Heavy Metal Ion Sensing by N- (4-Styrylphenyl) iminodiacetic Acid Probe/Cyclodextrin Complexes in Water

Abstract

A N- (4-styrylphenyl) iminodiacetic acid probe 1 with a simple structure, which can be incorporated into the cyclodextrin (CyD) cavities, has been synthesized as a sensor for heavy metal ions. The UV-Vis and fluorescence analyses revealed that the probe 1 was essentially selective for Cu²⁺. The α- and β-CyDs formed stable 1: 1 complexes with 1. However, no influence was noted for the response selectivity of 1 as α- and β-CyD complexes. In contrast, although γ- CyD showed a weak binding ability for 1 without metal ions, the 2: 1 binding of 1 for heavy metal ions was evidently enhanced inside the γ- CyD cavity, resulting in the increased recognition ability for Cu²⁺, Co²⁺, Zn²⁺, and Ni²⁺. For NH₂-β-CyD possessing an additional NH₂ coordination site at the CyD rim, the 1/NH₂-β-CyD complex was found to exhibit the response selectivity for both Cu²⁺ and Ni²⁺.