Effect of hydrogen-bonding in the development of high-affinity metal ion complexants: Polymer-bound phosphorylated cyclodextrin

摘要

In a series of phosphorylated polyols bound to a polystyrene support, the position of the FTIR band assigned to hydrogen bonding between the -OH and phosphoryl oxygen correlates with the affinity of that phosphoryl oxygen for metal ions. Polymer with phosphorylated β-cyclodextrin (pCD) ligands is now reported as a further test of this correlation. The metal ion affinity is probed with the uranyl ion. pCD is the most red-shifted of a series of five phosphorylated polyols: the strongest polyol had been phosphorylated pentaerythritol (pPE) with a band at 873 cm-1; pCD has a band at 868 cm-1. Consistent with the FTIR bands, pCD has a significantly higher affinity for the uranyl ion than pPE: the percents complexed from a 10 -4M uranyl solution in a background of 1.0N HNO_3, HC_l, and H2SO4 are 94.7%, 90.5%, and 93.6%, respectively, for pCD and 68.6%, 52.1%, and 40.1%, respectively, for pPE. This further supports the hypothesis that the strong complexing ability of phosphorylated polyols is due to activation of the phosphoryl oxygen through hydrogen bonding between the P=O and the -OH groups within the polyol.