Communication: The synthesis of polar molecular materials with designed properties is a fundamental target of materials research. Here a fully rational synthesis of polar materials from a given set of precursors (perhydrotriphenylene and three different guests) is presented. A simulation shows that varying the relative proportions of each guest permits the level of polarity to be tuned with a high degree of control. These results are fundamental to the understanding of how a complex supramolecular system self-assembles into a material with polar properties.