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.

A series of monomeric and homodimeric 4-alkoxystyryl(pyridinium) dyes was synthesized and their DNA-binding properties were investigated. We found that the length of the alkyl substituent has a crucial influence on the binding mode of the dyes, although the structure of the DNA-binding unit is the same for all compounds. Remarkably, mono- and bis-styryl derivatives comprising an oxodecyl chain represent the rare examples of small molecules that bind to the major groove of DNA. We have also demonstrated that the dyes, except the monostyryl dye with a bromopropyl substituent, form chiral aggregates in the presence of double-stranded DNA.

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