Pyridine-2,6-dicarboxylic acid for the sensitization of europium(iii) luminescence with very long lifetimes

Abstract

Convenient and mild syntheses of two europium(III) complexes, Na[Eu(dipic) 2 $3H 2 O]$4H 2 O (dipic ¼ dipicolinate anions) and Na[Eu(dipic) 2 $phen]$H 2 O (phen ¼ 1,10-phenanthroline), were reported. These two europium(III) complexes were confirmed by 1 H NMR, FT-IR, UV-Vis spectroscopy, and elemental and lifetime analysis. Interestingly, the lifetimes were 2.31 ms and 2.38 ms for Na[Eu(dipic) 2 $3H 2 O]$4H 2 O in the solid state and in ethanol solution, respectively, though high-frequency vibrations were present in the first coordination sphere. Furthermore, the lifetime for Na[Eu(dipic) 2 $phen]$H 2 O in ethanol solution is 3.23 ms, which is the longest lifetime reported to date. The Na[Eu(dipic) 2 $phen]$H 2 O complexes exhibited a quantum yield of 36.1% in ethanol solution, which was longer than that of Na [Eu(dipic) 2 $3H 2 O]$4H 2 O. The value of the stimulated emission cross-section (s p ) for Na[Eu(dipic) 2 $phen]$ H 2 O in ethanol was very close to the values of the Nd-glass laser for practical use, which showed that it had potential application as a high-powered liquid laser medium.

Synthesis of high surface area nanostructured La2Zr2O7 by thermal decomposition of new ion pair complex precursor

“…In the infrared spectrum of the free dipic ligand, a broad and strong band around 1700 cm -1 and the band at 1330 cm -1 are assigned to C = O and CÀO stretching vibrations of the uncoordinated carboxylate group. Carboxylate bands in free dipic n(C = O) and n(C-O) are transformed into the asymmetric n as (COO), and symmetric n s (COO) stretching vibrations in the complex spectrum and as expected they are shifted after coordination to the metal ion [28,29]. In the complex, the absorption bands due to asymmetric n as and symmetric n s stretching vibrations of the carboxylate group are observed at 1624 cm -1 and 1389 cm -1 , respectively.…”

“…The electronic spectrum of the complex in 50 : 50 ethanol/aqua solutions (1·10 -5 mol·L -1 ) exhibits absorption bands below 300 nm assignable to intraligand and charge transfer transitions, Figure 2 [29,34].…”

Pyridinedicarboxylate-Tb(III) Complex-Based Luminescent Probes for ATP Monitoring

“…The main infrared absorption bands of the complexes and the assignments are listed in Table 1 (see Figure S1 for infrared spectra). All the bands involving carboxyl (–COOH) disappear [ 11 , 15 ], but the asymmetric and symmetric stretching vibration frequencies ( υ as and υ s ) of the carboxylate group (–COO – ) are observed. It is concluded that all the ligands coordinated the terbium ion through their carboxyl.…”

“…The 1 H-NMR spectrum in Figure S3(a) shows one multiplet (br, 1H) around 8.440 − 8.236 ppm which was assigned to H4 of the pyridine ring. A broad peak at 4.452 ppm (s, 2H) in Figure S3(b) was assigned to H3 and H5 of the pyridine ring, which indicates that the Tb−O and Tb ⟶ N bonds are formed in the complex [ 15 ].…”

ALD/MLD fabrication of luminescent Eu-organic hybrid thin films using different aromatic carboxylic acid components with N and O donors

“…The efficiency of the process varies with the nature of the ligand and the bonding between the ligand and the lanthanide ion. Polydentate pyridine carboxylates are particularly promising candidates as sensitizers: [5][6][7] the large lanthanide ions act as hard acids and form strong bonds with ligands having O and N donor atoms such that the resultant hybrids usually exhibit not only high thermal stabilities but also intense photoluminescence.…”