Silver(I) ion selective ionophores containing dithiocarbamoyl moieties on steroid backbone.

Tweezer-type and non-tweezer-type ionophores containing dithiocarbamoyl groups on a 7-deoxycholic amide or cholane derivatives were designed and synthesized. Potentiometric evaluation of the poly(vinyl chloride) (PVC) membranes containing those deoxycholic amides/cholanes linked with tweezer-type dithiocarbamoyl moieties showed excellent affinity and selectivity to silver(I) ion over alkali, alkaline earth and other transition metal cations. On the other hand, deoxycholic amides/cholanes substituted with one dithiocarbamoyl group, i.e., non-tweezer-type ionophores, resulted in relatively poor potentiometric sensitivity and detection limits. The enhanced potentiometric properties of newly synthesized tweezer-type dithiocarbamoyl containing ionophores have been further improved by employing silver ion complexing reagent in the internal reference solution, which resulted in greatly reduced detection limit ( approximately 100ppt) for the electrodes based on them.

Synthesis and characterization of 7-deoxycholic amide backbone-based silver(I) ionophores.

Four ionophores containing bipyridyl groups on a 7-deoxycholic amide derivative scaffold were designed and synthesized. Potentiometric evaluation of the Poly(vinyl chloride) (PVC) membranes containing those deoxycholic amides bearing bipyridyl moieties with a short linkage showed good affinity to silver(I) ion over alkali, alkaline earth and other transition metal cations. However, two bipyridyl groups flexibly linked to the deoxycholic frame through a long linkage do not result in appreciable potentiometric responses.

Ion-selective electrodes based on molecular tweezer-type neutral carriers.

Potentiometric properties of cholic and deoxycholic acid derivatives substituted with various ion-recognizing moieties, such as dithiocarbamate, bipyridyl, glycolic and malonic diamides, urea and thiourea, and trifluoroacetophenons (TFAP), have been studied using solvent polymeric membranes. The dithiocarbamate and bipyridyl group containing ionophores exhibit high silver ion selectivity. The cholic acid derivatized with glycolic diamides exhibited high calcium selectivity, but its complex formulation constant was 10(5) times smaller than that of ETH 1001. The reduced calcium binding ability of the glycolic diamide-substituted ionophore was advantageous for eliminating anionic interference. The bi- or tripodal malonic diamide-substituted ionophores exhibited substantially increased magnesium selectivity. Anion-selective ionophores have been designed by substituting urea and thiourea group containing chains to the hydroxyl linkers of chenodeoxycholic acid frames; their selectivity closely followed the sequence of Hoffmeister series, except the unusually large response of the thiourea-substituted ionophore to sulfate. The most successful examples of cholic or deoxycholic acid frame-based ionophores are those functionalized with two carbonate-selective TFAP groups: bipodal TFAP groups behaves like a tweezers for the incoming carbonate, and exhibit analytically interference free and quantitative responses to the carbonate in serum and seawater samples.