Unique molecular recognition property of bis-pyrene-modified β-cyclodextrin dimer in collaboration with γ-cyclodextrin

Abstract

β-Cyclodextrin (β-CyD) dimer modified with two pyrene moieties, 6-(2-pyrenebutylate-aminoethyl)pyrenebutylate-amino-6-deoxy-bis-β-CyD (β-1) has been prepared to investigate the chemo-sensing ability for organic guests and the host–guest complexation behavior in the presence of γ-CyD. This fluorescent cyclodextrin dimer showed monomer and excimer emissions; the guest-induced emissions were observed as increase or decrease depending on the guest molecules. The sensing parameters, Δ I m / I m 0 and Δ I ex / I ex 0 , were used to describe the sensing ability of β-1, where I m 0 , I m, I ex and I ex 0 were fluorescence intensities of monomer and excimer emission, respectively, in the presence and absence of the guest and Δ I m = I m − I m 0 and Δ I ex = I ex − I ex 0 . This host particulary able to distinguish between ursodeoxycholic acid and chenodeoxycholic acid, which are related as diasteromer. It is observed that supramolecular association between the β-1 and γ-CyD was formed in the presence of 1-adamantanol and bisphenol A as a guest. In this work, we succeeded to make a new type of supramolecular assembly system based on hetero association between a guest, β-1 and γ-CyD.