RESUMO
We report that three-component systems comprising styryl dyes (1 or 2) and two hosts (hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and cucurbit[7]uril (CB[7])) undergo photoinduced transformation and translocation of the styryl guest from the cavity of HP-ß-CD to CB[7]. We find that the protonation of guest trans-1 or the addition of Ba(2+) as competitor for CB[7] triggers dissociation of the container-guest complexes.
RESUMO
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.
