A [2]catenane displaying pirouetting motion triggered by debenzylation and locked by chloride anion recognition.

Chloride locks the rings: Debenzylation of a chloride-templated N-benzyl pyridinium catenane, allows for a 180° "pirouetting" of the rings in the resulting neutral pyridyl catenane (see scheme). The catenane may be returned to its original co-conformation by chloride recognition as evidenced in solution and in the solid state. Copyright © 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim