Chiral supramolecular assemblies from an achiral naphthalene diimide bearing a urea moiety.

The ordering of organic molecules in a supramolecular self-assembly determines their physical, chemical, and photonic properties. Here, we report the aggregation of two achiral naphthalene diimides (NDIs), in which phenyl moieties are linked to the NDI core via a urea subunit, leading to chiral supramolecular assemblies in THF/methylcyclohexane. Circular dichroism spectroscopic analysis of twisted ribbons deposited from solutions indicated a mixture of left- and right-handed nanostructures for one NDI, whereas only left-handed structures were observed for the other one. Furthermore, this study also shows the effect of large atoms such as iodine on the self-assembly process, which governs and controls the helicity of the produced microstructures. The supramolecular assemblies were characterized by UV/Vis, fluorescence emission, CD, SEM, and XRD techniques.