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

b-Cyclodextrin (beta-CyD) dimer modified with two pyrene moieties, 6-(2-pyrenebutylate-aminoethyl)pyrenebutylate-amino-6-deoxy-bis(beta-CyD (beta-1) has been prepared to investigate the chemo-sensing ability for organic guests and the host-guest complexation behavior in the presence of gamma-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, Delta I-m/Delta I-m(0) and Delta I-ex/I-ex(0) were used to describe the sensing ability of beta-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 Delta I-m = I-m - I-m(0) and Delta 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 beta-1 and gamma-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, beta-1 and gamma-CyD. (c) 2005 Elsevier B.V. All rights reserved.