Using the Antenna Effect as a Spectroscopic Tool: Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [Eu<sup>III</sup>(3,4,3-LI(1,2-HOPO))]<sup>−</sup>

Abergel, Rebecca J.; D’Aléo, Anthony; Leung, Clara Ng Pak; Shuh, David K.; Raymond, Kenneth N.

doi:10.1021/ic9013703

Cited by 63 publications

(116 citation statements)

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“…This observation is consistent with previous reports describing Eu(III) sensitization by 343 phosphorescence in the Eu-343 molecular complex. 25 The absence of europium luminescence in no-343 and undoped NaGdF 4 -3,4,3 controls upon UV excitation corroborate the interpretation that the red emission from these particles is dependent on ligand-to-metal energy transfer between 343 surface chelators and the Eu(III) lattice dopants. Probes of nanocrystal luminescence upon 464 nm europium excitation ( The conditions used for achieving nanoparticle ligation allowed for the likelihood of particle surface etching, with aqueous Eu 3+ and Gd…”

mentioning

confidence: 54%

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Agbo

Sturzbecher-Hoehne

et al. 2016

ACS Photonics

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The small absorption cross-sections (ε < 10 M ) in sensitizing excited states in lanthanide nanocrystals. Here, we detail the photophysics of NaGd 1-x Eu x F 4 nanoparticles featuring surface display of the ligand 3,4,3-LI(1,2-HOPO), an aromatic antenna functioning as the terminal light absorber in this system. The result is a ligand-nanocrystal hybrid which converts UV (250-360 nm) light into red Eu(III) luminescence with an external quantum yield of 3.3%. We analyze this sensitization process, responsible for a 10 4 fold increase in luminescence relative to metal-centered excitation, through a quantitative treatment of energy transfer between ligand and metal states. 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 The problem of spectral mismatch between semiconductor band gaps and Earth's terrestrial solar spectrum remains an issue plaguing the efficiency of modern photovoltaics 1,2 . A number of methods have been proposed and implemented to address this problem, including the incorporation of materials absorbing at different wavelengths in multi-junction photovoltaics, modification of the intrinsic Si band gap through advanced nanofabrication methods, and the respective up-and down-conversion of lowand high-frequency EM radiation into photons suited for bulk Si absorption 3-6 .Currently, research in the field of spectral conversion is dominated by lanthanide photophysics, where exploitation of f-element nanocrystals has resulted in a wide array of potential downconverters 7-12 . However, the maturation of these prototype systems into practical applications has largely been hampered by the low molar absorptivities of f-f transitions (< 10 M -1 cm -1 ) 13,14 . Routes previously explored to address this challenge include the relaxation of Laporte selection rules through the embedding of lanthanide ions in low-symmetry crystal hosts and the employ of parityallowed, d → f charge transfer in divalent lanthanides such as Eu(II) 15 . By contrast, the possibility of photosensitizing nanocrystalline lanthanides with organic ligands remains a relatively novel method of enhancing f-block nanoparticle light absorption, though a recent study has implemented such schemes in light upconversion 16 , and some work exploring the photochemical effects surface ligands have on lanthanide nanoparticle luminescence has been conducted 17-23 .In this report, we describe the construction of Eu-doped, rare-earth nanoparticles featuring a hydroxypyridinone (HOPO) ligand derivative, 3,4,3-LI(1,2-HOPO) (abbreviated '343'), as an ultraviolet photosensitizer. These constructs depart significantly from known systems such as dyesensitized TiO 2 nanoparticles, where the stated purpose of photon absorption is generation of delocalized charge carriers, rather than the efficient production and radiative decay of lower-frequency excitons, the central focus of this work.It has been previously shown that population of Eu(III) ex...

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confidence: 54%

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Agbo

Sturzbecher-Hoehne

et al. 2016

ACS Photonics

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“…Emission spectra were recorded on a HORIBA Jobin Yvon IBH FluoroLog-3 spectrofluorimeter, used in steady state mode and luminescence lifetimes were determined with time-correlated single photon counting and multichannel scaling measurements (details provided in SI Appendix). Quantum yields and kinetic parameters were determined as previously described (26,39). The brightness was calculated as the product of the molar absorption coefficient and the luminescence quantum yield.…”

Section: Methodsmentioning

confidence: 99%

Siderocalin-mediated recognition, sensitization, and cellular uptake of actinides

