Inhibition of one-electron oxidation of 1-pyrenesulfonate included in cyclodextrin by sulfate radical anion

Inhibition of one-electron oxidation of 1-pyrenesulfonate (PySA−) included in cyclodextrins by sulfate radical anion (SO4−) occurred to give PySA− radical cation (Py+SA−) with a peak at 455 nm during the pulse radiolysis of a mixture of PySA−, potassium peroxodisulfate, and t-butanol. PySA− is partly included in β-cyclodextrins (βCD) to form a PySA−/βCD complex, while it exists only as a 2:2-inclusion complex, (PySA−)2/(γCD)2 in γCD. The oxidation of PySA− by SO4−was completely inhibited in βCD and γCD. This is explained by the shielding effect of CDs on the bimolecular collisional process of PySA− and (PySA−)2 in CDs with SO4−.