Structures of NaI complexes of 16-membered azo- and azoxycrown ethers. Correlation of crystal structure and carrier-doped membrane electrode selectivity

Sodium iodide complexes of 16-membered dibenzoazocrown ether (complex I) an d dibenzoazoxycrown ether (complex II) have been synthesized and their stru ctures determined by X-ray method. Stoichiometry of both complexes is 1 :1 (ligand:salt); the cation is coordinated to oxygen atoms of the oxyethylene moieties and to one nitrogen atom of azo group in the first, or to oxygen atom of the azoxy group in the last complex. Selectivities of membrane elec trodes doped with ion carriers, including 16-membered azocrown and azoxycro wn ethers have been compared and discussed mainly in terms of features of c rystal structures of carrier complexes.