The synthesis of functionalized nanoscale molecular rods of defined length

We report a synthetic approach to spiro-ladder oligomers of defined length and structure that form water-soluble molecular rods. We describe the synthesis of a chiral molecular building block 1 and its assembly on solid support to form flexible chains that were then rigidified by the parallel formation of several diketopiperazine rings. Two molecular rods approximately 15 and 25 A in length were synthesized containing three and five monomers, respectively. The molecular rods were easily functionalized on both ends and were shown to have high water solubility, making them compatible with biological buffers. These molecules may find use as scaffolds for the display of ligands in chemical-biology applications and as spacers and construction materials for nanoscience applications.