MULTIARMED MACROCYCLIC POLYAMINES EXHIBITING UNIQUE CATION-BINDING AND CATION-TRANSPORT PROPERTIES TOWARD ALKALI-METAL AND ALKALINE-EARTH-METAL CATIONS

A variety of multiarmed macrocyclic polyamines were prepared as a new type of metal carrier, in which amide-, ester-, nitrile-, and ketone-functionalized arms were attached as secondary donor sites. Extraction and C-13 NMR binding experiments revealed that their cation-binding behavior was largely dependent on the nature of the arm donor group as well as the size of the parent polyamine ring. In particular, introduction of an amide-functionalized arm into a suitable polyamine ring significantly enhanced binding ability toward "hard" metal cations, while the parent polyamine ring weakly bound these metal cations. Their unique cation-binding properties offered an effective membrane transport of hard metal cations. Since the cation-binding and -transport profiles of the new multiarmed macrocyclic polyamines differed greatly from those observed with conventional polyamines and related macrocycles, the present study provides a new possibility for designing a novel, macrocyclic polyamine type of synthetic carrier.