Crystal Engineering of Supramolecular 1,4-Benzene Bisamides by Side-Chain Modification : Towards Tuneable Anisotropic Morphologies and Surfaces

Benzene bisamides are promising building blocks for supramolecular nano‐objects. Their functionality depends on morphology and surface properties. However, a direct link between surface properties and molecular structure itself is missing for this material class. Here, we investigate this interplay for two series of 1,4‐benzene bisamides with symmetric and asymmetric peripheral substitution. We elucidated the crystal structures, determined the nano‐object morphologies and derived the wetting behaviour of the preferentially exposed surfaces. The crystal structures were solved by combining single‐crystal and powder X‐ray diffraction, solid‐state NMR spectroscopy and computational modelling. Bulky side groups, here t‐butyl groups, serve as a structure‐directing motif into a packing pattern, which favours the formation of thin platelets. The use of slim peripheral groups on both sides, in our case linear perfluorinated, alkyl chains, self‐assemble the benzene bisamides into a second packing pattern which leads to ribbon‐like nano‐objects. For both packing types, the preferentially exposed surfaces consist of the ends of the peripheral groups. Asymmetric substitution with bulky and slim groups leads to an ordered alternating arrangement of the groups exposed to the surface. This allows the hydrophobicity of the surfaces to be gradually altered. We thus identified two leitmotifs for molecular packings of benzene bisamides providing the missing link between the molecular structure, the anisotropic morphologies and adjustable surface properties of the supramolecular nano‐objects

Highly Efficient Supramolecular Nucleating Agents for Poly(3-hexylthiophene)

Controlling the solid-state morphology of semiconducting polymers is crucial for the function and performance of optoelectronic and photonic devices. Nucleation is a commonly used and straightforward approach to tailor the solid-state morphology of semi-crystalline polymers. However, efficient nucleating agents for semiconducting polymers are still rare. Here, we present a conceptual approach to tailor supramolecular nucleating agents for the semiconducting polymer, poly(3-hexylthiophene) (P3HT). Using this approach, we developed a class of supramolecular nucleating agents, which can achieve outstanding nucleation efficiencies of more than 95% at concentrations as low as 0.1 wt %. Such efficiencies can be achieved by combining an exceptionally high epitaxial match with highly regularly arranged donor-acceptor interactions between the nucleating agent and the polymer. Notably, the supramolecular agents do not induce trap states in thin films of P3HT and are beneficial for the film stability by controlling the solid-state morphology. We anticipate that this approach can be transferred to other semi-crystalline conjugated polymers, resulting in defined solid-state morphologies

CCDC 2103040: Experimental Crystal Structure Determination

Related Article: Felix A. Wenzel, Hannes Welz, Kasper P. van der Zwan, Sebastian Stäter, Klaus Kreger, Richard Hildner, Jürgen Senker, Hans-Werner Schmid|2022|Macromolecules|55|2861|doi:10.1021/acs.macromol.1c0228