How to achieve self-assembly in polar solvents based on specific interactions? Some general guidelines

In general, self-assembly in polar solutions requires a combination of several non-covalent interactions within one binding motif. Besides the combination of H-bonds and hydrophobic or aromatic stacking interactions, in the last few years H-bonded ion pairs have been proven useful in this context. Also the molecular rigidity and the extent of intra-versus intermolecular interactions within the monomer play an important role in determining the self-assembling properties of a given monomer. We present some general guidelines and illustrative examples of various approaches that have been pursued in the literature before finally concentrating on a case study from our own work, the dimerization of a guanidiniocarbonyl pyrrole carboxylate zwitterion. This zwitterion forms stable dimers with K > 10(9) M-1 in DMSO and > 10(2) M-1 even in water and can not only be used to study the importance of various non-covalent interactions for self-assembly in polar solvents but also to construct large nanostructures.