Tuning the Decay Time of Lanthanide‐Based Near Infrared Luminescence from Micro‐ to Milliseconds through d→f Energy Transfer in Discrete Heterobimetallic Complexes

Torelli, Stéphane; Imbert, Daniel; Cantuel, Martine; Bérnardinelli, Gerald; Delahaye, Sandra; Hauser, Andreas; Bünzli, Jean‐Claude G.; Piguet, Claude

doi:10.1002/chem.200401158

“…Subsequent partial L1!Cr III and L1!Er III energy transfer processes followed by internal relaxation processes (see Figure 3 a) result in rich mixed ligand-centered and metal-centered luminescence, as previously described for several Cr III /Ln III pairs in molecular complexes (Figure 4). [10,12,14] From the excitation spectrum of CrErCr recorded upon monitoring the Cr( 2 E! 4 A 2 ) emission band at 13 380 cm À1 (in the red region; Figure S6a), we can easily locate the lowenergy spin-allowed Cr( 4 T 2 !…”

Section: +mentioning

confidence: 99%

“…Based on previous studies, [10,11] Figure 2) appears to be a good candidate, as the two Cr III sensitizers are in strong ligand-field environments and therefore can push both the Cr( 4 T 2 ) excited states and the associated broad absorption bands to sufficiently high energy ( Figure S1 in the Supporting Information), while the comparatively large nephelauxetic effect lowers the energy of the 2 E state of the Cr III center to around 13 400 cm À1 . These conditions are required for the fine-tuning of the target intermetallic Cr( 2 E)!Er( 4 I 9/2 ) energy transfer ( Figure 3).…”

mentioning

confidence: 91%

“…[11] With these points in mind, we reacted the segmental ligand L1 with stoichiometric amounts of Ln(CF 3 Table S1) suitable for X-ray diffraction studies could be isolated by slow diffusion of diethyl ether into concentrated solutions of the complex in propionitrile. [13] All the CrÀN and LnÀN bond lengths are typical (Tables S2 and S3), [10] and the global pseudo-D 3 symmetrical triple-helical ion [CrLnCr(L1) 3 ] 9+ is made up of a pseudo-tricapped trigonal {LnN 9 } prism sandwiched between two pseudo-octahedral {CrN 6 } moieties ( Figure 2 and Figure S2). Two slightly different cations with opposite helicities exist in the asymmetric unit, but the geometrical differences, except for the chirality, are marginal ( Figure S3), and we conclude that the three metals in [CrLnCr(L1) 3 ] 9+ are 1) aligned along a pseudo-threefold axis, 2) protected from the solvent by the wrapping of the three helical ligand strands (Table S4), and 3) regularly spaced with Cr···Eu = 8.8(1) and Cr···Yb = 8.9(1) .…”

mentioning

confidence: 99%

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Near‐Infrared→Visible Light Upconversion in a Molecular Trinuclear d–f–d Complex

Aboshyan-Sorgho

¹

,

Besnard

²

,

Pattison

³

et al. 2011

Self Cite

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Molecular nonlinear-optical (NLO) phenomena are currently being exploited for the design of visible emitting bioprobes with unprecedented properties that result from 1) the transparency of living tissues toward low-energy near-infrared (NIR) incident radiation and 2) the improved focusing of the light from an excitation laser beam within nanometric volumes.[1] Nonresonant multiphoton absorption produces a single emission during the irradiation; this emission corresponds to a multiple of the energy of the incident beam, as, for example, in second-harmonic generation (Figure 1 a), while resonant multiphoton absorption populates a real excited state of the chromophore, which relaxes and fluoresces with the same characteristics as if sensitized by a linear excitation process (Figure 1 b).[2] Beyond the optimization of polarizable push-pull p-aromatic molecules for NLO optical response, [2] and the related development of upconverted fluorescence signals in polyaromatic platforms produced by metal-sensitized triplet-triplet annihilation photochemistry, [3] Le Bozec, Maury, Andraud, and their respective co-workers demonstrated that trivalent lanthanide ions (Ln III ) may efficiently contribute to the polarization of coordinated aromatic ligands for resonant multiphoton absorption.[4] Moreover, the wealth of accessible long-lived metal-centered luminescent emissive levels can be exploited for two-photon-excited time-gated fluorescence analyses of biological tissues. [5] Interestingly, the existence of several real excited states located between the ground state and the target excited state of lanthanide acceptors opens novel perspectives for the operation of alternative sensitizing mechanisms that take advantage of these electronic relays for successive linear excitations by one (Figure 1 c) or several (Figure 1 d) moieties, thus leading to an excited-state absorption (ESA) process or sequential energy transfer upconversion (ETU), both of which are followed by luminescence.[6] Although they operate by different principles, that is, they involve real rather than virtual intermediate excited levels during the multiphoton absorption processes, two-photon upconversion fluorescence processes (Figure 1 c, d) can be considered as nonlinear because of the quadratic dependence of the efficiency (I) on the incident intensity of the excitation light (I / P 2 ). [4,6] Upconversion has been regularly reported for trivalent lanthanide cations doped into low-phonon inorganic matrices, [6] particularly for applications in bioanalyses, telecommunications, and solar energy conversion, [7] but it is still unknown in molecular erbium complexes [8] because of the high effective vibrational energy " hw eff % 2000 cm À1 that is typical of the molecular vibrations of organic ligands or of closely interacting solvent molecules, which result in efficient nonradiative relaxation of 4f-4f transitions.[9] In their seminal contribution dedicated to the search for upconversion fluorescence in the molecular complexes Na 3 [Ln(pyridine-2,6-dicarboxylat...

