Metathesis Chemistry Makes Polyrotaxanes In One Pot

Using the power of the metathesis reaction, chemists have managed to prepare a polyrotaxane via a one-pot procedure (J. Am. Chem. Soc., DOI: 10.1021/ja208515r). The unusual polymer features a polyammonium chain (blue) ringed with crown ethers (red) and capped at each end with a dimethoxyarene group (green). Researchers led by Caltech’s Robert H. Grubbs orchestrated the synthesis of the mechanically interlocked polymer, discovering that it was not necessary to preassemble the acyclic dienyl ammonium moieties with the crown ethers. Rather, they found that those components would rapidly thread in solution, so all they needed to do was add the capping units and a ruthenium-based acyclic diene metathesis catalyst to form the polymer in one reaction flask. “The efficiency and ease with which these mechanically interlocked macromolecules can be assembled should facilitate rapid modulation to achieve versatile polyrotaxane architectures,” the researchers note.