Water-soluble host-guest system from β-cyclodextrin as a fluorescent sensor for aluminium ions: synthesis and sensing studies.

In this paper, a simple small molecule (L) based on 4-(diethylamino)-2-hydroxy-benzaldehyde and carbohydrazide has been synthesized and characterized. Moreover, under ultrasonic conditions, a host-guest system with β-cyclodextrin and L was obtained. According to the hybridization process, the host-guest system showed excellent water solubility. The investigation of the fluorescence spectra revealed that the host-guest system exhibited a characteristic fluorescence behavior toward Al(3+) in a pure water environment. Upon addition of Al(3+), the host-guest system showed a strong blue fluorescence, which resulted from the fluorophore of L after the coordination of β-CD-L and Al(3+) with a high binding constant (k = 3.1626 × 10(11) M(-1)). In addition, SEM images demonstrated that the host-guest system expressed good crystallization behavior. Fluorescence microscope images of onion epidermal cells with β-CD-L-Al(3+) proved that the water-soluble host-guest system possessed a high ability for cell permeability.