Redox molecular junctions are molecular conduction junctions that involvemore than one oxidation state of the molecular bridge. This property is derivedfrom the ability of the molecule to transiently localize transmittingelectrons, implying relatively weak molecule-leads coupling and, in many cases,the validity of the Marcus theory of electron transfer. Here we study theimplications of this property on the non-linear transport properties of suchjunctions. We obtain an analytical solution of the integral equations thatdescribe molecular conduction in the Marcus kinetic regime and use it indifferent physical limits to predict some important features of nonlineartransport in metal-molecule-metal junctions. In particular, conduction,rectification and negative differential resistance can be obtained in differentregimes of interplay between two different conduction channels associated withdifferent localization properties of the excess molecular charge, withoutspecific assumptions about the electronic structure of the molecular bridge.The predicted behaviors show temperature dependences typically observed in theexperiment. The validity of the proposed model and ways to test its predictionsand implement the implied control strategies are discussed
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