关键词: 桥联β-环糊精, 协同键合, 染料, 分子识别, 超分子化学

Abstract: A novel bridged bis(β-cyclodextrin) with rigid aromatic diamino tethers, 3,3′-methylenedianilino-briged-bis(6-aimino-6-deoxy-β-cyclodextrin) (2), was synthesized by the reaction of mono-[6-o-(p-tolysulfonyl)]-β-cyclodextrin with 3,3′-methylenedianiline. The inclusion complexation behaviors of native β-cyclodextrin (1) and the novel briged(β-cyclodextrin) (2) with some organic dyes, i.e., acridine red (AR), neutral red (NR), sodium 6-toluidino-2-naphthalenes- ulfonate (TNS), ammonium 8-anilino-1-naphthalenesulfonate (ANS), rhodamine B (RhB) and brilliant green (BG) were investigated at 25 ℃ in aqueous phosphate buffer solution (pH=7.20) by means of fluorescence and ultraviolet spectroscopy. The spectral titrations gave the complex stability constants (KS) and Gibbs free energy changes (ΔG0) for the stoichiometry 1∶1 inclusion complexation of hosts examined with dye molecules. The obtained results demonstrated that bis(β-cyclodextrin) 2 showed much higher binding ability and molecular selectivity toward these guest dyes than native β-cyclodextrin 1. Typically, dimmer 2 displayed the highest binding ability upon inclusion complexation with BG, affording 22.2 times higher KS value than native β-cyclodextrin. The cooperative binding ability of the bis(β-cyclodextrin) was discussed from the viewpoints of size/shape-fit interaction and multiple recognition mechanism.

Key words: Bridged bis(β-cyclodextrin), Cooperative binding, Dyes, Molecular recognition, Supramolecular chemistry