Self-Complementary Quadruple Hydrogen-Bonding Motifs as a Functional Principle: From Dimeric Supramolecules to Supramolecular Polymers.

The self-association of individual molecules can lead to the formation of highly complex and fascinating supramolecular aggregates. However, for binding motifs which rely only on hydrogen bonds, a combination of several such weak interactions is necessary to observe self-association in solution. Systems based on four hydrogen bonds in a linear array can be obtained which efficiently aggregate at least in chloroform. Besides the physical-organic characterization of these aggregates and the factors influencing their stability, such quadruple hydrogen-bonding motifs can also be used in the field of materials science to synthesize, for the first time, supramolecular polymers through the self-association of self-complementary monomers. As the formation of noncovalent interactions is reversible and their strength depends significantly on the chemical environment (for example, solvent, temperature), the macroscopic properties of such polymers can be controlled by variation of these parameters; hence a first step towards intelligent materials with tailor-made properties is made.