Established less than a decade ago, the fascinating field of two-dimensional (2D) soft materials is advancing continuously towards widespread recognition. After demonstrating the feasibility of obtaining nano-thin supramolecular sheets and morphologically related tubular objects, considerable efforts are being undertaken to explore the functional potential of soft nanosheets. Self-assembly is a major tool for the controlled formation of nanometre-sized 2D objects. In this account, we share our current understanding of the structural requirements to direct the self-assembly of water-soluble, negatively charged oligomers in 2D. The discussion covers some promising areas of utilization such as the reporting of weak mechanical perturbations, the assembly of light-harvesting antennae, the transfer of excitation energy and the polymerization of pre-organized assemblies. The systems presented in this work illustrate the potential of 2D supramolecular materials as complementary systems to their covalent counterparts.