R1 is a divalent group selected from the groups consisting of alkylene, cycloalkylene,...http://www.google.com/patents/US5232574?utm_source=gb-gplus-sharePatent US5232574 - Polyviologen modified electrode and use thereofAdvanced Patent SearchPublication numberUS5232574 APublication typeGrantApplication numberUS 07/748,077Publication dateAug 3, 1993Filing dateAug 21, 1991Priority dateAug 21, 1990F