Two triazinylanilino-bridged bis(β-cyclodextrin)s were synthesized by the reactions of N,N-diethyl-4-(4,6-dichloro-1,3,5-triazin-2-yl)aniline with 6-ethylenediamino-6-deoxy-β-cyclodextrin and 6-diethylenetriamino-6-deoxy-β-cyclodextrin. The complex stability constants for the inclusion complexation of these bis(β-cyclodextrin)s with several dyes possessing different shapes and electron intensities were determined by means of fluorescence and UV-Vis titrations at 25 ℃ in phosphate buffer solution (pH 7.2). The results show that the triazinylanilino-bridged bis(β-cyclodextrin)s exhibit not only the high complex stability constants, i.e. 6～26 times higher than that of native β-cyclodextrin, for triangular guest crystal violent that possesses a larger electron intensity, but also the high molecular selectivity for crystal violent/neutral red pair (K_CV/K_NR＝23～31). Molecular dynamics studies show that the strong binding ability of triazinylanilino-bridged bis(β-cyclodextrin)s can be mainly attributed to the cooperative binding of two cyclodextrin cavities and the bridge chain, especially the p-p interactions between the triazinylaniline group in the bridge chain and the guest dye.

Key words: bridged bis(b-cyclodextrin), dye, spectral titration, cooperative binding, p-p interaction