Molecular materials are challenging to design from scratch since the packing arrangements are based on a balance of the interplay of subtle soft intermolecular interactions. The specific packing arrangement a molecular material adopts determines its properties. Rational material design aims to create new materials with tailored properties (e.g. charge-carrier mobility) but is hampered by the difficulty to predict the most stable solid-state structure for a given molecule theoretically and to obtain it experimentally. Once the structure prediction problem is resolved, structure-property relationships for each polymorph can be obtained.

This thesis predicts structure-property relationships of helicenes to assesses their organic semiconductor (OSC) suitability.
First, two 2,2'-disubstituted [6]helicenes were computationally predicted to investigate the structure-property relationship of functionalised [6]helicenes arranging in (homo)chiral columns. The crystal structure prediction (CSP) results were analysed with respect to the accuracy of the methodology, the (dis)similarity of the crystal packing arrangements obtained across the CSP landscapes, and its charge transport properties.

Second, a dimer-based screening approach to assess the suitability of ~1,300 of terminally substituted [6]helicenes for their suitability as n-type OSC was developed and the screening results are presented.
By applying CSP to the most promising molecules, the presence of the dimer motif used at the screening stage was confirmed.
Furthermore, fluorination significantly improved electron transport in the molecular crystal by up to 200%, while side groups containing triple bonds largely lead to improved transfer integrals.

Finally, CSP was performed for naphthalene and helicenes of varying helicene length n (n = 3-12).
Thousands of crystal structures were assessed for their degree of π-π, C-H··π stacking and the degree of parallel alignment of the long helical axes. It is found that helicenes more frequently arrange in parallel to each other as the helicene length n increases, supposedly enhancing the formation of homochiral columnar packing arrangements.