Chiroptical sensing of perrhenate in aqueous media by a chiral organic cage.

A chiral cage is proposed as an effective chiroptical sensor for perrhenate (surrogate for 99 TcO 4 - ) in water, fruit juice and artificial urine media. The key mechanism for the chiroptical sensing resides in the change of dihedral angle of the binaphthyl unit and H-bonds with the guest, resulting in ample changes of the CD signal as a consequence of the binding event.