An important goal in supramolecular chemistry is the development of stimuli-responsive systems in which supramolecular assembly is controlled by external signals. One way to do this is to use electron transfer to perturb the strength of H-bonds. The principle is straightforward: reduction that increases negative charge on a H-acceptor (A) or oxidation that increases positive charge on a H-donor (D) will increase the strength of a H-bond. However, oxidation or reduction can also lead to full proton transfer, resulting in an increase in unfavorable secondary interactions that counteracts the effect of the initial electron transfer. But, with proper design, proton transfer can lead to an increase in favorable secondary interactions, enhancing the effect of the initial electron transfer. The success of the latter strategy is demonstrated with the 3 H-bond DAD array, 1, that contains a N-methyl-4,4'-bipyridinium redox couple.1 In CH2Cl2, 1 forms a three H-bond dimer with ADA array, 2, with a modest Kb of 500 M−1 due to the unfavorable secondary interactions. Initial CV studies show that two electron reduction of the bipyridinium increases the binding strength by 2×105 giving a very strong Kb of ~108 M−1. This value is consistent with expectations for a DDD-AAA H-bond complex, strongly suggesting that electron transfer not only creates an ionic H-bond but also leads to proton transfer and conversion of the secondary interactions from unfavorable to favorable. In this presentation, the results of a full investigation of this system will be reported, including UV-vis spectroelectrochemical studies that support proton transfer and NMR studies of possible 1-1 and 2-2 homodimerization. Furthermore, theoretical CV’s that include, if needed, homodimerization will be fit to the experimental CV’s to provide a more exact measure of the binding enhancement in this system. 1H. Choi, K. Baek, S. Toenjes, J. L. Gustafson, and D. K. Smith, J. Am. Chem. Soc. 2020, 142, 17271-17276. DOI: 10.1021/jacs.0c07841 Figure 1