(Strept)avidin as Host for Biotinylated Coordination Complexes:  Stability, Chiral Discrimination, and Cooperativity

To determine the stepwise association constants, to assess cooperativity and chiral discrimination properties of (strept)avidin toward biotinylated coordination complexes, diastereopure [Ru(bpy)₂(Biot-bpy)]²⁺ (<b>1</b>) complexes were synthesized. Analysis of the CD titration data suggests a strong cooperativity between the first and the second binding events in tetrameric (strept)avidin and a pronounced difference in affinity between avidin and streptavidin for the dicationic guest <b>1</b> as well as modest enantiodiscrimination properties with avidin as host.