title: Transition metal cation separations with a resorcinarene-based amino acid stationary phase.
abstract: A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.
authors: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
authors: Na
authors: N
authors: Li
authors: Lee J
authors: LJ
authors: Allen
authors: Roger G
authors: RG
authors: Harrison
authors: John D
authors: JD
authors: Lamb
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry; D047250:Calixarenes / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D002413:Cations, Divalent / Q000302:isolation & purification; D002614:Chelating Agents / Q000737:chemistry*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D047028:Macrocyclic Compounds / Q000737:chemistry; D008670:Metals / Q000302:isolation & purification*; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D012680:Sensitivity and Specificity; D028561:Transition Elements / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D002264:Carboxylic Acids; D002413:Cations, Divalent; D002614:Chelating Agents; D047028:Macrocyclic Compounds; D008670:Metals; D028561:Transition Elements; C466160:resorcinarene; D047250:Calixarenes; D010649:Phenylalanine; D000409:Alanine