1
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Simms CH, Nielsen VRM, Sørensen TJ, Faulkner S, Langton MJ. Photoswitchable luminescent lanthanide complexes controlled and interrogated by four orthogonal wavelengths of light. Phys Chem Chem Phys 2024; 26:18683-18691. [PMID: 38922672 DOI: 10.1039/d4cp02243b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
Optical information storage requires careful control of excitation and emission wavelengths in a reversible and orthogonal manner to enable efficient reading, writing, and erasing of information. Photochromic systems, in which a photoswitch is typcially coupled to an emissive organic fluorophore, have much promise in this regard. However, these suffer from considerable spectral overlap between the switch and fluorophore, such that their emissive and photoswitchable properties are not orthogonal. Here, we overcome this limitation by coupling visible/NIR emissive lanthanide complexes with molecular photoswitches, enabling reversible and orthogonal photoswitching with visible light. Crucially, photoswitching does not lead to sensitised emission from the lanthanide, while excitation of the lanthanide does not induce photoswitching, enabling the state of the system to be probed without perturbation of the switch. This opens up the possibility of developing multi-colour read-write methods for information storage using emissive photoswitches.
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Affiliation(s)
- Charlie H Simms
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Mansfield road, Oxford, OX1 3TA, UK.
| | - Villads R M Nielsen
- Nano-Science Centre and Department of Chemistry University of Copenhagen Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Nano-Science Centre and Department of Chemistry University of Copenhagen Universitetsparken 5, 2100 København Ø, Denmark
| | - Stephen Faulkner
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Mansfield road, Oxford, OX1 3TA, UK.
| | - Matthew J Langton
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Mansfield road, Oxford, OX1 3TA, UK.
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2
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Mortensen SS, Nielsen VRM, Sørensen TJ. Contrasting impact of coordination polyhedra and site symmetry on the electronic energy levels in nine-coordinated Eu(III) and Sm(III) crystals structures determined from single crystal luminescence spectra. Dalton Trans 2024; 53:10079-10092. [PMID: 38712555 DOI: 10.1039/d4dt00157e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Lanthanide luminescence is characterised by "forbidden" 4f-4f transitions and a complicated electronic structure. Our understanding of trivalent lanthanide(III) ion luminescence is centered on Eu3+ because absorbing and emitting transitions in Eu3+ occur from a single electronic energy level. In Sm3+ both absorbing and emitting multiplets have a larger multiplicity. A band arising in transitions from the first emitting state multiplet to the ground state multiplet will have nine lines for a Sm3+ complex. In this study, high-resolution emission and excitation spectra were used to determine the electronic energy levels for the lowest multiplet and first emitting multiplet in four Sm3+ compounds with either tricapped trigonal prismatic TTP or capped square antiprismatic cSAP coordination polyhedra but different site symmetry. This was achieved by the use of Boltzmann distribution population analysis and experimentally determined transition probabilities from emission and excitation spectra. Using this analysis it was possible to show the effect of changing three oxygen atoms with three nitrogen atoms in the donor set for two compounds with the same coordination polyhedra and site symmetry. This work celebrates the 40th anniversary of Kirby and Richardson's first report of [Eu(ODA)3]3- luminescence.
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Affiliation(s)
- Sabina Svava Mortensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Villads R M Nielsen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
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3
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Kofod N, Sørensen TJ. Step-wise changes in the excited state lifetime of [Eu(D 2O) 9] 3+ and [Eu(DOTA)(D 2O)] - as a function of the number of inner-sphere O-H oscillators. Dalton Trans 2024; 53:9741-9749. [PMID: 38780119 DOI: 10.1039/d4dt00744a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Lanthanide luminescence is dominated by quenching by high-energy oscillators in the chemical environment. The rate of non-radiative energy transfer to a single H2O molecule coordinated to a Eu3+ ion exceeds the usual rates of emission by an order of magnitude. We know these rates, but the details of these energy transfer processes are yet to be established. In this work, we study the quenching rates of [Eu(D2O)9]3+ and [Eu(DOTA)(D2O)]- in H2O/D2O mixtures by sequentially exchanging the deuterons with protons. Flash freezing the solutions allows us to identify species with various D/H contents in solution and thus to quantify the energy transfer processes to individual OH-oscillators. This is not possible in solution due to fast exchange in the ensembles present at room temperature. We conclude that the energy transfer processes are accurately described, predicted, and simulated using a step-wise addition of the rates of quenching by each O-H oscillator. This documents the sequential increase in the rate of the energy transfer processes in the quenching of lanthanide luminescence, and further provides a methodology to identify isotopic impurities in deuterated lanthanide systems in solution.
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Affiliation(s)
- Nicolaj Kofod
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M9 13PL, UK.
- Department of Chemistry and Nano-Science Centre, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Thomas Just Sørensen
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M9 13PL, UK.