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“…Based on previous studies, [10,11] Figure 2) appears to be a good candidate, as the two Cr III sensitizers are in strong ligand-field environments and therefore can push both the Cr( 4 T 2 ) excited states and the associated broad absorption bands to sufficiently high energy ( Figure S1 in the Supporting Information), while the comparatively large nephelauxetic effect lowers the energy of the 2 E state of the Cr III center to around 13 400 cm À1 . These conditions are required for the fine-tuning of the target intermetallic Cr( 2 E)!Er( 4 I 9/2 ) energy transfer ( Figure 3).…”

mentioning

confidence: 94%

“…[11] With these points in mind, we reacted the segmental ligand L1 with stoichiometric amounts of Ln(CF 3 Table S1) suitable for X-ray diffraction studies could be isolated by slow diffusion of diethyl ether into concentrated solutions of the complex in propionitrile. [13] All the CrÀN and LnÀN bond lengths are typical (Tables S2 and S3), [10] and the global pseudo-D 3 symmetrical triple-helical ion [CrLnCr(L1) 3 ] 9+ is made up of a pseudo-tricapped trigonal {LnN 9 } prism sandwiched between two pseudo-octahedral {CrN 6 } moieties ( Figure 2 and Figure S2). Two slightly different cations with opposite helicities exist in the asymmetric unit, but the geometrical differences, except for the chirality, are marginal 3 ] 9+ are 1) aligned along a pseudo-threefold axis, 2) protected from the solvent by the wrapping of the three helical ligand strands (Table S4), and 3) regularly spaced with Cr···Eu = 8.8(1) and Cr···Yb = 8.9(1) .…”

mentioning

confidence: 99%

Near‐Infrared→Visible Light Upconversion in a Molecular Trinuclear d–f–d Complex

Aboshyan-Sorgho¹,

Besnard²,

Pattison³

et al. 2011

Self Cite

View full text Add to dashboard Cite

Molecular nonlinear-optical (NLO) phenomena are currently being exploited for the design of visible emitting bioprobes with unprecedented properties that result from 1) the transparency of living tissues toward low-energy near-infrared (NIR) incident radiation and 2) the improved focusing of the light from an excitation laser beam within nanometric volumes.[1] Nonresonant multiphoton absorption produces a single emission during the irradiation; this emission corresponds to a multiple of the energy of the incident beam, as, for example, in second-harmonic generation (Figure 1 a), while resonant multiphoton absorption populates a real excited state of the chromophore, which relaxes and fluoresces with the same characteristics as if sensitized by a linear excitation process (Figure 1 b).[2] Beyond the optimization of polarizable push-pull p-aromatic molecules for NLO optical response, [2] and the related development of upconverted fluorescence signals in polyaromatic platforms produced by metal-sensitized triplet-triplet annihilation photochemistry, [3] Le Bozec, Maury, Andraud, and their respective co-workers demonstrated that trivalent lanthanide ions (Ln III ) may efficiently contribute to the polarization of coordinated aromatic ligands for resonant multiphoton absorption.[4] Moreover, the wealth of accessible long-lived metal-centered luminescent emissive levels can be exploited for two-photon-excited time-gated fluorescence analyses of biological tissues. [5] Interestingly, the existence of several real excited states located between the ground state and the target excited state of lanthanide acceptors opens novel perspectives for the operation of alternative sensitizing mechanisms that take advantage of these electronic relays for successive linear excitations by one (Figure 1 c) or several (Figure 1 d) moieties, thus leading to an excited-state absorption (ESA) process or sequential energy transfer upconversion (ETU), both of which are followed by luminescence.[6] Although they operate by different principles, that is, they involve real rather than virtual intermediate excited levels during the multiphoton absorption processes, two-photon upconversion fluorescence processes (Figure 1 c, d) can be considered as nonlinear because of the quadratic dependence of the efficiency (I) on the incident intensity of the excitation light (I / P 2 ). [4,6] Upconversion has been regularly reported for trivalent lanthanide cations doped into low-phonon inorganic matrices, [6] particularly for applications in bioanalyses, telecommunications, and solar energy conversion, [7] but it is still unknown in molecular erbium complexes [8] because of the high effective vibrational energy " hw eff % 2000 cm À1 that is typical of the molecular vibrations of organic ligands or of closely interacting solvent molecules, which result in efficient nonradiative relaxation of 4f-4f transitions.[9] In their seminal contribution dedicated to the search for upconversion fluorescence in the molecular complexes Na 3 [Ln(pyridine-2,6-dicarboxylate...

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Electroluminescence Based on Lanthanide Complexes

Bian¹,

Huang²

2010

Rare Earth Coordination Chemistry

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Tuning the Decay Time of Lanthanide‐Based Near Infrared Luminescence from Micro‐ to Milliseconds through d→f Energy Transfer in Discrete Heterobimetallic Complexes

Cited by 187 publications

References 61 publications

Near‐Infrared→Visible Light Upconversion in a Molecular Trinuclear d–f–d Complex

Near‐Infrared→Visible Light Upconversion in a Molecular Trinuclear d–f–d Complex

Near‐Infrared→Visible Light Upconversion in a Molecular Trinuclear d–f–d Complex

Electroluminescence Based on Lanthanide Complexes

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