Synthesis and host-guest properties of multi-crown dendrimers towards sodium pertechnetate and mercury(II) chloride

Multi-crown dendrimers of four different generations have been synthesized by grafting 4, 8, 16, and 32 benzo[15]crown-5 units at the periphery of POP AM dendrimers. The binding of sodium pertechnetate and mercury(II) chloride by the multi-crown dendrimers has been studied by liquid-liquid extraction using the radioactive probes Na-22(+), (TcO4-)-Tc-99, and Hg-203(2+). The third- and fourth-generation dendrimers 3 and 4, in particular, are capable of extracting mercury(II) with high efficiency (ca, 12 Hg-II ions per dend rimer molecule, even at low generation), It has been shown that the guest m olecules investigated are preferentially encapsulated inside the dendrimers .