Tomoyasu Mani, David C. Grills and John Robert Miller
J. Am. Chem. Soc. 137, ASAP (2015).
[Find paper at ACS Publications]
Abstract:
A recently-developed instrument for time-resolved infrared detection following pulse radiolysis has been used to measure the nu(CN) IR band of the radical anion of a CN-substituted fluorene in tetrahydrofuran. Specific vibrational fre-quencies can exhibit distinct frequency shifts due to ion-pairing, which can be explained in the framework of the vi-brational Stark effect. Measurements of the ratio of free ions and ion-pairs in different electrolyte concentrations al-lowed us to obtain an association constant and free energy change for ion-pairing. This new method has the potential to probe the geometry of ion-pairing and allows the reduction potentials of molecules to be determined in the absence of electrolyte in an environment of low dielectric constant.