Unravelling the limits of the transfer of asymmetry in supramolecular polymers

Abstract

Herein, we report on the chiroptical features of N-annulated perylenetetracarboxamides 1–4 in order to establish a structure–function relationship. Compounds 1–4 present a central linker, separating the aromatic core and the peripheral trialkoxybenzamide units, with a varying number of methylene groups. The self-assembling features of these tetracarboxamides have been investigated in detail by a combination of spectroscopy and microscopy techniques. The supramolecular polymerization of 1–4 occurs through the formation of a quadruple array of H-bonds between the four amide groups and the π-stacking of the N-annulated perylene to yield H-type aggregates in a cooperative manner. Notably, intramolecularly H-bonded pseudocycles are detected for compounds 1–3 that slow down their self-assembly. However, this is not the case for compound 4 that is unable to form a 10-membered H-bonded pseudocycle. Finally, we have demonstrated that only compounds 1–3 are able to show an efficient transfer of asymmetry that is not observed for compound 4. The results presented herein represent a detailed investigation on the optimal distance for point chirality to afford an efficient transfer of asymmetry that finally yields helical supramolecular polymers.