Seventeen new 14- and 15-crown-formazans: their synthesis and evaluation in spectrophotometric determination of lithium

A number of new crown-formazans with 14 and 15 membered rings have been syn thesized, characterized and investigated as selective spectrophotometric ch elating agents for lithium. The effect of sodium ion concentration on the b ackground lithium signal was studied. A comparative study for the sensitivi ty of these new crown-formazans in spectrophotometric determinations was st udied and compared with those reported previously. The three new 14- and 15 -crown-formazans 4a-c containing the pyridyl N-oxide at the formazyl carbon showed the highest selectivity to lithium determination in the presence of sodium ion. (C) 1998 Elsevier Science B.V. All rights reserved.