Highly Selective Luminescence Determination of Terbium at the Sub-ppb Level with Sulfonylcalix[4]arene-p-tetrasulfonate

Abstract

The energy-transfer luminescence of complexes of Tb3+ with calix- (CAS), thiacalix- (TCAS), and sulfonylcalix[4]arene-p-tetrasulfonates (SO2CAS), in which four p-phenolsulfonates are jointed by –CH2–, –S–, and –SO2–, respectively, was applied to an ultratrace determination of the Tb3+ ion. Based on the complexation behavior of each calix ligand, a determination procedure was established. A time-resolved measurement was conveniently employed to separate the background fluorescence from the luminescence of the calix-Tb3+ complexes. An improved sensitivity was attained by sulfur-bridged calixes, TCAS and SO2CAS, as compared to CAS, owing to the photophysical properties of the Tb3+-complexes. The detection limits for Tb3+ ion by CAS, TCAS, and SO2CAS ligands were estimated to be 8.2×10−10 mol dm−3 (131 ppt), 2.0 × 10−10 mol dm−3 (32 ppt), and 2.3 × 10−10 mol dm−3 (37 ppt) at S/N = 3, respectively. In terms of the selectivity, the effect of diverse coexisting ions on the luminescence intensity of the Tb3+ complexes was studied. The luminescence of the TCAS complex was interfered by the presence of a 5-fold amount of other lanthanide ions, while that of the SO2CAS complex was more tolerant for those metal ions, allowing the presence of as much as 50 to 100-fold amounts. Also, 10 to 1500-fold amounts of other common ions were tolerated by using SO2CAS. Thus, SO2CAS was proved to be a practical reagent for determining the Tb3+ ion at the sub-ppb level.

Chemistry of Thiacalixarenes

“…[94] Moreover, 62a can almost completely remove traces of halogenated compounds from water, [95] which is very attractive from an ecological point of view. Several other applications, such as the use as a stationary phase for gas chromatography, [96] a specific pre-column chelating agent for Ni II in KD HPLC, [97] a chelating adsorbent for heavy metal ions, [98] a highly selective means for the luminescence determination of terbium, [99] and in the construction of ion-sensors [100] or self-assembled monolayers [101Ϫ104] have also been reported. …”

Reactions of heteroaromatic chromophores with lanthanide complexes of p-sulfonatothiacalix[4]arene

“…10 In addition, a Tb III complex with TCAS exhibits pH dependent emission properties. 12, 15 For the above rea sons, these techniques were used to examine equilibria in aqueous solutions of [Ln(L) n ] 3+ -TCAS, where Ln = La, Gd, Tb, and Yb; L = bipy, phen, and terpy; n = 2 (for bipy and phen) and 1 (for terpy).…”

“…[9][10][11][12][13][14] Sulfur and sulfonyl analogs are of particular interest be cause they form pH dependent luminescent complexes with lanthanide ions. 12, 15 For instance, lanthanide ions are efficiently bound by p sulfonatothiacalix [4]arene (TCAS, [H 4 X]Na 4 ) through either the sulfonate groups of the upper rim in acidic media (pH 2) 7 or the electron donating groups of the lower rim in neutral and weakly basic media. 10, 12 The polytopic character of the calixarene platform enables simultaneous binding of a luminescent ion and a ligand.…”

Investigation of the Supramolecular Assembly of Luminescent Lanthanide Nanoparticles Surface Functionalized by p‐Sulfonato‐Calix[4]arenes with Charged Aromatic Compounds

“…They were synthesized starting from p-tert-butylphenol according to protocols described in the literature. [8,12,[22][23][24][25][26][27][28] 1 H and 13 C NMR spectra of C [4], SC [4] and SO 2 C [4] are shown in Figures S2 to S7.…”

“…[11] Water soluble Tb complexes of p-sulfonatocalixarene derivatives have been reported to be more luminescent than their Pr, Sm, Eu and Dy counterparts, [12] the very high affinity of the ligand towards Tb ions allowing the detection of this cation at the subppb level in aqueous solution. [13] Encapsulation of Tb complexes of p-sulfonatothiacalix [4]arene in silica nanoparticles (NPs) led to an enhanced luminescence emission, illustrating the significant input of nanoscience in the search of designing brighter probes. [14] Calixarenes are also widely used as supramolecular host modules for molecular recognition, as their hydrophobic cavities can host charged and neutral guests such as solvent molecules, [15] pesticides, [16] and biorelevant compounds (dopamine, testosterone…).…”