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 POPAM-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 ²²Na⁺, ⁹⁹TcO₄ ^-, and ²⁰³Hg²⁺. 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 dendrimer molecule, even at low generation). It has been shown that the guest molecules investigated preferentially encapsulated inside the dendrimers.