Time-resolved CIDNP as a probe of 2,2′-dipyridyl radical anion complexation with β-cyclodextrin

The photochemical reaction of 2,2′-dipyridyl (DP) with 5-sulfosalicylic acid (SSA) was studied using time-resolved CIDNP in homogeneous and β-cyclodextrin (β-CD) aqueous solutions. The degenerate electron exchange rate constant of DP radical anion with diamagnetic precursor was estimated as 1.1 × 108 M−1 s−1 from CIDNP kinetic in homogeneous solution. It was found that DP-β-CD inclusion complex formation alter the kinetics of DP polarization. For β-CD solution the drastic decreasing of nuclear relaxation time of DP radical anion was found comparing to the homogeneous solution.