A Systematic Study of the Photophysical Processes in Polydentate Triphenylene-Functionalized Eu³⁺, Tb³⁺, Nd³⁺, Yb³⁺, and Er³⁺ Complexes

Abstract

m-Terphenyl-based lanthanide complexes functionalized with a triphenylene antenna chromophore ((Ln)1) exhibit sensitized visible and near-infrared emission upon photoexcitation of the triphenylene antenna at 310 nm. Luminescence lifetime measurements of the (Eu)1 and (Tb)1 complexes in methanol-h 1 and methanol-d 1 revealed that one methanol molecule is coordinated to the lanthanide ion, indicating that all eight donor atoms provided by the ligand are involved in the encapsulation of the lanthanide ion. The luminescence lifetimes of the near-IR-emitting complexes (Er)1, (Nd)1, and (Yb)1 in DMSO-h 6 and DMSO-d 6 are in the microsecond range, and are dominated by nonradiative deactivation of the luminescent state. The processes preceding the lanthanide luminescence in the sensitization process have been studied in detail. The complexed lanthanide ion reduces the antenna fluorescence and increases the intersystem crossing rate via an external heavy atom effect. The subsequent energy-transfer process was found to take place via the antenna triplet state in all complexes. Luminescence quantum yield measurements and transient absorption spectroscopy indicated that in solution two conformational isomers of the complexes exist: one in which no energy transfer takes place, and one in which the energy transfer does take place, resulting in the lanthanide luminescence. The intramolecular energy-transfer rate is higher in the (Eu)1 and (Tb)1 complexes than in the near-infraredemitting complexes. In methanol the energy-transfer rate is 3.8 × 10 7 s -1 for (Eu)1 and (Tb)1. In DMSO-d 6 the intramolecular energy-transfer rate is higher in the (Nd)1 complex (1.3 × 10 7 s -1 ) than in the (Er)1 (3.8 × 10 6 s -1 ) and (Yb)1 (4.9 × 10 6 s -1 ) complexes.

Visible and Near-Infrared Luminescence of Lanthanide-Containing Dimetallic Triple-Stranded Helicates: Energy Transfer Mechanisms in the SmIII and YbIII Molecular Edifices

“…The lifetime of the Yb( 2 F 5/2 ) state is long in D 2 O, 40 µs (Table 2) compared to solution data reported previously, e.g., 18.6 µs in DMSO-d 6 for a m-terphenyl-based complex bearing a triphenylene chromophore 38 and 6.2 µs in D 2 O for a complex with a chiral macrocyclic tetra-amide. 39 As a result, the quantum yield of the metal-centered luminescence amounts to 1.8% (D 2 O) upon ligand excitation which, again is fairly large compared with the values reported in the literature for other Yb III complexes, e.g., 0.45% for the complex with fluorexon in D 2 O 40 or 0.5% for a terphenyl-based complex in DMSO.…”

Ionic liquid as plasticizer for europium(iii)-doped luminescent poly(methyl methacrylate) films

“…8,9 Typical applications of such polymer films are in organic light emitting diodes (OLEDs) [10][11][12][13][14] or in active optical polymer fibers for data transmission. [15][16][17] A popular polymer matrix for use as host for luminescent lanthanide complexes is poly-(methyl methacrylate) (PMMA), which is transparent at wavelengths longer than 250 nm. 18 The first experiments on optical materials based on PMMA doped with b-diketonate complexes go back to the 1960's when the lanthanide b-diketonates have been tested as active components in chelate lasers.…”

Preparation, Crystal structure and Luminescence Properties of Lanthanide Complexes with 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine and Organic Carboxylic Acid

“…The two bands shifted to 1383-1382 and 1012-1008 cm −1 in the Crystal complexes 1-5, respectively, indicating that nitrogen atoms of the center ring and the pyridyl ring were coordinated with the metal ions [15,16]. The bands observed in the 767-771 cm −1 region were assigned to the aromatic C-H deformation vibrations [15,35]. In addition, the complexes 1-4 exhibited a band in the 1645-1623 cm −1 region, which could be assigned to δ (OH) of H 2 O [35].…”

“…For TPTZ ligand, the band at 1370 cm −1 was attributed to the breathing vibration of the center ring and the band at 993 cm −1 was attributed to the bending vibration of the pyridyl ring. The two bands shifted to 1383-1382 and 1012-1008 cm −1 in the Crystal complexes 1-5, respectively, indicating that nitrogen atoms of the center ring and the pyridyl ring were coordinated with the metal ions [15,16]. The bands observed in the 767-771 cm −1 region were assigned to the aromatic C-H deformation vibrations [15,35].…”