approaches and associated symmetries. As part of this study we made use of the idea of ‘favourable connections’, based on a simple geometric method, to reveal ‘symthons’: symmetry-forming phenyl–phenyl approaches.