Catenane gel: synthesis of high molecular weight poly[2]catenanes by Sonogashira coupling polymerization

A first catenane polymer gel was obtained by Sonogashira coupling reaction of diiodo[2]catenane and 4,4′-diethynylbiphenyl. Because of the linearity and rigidity of the ethynylene group formed in the coupling reaction, the formation of undesired cyclic dimer was inhibited, and a very high molecular weight (Mn > 2.3 × 105) poly[2]catenane was synthesized. The polymer was gelated without any chemical cross-linkage and swelled in DMF.