Noncovalent interactions in isolated molecular aggregates: From single molecules to nanostructures

Abstract Noncovalent interactions comprise an array of long-range interactions loosely classified as hydrogen bonds and van der Waals forces. These interactions are unique since their effect spans through long distances, therefore controlling many physical and chemical processes, such as formation of aerosols, crystals, condensation or even aggregation of molecules in the star cradles. Here, we examine the differences in the aggregation processes of molecules containing two prototypical chemical groups –OH and NH2, highly abundant in organic molecules. Both groups can take part in the formation of moderate and weak hydrogen bonds, both as proton donors and acceptors. However, the electronic differences between them result in very different aggregation structures. We will show several examples of how the structure of the aggregates is a delicate balance between several types of interactions and that small modifications on the strength of a particular interaction may result in very different structures.