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4
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Nielsen LG, Andersen HOB, Kenwright AM, Platas-Iglesias C, So Rensen TJ. Using Chiral Auxiliaries to Mimic the Effect of Chiral Media on the Structure of Lanthanide(III) Complexes Common in Bioimaging and Diagnostic MRI. Inorg Chem 2024; 63:7560-7570. [PMID: 38610098 DOI: 10.1021/acs.inorgchem.3c01589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2024]
Abstract
[Ln·DOTA]- complexes and systems derived therefrom are commonly used in MRI and optical bioimaging. These lanthanide(III) complexes are chiral, and, in solution, they are present in four forms, with two sets of enantiomers, with the ligand donors arranged in either a square antiprismatic, SAP, or twisted square antiprismatic geometry, TSAP. This complicated speciation is found in laboratory samples. To investigate speciation in biological media, when Ln·DOTA-like complexes interact with chiral biomolecules, six Eu·DOTA-monoamide complexes were prepared and investigated by using 1D and 2D 1H NMR. To emulate the chirality of biological media, the amide pendant arm was modified with one or two chiral centers. It is known that a chiral center on the DOTA scaffold significantly influences the properties of the system. Here, it was found that chirality much further away from the metal center changes the available conformational space and that both chiral centers and amide cis/trans isomerism may need to be considered─a fact that, for the optically enriched materials, led to the conclusion that eight chemically different forms may need to be considered, instead of the four forms necessary for DOTA. The results reported here clearly demonstrate the diverse speciation that must be considered when correlating an observation to a structure of a lanthanide(III) complex.
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Affiliation(s)
- Lea Gundorff Nielsen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, Ko̷benhavn Ø DK2100, Denmark
| | - Helene O B Andersen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, Ko̷benhavn Ø DK2100, Denmark
| | - Alan M Kenwright
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Carlos Platas-Iglesias
- Centro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, A Coruña, Galicia 15071, Spain
| | - Thomas Just So Rensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, Ko̷benhavn Ø DK2100, Denmark
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5
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Kofod N, Henrichsen MJ, Sørensen TJ. Mapping the distribution of electronic states within the 5D 4 and 7F 6 levels of Tb 3+ complexes with optical spectroscopy. Dalton Trans 2024; 53:4461-4470. [PMID: 38372338 DOI: 10.1039/d3dt03657j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The Tb(III) ion has the most intense luminescence of the trivalent lanthanide(III) ions. In contrast to Eu(III), where the two levels only include a single state, the high number of electronic states in the ground (7F6) and emitting (5D4) levels makes detailed interpretations of the electronic structure-the crystal field-difficult. Here, luminescence emission and excitation spectra of Tb(III) complexes with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA, [Tb(DOTA)(H2O)]-), ethylenediaminetetraacetic acid (EDTA, [Tb(EDTA)(H2O)3]-) and diethylenetriaminepentaacetic acid (DTPA, [Tb(DTPA)(H2O)]2-) as well as the Tb(III) aqua ion ([Tb(H2O)9]3+) were recorded at room temperature and in frozen solution. Using these data the electronic structure of the 5D4 multiplets of Tb(III) was mapped by considering the transitions to the singly degenerate 7F0 state. A detailed spectroscopic investigation was performed and it was found that the 5D4 multiplet could accurately be described as a single band for [Tb(H2O)9]3+, [Tb(DOTA)(H2O)]- and [Tb(EDTA)(H2O)3]-. In contrast, for [Tb(DTPA)(H2O)]2- two bands were needed. These results demonstrated the ability of describing the electronic structure of the emitting 5D4 multiplet using emission spectra. This offers an avenue for investigating the relationship between molecular structure and luminescent properties in detailed photophysical studies of Tb(III) ion complexes.
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Affiliation(s)
- Nicolaj Kofod
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Margrete Juel Henrichsen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
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6
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Nielsen VRM, Nawrocki PR, Sørensen TJ. Electronic Structure of Neodymium(III) and Europium(III) Resolved in Solution Using High-Resolution Optical Spectroscopy and Population Analysis. J Phys Chem A 2023; 127:3577-3590. [PMID: 37053513 DOI: 10.1021/acs.jpca.3c00233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Solution chemistry of the lanthanide(III) ions is unexplored and relevant: extraction and recycling processes exclusively operate in solution, MRI is a solution-phase method, and bioassays are done in solution. However, the molecular structure of the lanthanide(III) ions in solution is poorly described, especially for the near-IR (NIR)-emitting lanthanides, as these are difficult to investigate using optical tools, which has limited the availability of experimental data. Here we report a custom-built spectrometer dedicated to investigation of lanthanide(III) luminescence in the NIR region. Absorption, luminescence excitation, and luminescence spectra of five complexes of europium(III) and neodymium(III) were acquired. The obtained spectra display high spectral resolution and high signal-to-noise ratios. Using the high-quality data, a method for determining the electronic structure for the thermal ground states and emitting states is proposed. It combines Boltzmann distributions with population analysis and uses the experimentally determined relative transition probabilities from both excitation and emission data. The method was tested on the five europium(III) complexes and was used to resolve the electronic structures of the ground state and the emitting state of neodymium(III) in five different solution complexes. This is the first step toward correlating optical spectra with chemical structure in solution for NIR-emitting lanthanide complexes.
