Fluorescence enhancement of the europium(III)-thenoyltrifluoroacetone-trioctylphosphine oxide ternary complex by gadolinium(III) and its application to the determination of europium(III)

Abstract

A study of the enhancement of the fluorescence intensity of the Eulll -thenoyltrifluoroacetone (-A) -trioctylphosphine oxide (TOPO) system by Lalll, Gdlll, Lull1 and Ylll has been carried out in a colloidal-like suspension. Gadolinium(ll1) caused the largest enhancement of the fluorescence intensity. In the presence of this element the weak fluorescence of the Eulli-TTA -TOPO system was enhanced by a factor of about 18 at a pH of between 5.5 and 6.5. The excitation and emission wavelengths were 343 and 61 5 nm, respectively. The fluorescence intensity was linear up to 10-8 M of europium; the detection limit was found to be 5 x I O -I~M and the precision at 8.0 x 1 0 -1 1~ of europium was 1.4%. By stabilising the fluorescence with cetyltrimethylammonium bromide (CTAB), the Eulll -TTA -TOPO -Gd"1 system together with three other enhancing systems could be applied to the determination of trace amounts of europium in lanthanide oxides and yttrium oxide. The fluorescence intensity of the Srnlll -TTA -TOPO system was also enhanced by La"1, Gdlll, Lull1 and Ylll. The factors influencing the fluorescence enhancement are discussed and a general mechanism involving an intermolecular transfer of energy from the enhancing complex to the fluorescing complex is proposed.In solution, the ternary complexes formed by the reaction of europium or samarium with thenoyltrifluoroacetone (TTA) and certain substituted ammonium cations or neutral ligands, such as nitrogen and phosphorus oxides (L), will usually emit an intrinsic fluorescence for the metal ion when exposed to ultraviolet radiation.'-3 However, the fluorescence is seriously interfered with by other lanthanide ions and europium and samarium mutually interfere. In the past, the solvent extraction method was commonly employed for the elimination of interferences, whereas nowadays an organic solvent or a surfactant is added to the system in order to increase selectivity and sensitivity."-7 Compared with the solvent extraction method, the latter procedure is a simple and efficient means of improving the fluorimetric determination of europium and samarium. Over the last few years interest in the application of micellar systems has increased. So far, the micellar-enhanced fluorimetric method seems to be the only type of enhanced fluorimetric method available for the determination of trace amounts of lanthanide ions.Recently, it has been shown that some of the lanthanides, yttrium and the alkaline earth metal ions can enhance the intrinsic fluorescence of a lanthanide comp1ex.x-1" For example, the sensitivity and selectivity of the Eu"' -TTA -L and Sm"1 -TTA -L systems were increased by the addition of trivalent lanthanum, gadolinium, lutetium or yttrium ions; in all instances Gd"' caused the largest enhancement of the fluorescence intensity. Early in 1967, during a study of the fluorescence characteristics of the ion associate of Eu"I (or SmIrr) with TTA -H-collidine, Melenteva et al. I 1 observed that the fluorescence intensity of the system was enhanced dramatically by the addi...

Cathodic electrochemiluminescence of acetonitrile, acetonitrile–1,10‐phenanthroline and acetonitrile–ternary Eu(III) complexes at a gold electrode

“…The ECL spectra in the presence of Eu(DBM) 3 phen and Eu(TTA) 3 phen, shown in Figs 5A and 5B, demonstrated that another maximum emission peak at about 610 nm also appeared at ECL-1, in addition to the maximum emission 530 nm for ECL-1 and ECL-2 in both systems. The emission of 610 nm was identical with fluorescent characteristic peaks of Eu(DBM) 3 2− was reduced to SO 4 •− , followed by the reaction with ligand radical dianions to generate nonemissive ligand-excited states, which then underwent intramolecular energy transfer to the Eu(III) f orbitals to form the excited states Eu(III)*. We proposed that the ECL mechanism at about 610 nm may also follow the ligand-sensitization mechanism.…”

“…Eu(TTA) 3 phen was synthesized according to the following procedure. A mixture of 1.0 mmol EuCl 3 , 3.0 mmol TTA and 1.0 mmol phen was dissolved in 30 mL ethanol with a few drops of NaOH aqueous solution under vigorous stirring.…”

Luminescent Properties of Samarium (III) in the Presence of Same Tetracycline Derivatives

“…Практическое применение колюминесцен-ции связано с определением ионов Eu 3+ [4] и Sm [5,6]. Методики отличаются низким пределом обнаружения…”

Enhanced luminescence of rare-earth Tb (III) obtained by mixing of Gd (III) in a fumarate complex and intra-molecular energy transfer

“…The triplet state energy level of the organic linkers, such as fumaric acid (24034 cm −1 ), is higher than the resonance energy levels of Tb 3+ (20430 cm −1 ), therefore, the energy absorbed by the ligand can effectively transfer to Tb 3+ , thus, the luminescence efficiency of Tb 3+ ions is enhanced [30]. When the rare earth complexes composed of active rare-earth ions Tb 3+ and inert rare-earth ions (La 3+ , Y 3+ and Gd 3+ ) were grown with some organic ligands, the characteristic emission bands of active rare-earth ions Tb 3+ were enhanced greatly.…”