Influence of the Metal Ion on the Two‐Photon Absorption Properties of Lanthanide Complexes Including Near‐IR Emitters

Abstract

The synthesis of tris(2-thenoyltrifluoroacetonate)lanthanide(III) complexes featuring a diethylaminostyryl-2,2'-bipyridine coligand was achieved for lanthanum; the near-infrared (NIR) emitters neodymium, erbium, and ytterbium; and the transition-metal yttrium. The photophysical properties were thoroughly studied, and it was demonstrated that the conjugated bipyridine ligand acts as a good antenna for the sensitization of the NIR emitters. The two-photon absorption (TPA) properties of all five complexes were investigated by using both two-photon excited fluorescence and the Z-scan method. We demonstrate that the nature of the rare earth ion has almost no influence on the TPA properties centered on the conjugated bipyridyl ligand. Finally, we show that Yb(III) is sensitized by a two-photon antenna effect, and that Nd(III) is mostly sensitized by a one-photon process involving direct excitation of forbidden f-f transitions.

Luminescence and Single‐Molecule‐Magnet Behaviour in Lanthanide Coordination Complexes Involving Benzothiazole‐Based Tetrathiafulvalene Ligands

“…Thus, the value of 591 cm -1 seems to correspond to a quite low symmetry, in agreement with the distortion induced by the two nitrogen atoms and six oxygen atoms as first neighbours of the Yb III ion in 5. [56] The perfect monoexponential fit of the luminescence decay plot confirms the purity of the sample and corresponds to a lifetime value of 8 μs at room temperature (Figure 9c).…”

NIR‐to‐NIR Two‐Photon Scanning Laser Microscopy Imaging of Single Nanoparticles Doped by YbIII Complexes

“…4 I 11/2 (1064 nm) transitions, 4 F 3/2 ! This behaviour has been already observed foro ther NIR emitting complexes [26] and in the case of the europium tris(dipicolinate) complexu pon 532 nm excitation. It is worth noting that the differencei nt erms of relative intensity of the emission bands using one-or two-photon excitationi sd ue to poor sensitivity and the absence of correction of the detector used in our two-photons et-up above 1000 nm.…”

“…It is worth noting that the differencei nt erms of relative intensity of the emission bands using one-or two-photon excitationi sd ue to poor sensitivity and the absence of correction of the detector used in our two-photons et-up above 1000 nm. [26] Consequently, the two-photon cross-section of [NBu 4 ] 3 [YbL 3 ]c an be approximated using that of the lutetium analogous measured at about 300 GM at 740 nm in dichloromethane solution ( Figure 6). In the case of the ytterbium complex, aq uadratic variation is found for both the residual ICT and the ytterbium-based emissions (Figure 4a), clearly indicating that the NIR luminescence originates from at wo-photon antenna effect (TPAo ft he ligand followed by energy transfer to the emissive states).…”

Helicenic Complexes of Lanthanides: Influence of the f‐Element on the Intersystem Crossing Efficiency and Competition between Luminescence and Oxygen Sensitization

“…As mentioned before, all three complexes are characterized by a broad, structureless emission centered on the helicene bipyridine ligand around 550–580 nm slightly sensitive to the nature of the lanthanide cation (with Eu > Gd ≈ Yb). [16a] In contrast with what had been shown for ligand L , no phosphorescence signal could be observed at 77K for the all complexes in solution presumably because of the overwhelming presence of the ILCT band. Interestingly, the intensity of emission band slightly increases upon degassing the solution (Figure ) suggesting that both fluorescence (ILCT) and phosphorescence (from the triplet state) overlap in this broad transition.…”

“…Although such a dissociation is not observed at mM concentration, as witnessed by the presence of a single complex species in the NMR spectrum of 1 (Figure S10), it might be taking place in the high dilution concentration (10 –6 m ) typically used in our spectroscopy experiments . To tackle this drawback, all the photophysical study has been conducted in dichloromethane solution in the presence of an excess of Ln(hfac) 3 · 2H 2 O in order to displace the equilibrium (1) towards the quantitative formation of L Ln(hfac) 3 (Figure ).…”