Conducting Pseudopolyrotaxanes: A Chemoresistive Response via Molecular Recognition.

The synthesis and electrochem. properties of the macrocycle-contg. polythiophene I are described. I forms a self-assembled pseudopolyrotaxane in the presence of $π$-deficient guests such as paraquat and 1,1′-bis(4-fluorobenzyl)-2,2′-bipyridyl. Pseudopolyrotaxane formation results in both an anodic shift in the oxidn. potential of the polymer as well as a significant decrease in its max. cond. (ca. 52% at 45 mM guest). This effect is completely reversible. For comparative purposes, a nonmacrocyclic model polymer was also studied and showed no significant change in max. cond. under identical conditions. The results clearly demonstrate that the chemoresistive response is a direct result of host-guest complexation. Such a chemoresistor approach is an attractive route into conducting polymer-based sensors wherein resistivity is attenuated by perturbations arising from host-guest interactions. [on SciFinder(R)]