Water pervasively influences the hydrogen bond-driven self-assembly of molecules. In Nature, for example, the folding of a polypeptide into a protein with a well-defined three-dimensional structure is strongly directed by intramolecular hydrogen bonding between the amide groups along the polymer chain. The degree of hydration of these amides is understood to have a stabilizing effect on the overall structure. The influence of water on synthetic chiral supramolecular assemblies, in particular in organic solvents, is comparatively poorly understood. We have recently been interested in the self-assembly behavior of a chiral biphenyl tetracarboxamide in organic solvents, and by serendipity we discovered that the resulting aggregates exhibit remarkable sensitivity to the concentration of water. Based on circular dichroism spectroscopy, several distinct chiral architectures are accessible as a result of an interplay between temperature and water content. Water appears to directly interact with the hydrogen bonding between amide groups of adjacent supramolecular units based on infrared spectroscopy and fluorescence measurements. These findings suggest that water can be utilized as a unique tool for controlling supramolecular chirality in synthetic systems in organic solvents.

Consequences of water content on the formation of chiral hydrogen-bonded aggregates

254th National Meeting (2017)

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