Development of Sensing Agents from Kemp’s Triacid Derivatives for Metal Ions and Chiral Amines

Sensing agents for metal ions and chiral amines were preprared from the same starting material, Kemp’s triacid. Kemp’s triacid, cis, cis-1,3,5-trimethyl-1,3,5-cyclohexane tricarboxylic acid, has unique characteristics as a scaffold for sensing agents. Namely, three carboxyl groups are pointing in the same direction from a small cyclic stage. Using target specific design, the carboxyl groups were used separately to recognize the target or signal its presence. For inorganic metal ion sensing, one or two carboxyl groups were used as chelating units while the remaining carboxyl groups served as chromophore linkers. As a result, highly sensitive detection of metal ions was observed by color change from yellow to red. For example, the detection limit for Hg2+ was 4.0 x 10-6 mol dm-3 using an imide monoacid and the same detection limit was observed for Gd3+ using amide diacid. For organic amines, two of the carboxyl groups were derivatized with optically active NMR signaling units and the remaining carboxyl group was used to bind the amines. The resulting optically active diamide monoacids were shown to be useful as NMR shift reagents to determine the optical purities of several chiral amines