Selective lithium ion binding involving inositol-based tris(spirotetrahydrofuranyl) ionophores: formation of a rodlike supramolecular ionic polymer from a homoditopic dimer.
The stereoselective replacement of all three hydroxyl groups in myo-inositol orthoformate by spirotetrahydrofuran rings in that manner which projects the C--O bonds in the molecular interior has been examined. The heterocyclic components were introduced sequentially, a protocol that demonstrated the utility of precomplexation to LiClO(4) as a stereocontrol tactic. The capability of 3 to coordinate to alkali metal ions was quantified. The conformationally restricted nature of this ligand conveys high selectivity for binding to lithium ion. Beyond that, the ionophore prefers to form 2:1 complexes with Li(+) and exhibits little tendency for 1:1 stoichiometry. These properties are shared by the "dimer" 36, in which two building blocks of type 3 have been conjoined by a 1,3-butadiyne tether positioned at the ortho ester terminus. This bifacial ligand reacts with one equivalent of LiClO(4) or LiBF(4) to form rodlike ionic polymers. Alternative recourse to lithium picrate results in production of the doubly capped homoditopic complex 41. Various other aspects of the chemistry peculiar to these systems are discussed.
Paquette
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Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210, USA.
Tae
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