Proline residues solvent effects

ET rate constants in these systems decreased from a value of k i = 3.6 X 10 s for 36 to ka 50 s" for 39. Analysis of the activation parameters for these reactions demonstrated that solvent reorganization effects have a signiflcant effect in governing the distance dependence of intramolecular ET rates and that the electronic factor in these systems follows an attenuation factor of P = 0.68 A" using the through-space distance estimate of 3.12 A per residue. Unfortunately, accurate values for AH and A5 could not be obtain for the n = 4 compound (39), which was not included in the analysis. Interestingly, Schanze and Cabana [49] observed a nearly identical distance dependence of the activation parameters for ka occurring between a rhenium bipyiidyl electron acceptor and a (di-methylamino)benzoate donor across zero to two proline residues. 

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