CONDUCTING POLYMETALLOROTAXANES - METAL-ION MEDIATED ENHANCEMENTS IN CONDUCTIVITY AND CHARGE LOCALIZATION

In this paper we describe polymers of two metallorotaxane systems, Rot (1, M) and Rot(2, M) (M = Zn2+ or Cu1+), which are formed by complexin g a macrocyclic phenanthroline, a 5, 5'-bis([2, 2'-bithiophen]-5-yl)-2 , 2'-bipyridine (ligand 1) or 5, 5'-bis(3, 4:3', 4'-bis(ethylenedioxy) [2, 2'-bithiophen]-5-yl)-2, 2'-bipyridine (ligand 2), and Zn2+ or Cu2 ions. The corresponding polymetallorotaxanes, PolyRot(1, M) and PolyR ot(2, M), are produced by oxidative polymerization of Rot(1, M) and Ro t(2, M), The investigations of the electrochemical, conducting, and op tical properties of the metallorotaxanes and polymetallorotaxanes as w ell as related nonrotaxane polymers Poly(1) and Poly(2) are reported. The combined electrochemical and conductivity studies of PolyRot(1, M) and PolyRot(2, M) indicated that the polymetallorotaxane's redox and conducting properties were dramatically affected by the Lewis acidic a nd redox properties of the coordinated metal ions. The Lewis acidity p roduces charge localization and a redox conduction process in both pol ymetallorotaxane systems, The matching of the polymer and Cu1+/2+ coup le redox potentials in PolyRot(2, Cu) resulted in a Cu1+/2+ contributi on to conductivity. The metal-free PolyRot(1) and PolyRot(2) were prod uced by extracting the metal ions. and these polymers reversibly bound Zn2+ or Cu2+ ions in solution. The Cu2+ dopes the films of PolyRot(2) and Poly(2), which have lower oxidation potential than those of PolyR ot(1), to produce 10(6)-10(7)-fold conductivity increases, In the case of PolyRot(1) and Poly(1), the rotaxane structure was demonstrated to be key for reversible complexation of metal ions.