Crystal engineering of supramolecular 1,4-benzene bisamides by side chain modification - towards tuneable anisotropic morphologies and surfaces

Chemphyschem. 2021 Oct 13. doi: 10.1002/cphc.202100597. Online ahead of print.ABSTRACTBenzene bisamides are promising building blocks for supramolecular nanoobjects. 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 using NMR crystallographic strategies, determined the nanoobject morphologies and derived the wetting behaviour of the preferentially exposed surfaces. 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 nanoobjects. 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 a...
Source: Chemphyschem - Category: Chemistry Authors: Source Type: research