Cucurbit[7]uril Complexes of Crown-Ether Derived Styryl and (Bis)styryl Dyes

In this paper, we report the interaction of the CB[7] molecular container with crown ether styryl and (bis)styryl dyes 1−6. The interaction of monostyryl dyes (1 and 2) with CB[7] results in the formation of 1:1 complexes where the CB[7] molecule is located on the region of the guest encompassing the pyridinium ring, CC double bond, and a portion of the aryl ring of benzocrown ethers 1 and 2. For (bis)styryl dyes (3−5), the formation of two types of complexes with composition dye·CB[7]·dye and CB[7]·dye·CB[7] was confirmed by a combination of optical and electrospray ionization mass spectroscopy (ESI-MS) methods. In the case of (bis)styryl dye (6), both 2:1 and 1:1 compositions 6·CB[7]·6 and CB[7]·6 were formed. Complex formation is accompanied by substantial changes in the optical characteristics of the dyes and formation of long-lived excimer species. We tested the stimuli responsiveness of this system in response to metal ions. We find that the metal ions prefer to bind to the electrostatically negative ureidyl CO portals of the CB[7] rather than with the crown ether moiety of the styryl dyes.