Self-assembly of tetrathiafulvalenes, their conjugated oligomers, and giant macrocyclic oligothiophenes in solution leads to important solvatochromic, thermochromic, electrochromic, and switching properties. Furthermore, based on the self-assembly in solution. various nanostructures can be constructed in the solid state to produce nanowires, nanoparticles, nanotubes, tapes, ribbons, and microcrystals. This article highlights the self-aggregation of organic pi-donors in solution and the formation of nanostructures from these pi-donors in the solid state.