Defining space around conducting polymers: reversible protonic doping of a canopied polypyrrole.

A canopy-shaped pyrrole derivative 2 was prepared, in which a sterically demanding pendant group is juxtaposed to the pyrrole fragment to minimize interstrand pi-pi stacking interactions in the resulting polymer. Anodic polymerization of 2 afforded highly conductive poly(2), the electronic structure of which was probed by various spectroelectrochemical techniques. A limited charge delocalization within poly(2) translates into a well-defined conductivity profile, properties important for resistivity-based sensing. Notably, the bulk conductivity was precisely modulated by a rapid and reversible deprotonation and reprotonation of the polymer backbone.