No prior knowledge is required about the crystal packing of a candidate molecule because these approaches are based on ab initio structure prediction. However, to be reliable, the CSP method must fully explore the configurational space of available crystal packings; this is a high dimensional problem including molecular positions, orientation, and unit cell dimensions, as well as flexible intramolecular degrees of freedom. The associated computational expense has meant that most applications of CSP for the discovery of functional materials have been limited to rigid molecules, where a lack of conformational freedom leads to a reduced search space. TPhP, TPyP and TBAP are conformationally flexible and in this study, we have implemented a CSP method that accurately accounts for this flexibility during structure searching, thus expanding the scope of CSP in the de novo design of functional materials. Specifically, we performed CSP calculations with TPhP, TPyP and TBAP, to determine whether these molecules were likely to form porous or π-stacked structures that could increase their photocatalytic activity for hydrogen production from water.