Allred

Rupert

Gauny

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Synthetic radionuclides, such as the transuranic actinides plutonium, americium, and curium, present severe health threats as contaminants, and understanding the scope of the biochemical interactions involved in actinide transport is instrumental in managing human contamination. Here we show that siderocalin, a mammalian siderophore-binding protein from the lipocalin family, specifically binds lanthanide and actinide complexes through molecular recognition of the ligands chelating the metal ions. Using crystallography, we structurally characterized the resulting siderocalin-transuranic actinide complexes, providing unprecedented insights into the biological coordination of heavy radioelements. In controlled in vitro assays, we found that intracellular plutonium uptake can occur through siderocalin-mediated endocytosis. We also demonstrated that siderocalin can act as a synergistic antenna to sensitize the luminescence of trivalent lanthanide and actinide ions in ternary protein-ligand complexes, dramatically increasing the brightness and efficiency of intramolecular energy transfer processes that give rise to metal luminescence. Our results identify siderocalin as a potential player in the biological trafficking of f elements, but through a secondary ligandbased metal sequestration mechanism. Beyond elucidating contamination pathways, this work is a starting point for the design of twostage biomimetic platforms for photoluminescence, separation, and transport applications.actinide transport | siderocalin | protein crystallography | luminescence spectroscopy | antenna effect E vents of the last decade have heightened public concern that radionuclides may be released to the environment either deliberately or accidentally (1, 2), with such events potentially leading to the internal contamination of a large number of individuals. The actinides are all highly radioactive, as are some lanthanide fission products, and many of their isotopes decay by alpha particle emission (3). Once internalized, they are distributed to various tissues with patterns that depend on the chemical and physical form of the contaminant in question (4). The densely ionizing alpha particles emitted by actinides when retained can cause tissue damage and induce cancer in target tissues in a dosedependent manner (5). Sufficiently high radionuclide doses may also cause manifestations of acute radiation syndrome. The tissue distribution of an actinide will therefore determine the pattern of injury observed and its radiological and chemical toxicities may lead to serious adverse health effects (6-8). Although they are known to rapidly circulate and deposit into major organs such as bone, liver, or kidney after contamination (6,(8)(9)(10), the specific molecular mechanisms associated with mammalian uptake of these toxic heavy elements remain largely unexplored. Proposed mammalian actinide acquisition and transport mechanisms have typically focused on proteins that use conserved motifs to directly bind the essential elements iron or calcium (6, 8, 10-...

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“…As a stronger competing ligand was needed, series of experiments were conducted using 3,4,3-LI(1,2-HOPO); a synthetic chelator whose solution thermodynamics with Eu(III), Tb(III), and Cm(III) were previously characterized and reported in the literature. [68][69][70] Upon addition of a 2-fold excess of 3,4,3-LI(1,2-HOPO), treatment at 60°C for four days, and 25°C for three days, the three DO3A-coumarin complexes could finally be challenged. In divided into separate aliquots and the competing 3,4,3-LI(1,2-HOPO) ligand were added to reach concentrations varying from 0 to 15 μM.…”

Section: Complex Stabilitymentioning

confidence: 99%

Investigating subtle 4f vs. 5f coordination differences using kinetically inert Eu(iii), Tb(iii), and Cm(iii) complexes of a coumarin-appended 1,4,7,10-tetraazacyclododecane-1,4,7-triacetate (DO3A) ligand

et al. 2018

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TitleInvestigating subtle 4f vs. 5f coordination differences using kinetically inert Eu(iii), Tb(iii), and Cm(iii) complexes of a coumarin-appended 1,4,7,10-tetraazacyclododecane-1,4,7-triacetate (DO3A) ligand In order to reveal subtle differences between the solution chemistries of trivalent 4f and 5f elements, the physicochemical and photophysical properties of europium(III), terbium(III) and curium(III) complexes formed with a 7-methoxy-coumarin appended 1,4,7,10-tetraazadodecane-1,4,7-triacid (DO3A) ligand were studied. All three complexes were found to be kinetically inert and exhibit stability constants similar to their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) equivalents. The Cm(III) and Eu(III) complexes feature strong sensitised emission, while the triplet energy of the coumarin prohibits efficient sensitisation of the Tb(III) analogue. The data presented here indicate significant differences in perturbation of the sensitising chromophore photophysics between the 4f and 5f elements. In contrast, the size of the metal center appears to not be a determining factor for the physicochemical properties of these kinetically inert Eu(III), Tb(III,) and Cm(III) complexes.

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Using the Antenna Effect as a Spectroscopic Tool: Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [Eu^III(3,4,3-LI(1,2-HOPO))]⁻

Cited by 63 publications

References 12 publications

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Siderocalin-mediated recognition, sensitization, and cellular uptake of actinides

Investigating subtle 4f vs. 5f coordination differences using kinetically inert Eu(iii), Tb(iii), and Cm(iii) complexes of a coumarin-appended 1,4,7,10-tetraazacyclododecane-1,4,7-triacetate (DO3A) ligand

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Using the Antenna Effect as a Spectroscopic Tool: Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [EuIII(3,4,3-LI(1,2-HOPO))]−

Cited by 63 publications

References 12 publications

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Enhanced Ultraviolet Photon Capture in Ligand-Sensitized Nanocrystals

Siderocalin-mediated recognition, sensitization, and cellular uptake of actinides

Investigating subtle 4f vs. 5f coordination differences using kinetically inert Eu(iii), Tb(iii), and Cm(iii) complexes of a coumarin-appended 1,4,7,10-tetraazacyclododecane-1,4,7-triacetate (DO3A) ligand

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Using the Antenna Effect as a Spectroscopic Tool: Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [Eu^III(3,4,3-LI(1,2-HOPO))]⁻