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Affiliation(s)
- Villads R M Nielsen
- Department of Chemistry and Nano-Science Centre, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Patrick R Nawrocki
- Department of Chemistry and Nano-Science Centre, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Thomas Just Sørensen
- Department of Chemistry and Nano-Science Centre, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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7
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Nielsen LG, Sørensen TJ. Effect of buffers and pH in antenna sensitized Eu(III) luminescence. Methods Appl Fluoresc 2023; 11. [PMID: 36696692 DOI: 10.1088/2050-6120/acb63a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/25/2023] [Indexed: 01/26/2023]
Abstract
The photophysics of a europium(III) complex of 1,4,7,10-tetraazacycododecane-1,4,7-triacetic acid-10-(2-methylene)-1-azathioxanthone was investigated in three buffer systems and at three pH values. The buffers-phosphate buffered saline (PBS), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), and universal buffer (UB)-had no effect on the europium luminescence, but a lower overall emission intensity was determined in HEPES. It was found that this was due to quenching of the 1-azathioxanthone first excited singlet state by HEPES. The effect of pH on the photophysics of the complex was found to be minimal, and protonation of the pyridine nitrogen was found to be irrelevant. Even so, pH was shown to change the intensity ratio between 1-azathioxanthone fluorescence and europium luminescence. It was concluded that the full photophysics of a potential molecular probe should be investigated to achieve the best possible results in any application.
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Affiliation(s)
- Lea Gundorff Nielsen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, København Ø, Denmark
| | - Thomas Just Sørensen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, København Ø, Denmark
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8
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Kofod N, Sørensen TJ. Tb 3+ Photophysics: Mapping Excited State Dynamics of [Tb(H 2O) 9] 3+ Using Molecular Photophysics. J Phys Chem Lett 2022; 13:11968-11973. [PMID: 36534789 DOI: 10.1021/acs.jpclett.2c03506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The study of optical transitions in lanthanide(III) ions has evolved separately from molecular photophysics, but the framework still applies to these forbidden transitions. In this study, a detailed photophysical characterization of the [Tb(H2O)9]3+ aqua ion was performed. The luminescence quantum yield (Φlum), excited state lifetime (τobs), radiative (kr ≡ A) and nonradiative (knr) rate constants, and oscillator strength (f) were determined for Tb(CF3SO3)3 in H2O/D2O mixtures in order to map the radiative and nonradiative transition probabilities. It was shown that the intense luminescence observed from Tb3+ compared to other Ln3+ ions is not due to a higher transition probability of emission but rather due to a lack of quenching, quantified by quenching to O-H oscillators in the aqua ion of kq(OH) = 2090 s-1 for terbium and kq(OH) = 8840 s-1 for europium. In addition, the Horrocks method of determining inner-sphere solvent molecules has been revisited, and it was concluded that the Tb3+ is 9-coordinated in aqueous solution.
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Affiliation(s)
- Nicolaj Kofod
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK2100København Ø, Denmark
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK2100København Ø, Denmark
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9
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Mortensen SS, Marciniak Nielsen MA, Nawrocki P, Sørensen TJ. Electronic Energy Levels and Optical Transitions in Samarium(III) Solvates. J Phys Chem A 2022; 126:8596-8605. [DOI: 10.1021/acs.jpca.2c04793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Sabina Svava Mortensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Malthe Asmus Marciniak Nielsen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Patrick Nawrocki
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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10
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Storm Thomsen M, Andersen HOB, Sørensen TJ. Long story short: donor set symmetry in [Eu(DOTA)(H 2O)] - crystals determines the electronic structure. Dalton Trans 2022; 51:14118-14124. [PMID: 36043508 DOI: 10.1039/d2dt02172b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid DOTA have been studied in great detail due to their use as MRI contrast agents. Since the first report from Desreux in 1980, the Ln[DOTA]- complexes of gadolinium(III) in particular have been thoroughly investigated. The forms of the nine-coordinated [Ln(DOTA)(H2O)]- complexes are well known, and the ligand backbone has been used extensively to create functional MRI contrast agents, luminescent probes, and as a model system for studying the properties of lanthanide(III) ions. In solution, the photophysical properties have been mapped, but as the structures are not known, direct structure-property relationships have not been created. Here, the electronic properties of two Eu[DOTA] compounds (1 and 2) and a Eu[DOTA]-like compound (3) were studied using single-crystal luminescence spectroscopy. The donor set in the three compounds is identical (4N 4O 1O), and using the symmetry deviation value σideal it was shown that the coordination geometry is close to identical. Nevertheless, the electronic properties evaluated using the luminescence spectrum were found to differ significantly between the three compounds. The magnitude of the crystal field splitting was found not to scale with the symmetry of the coordination geometry. It was concluded that the donor set dictates the splitting, yet the structure-property relationships governing the electronic properties of europium(III) ions still elude us.
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Affiliation(s)
- Maria Storm Thomsen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark.
| | - Helene Obel Bøch Andersen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark.
| | - Thomas Just Sørensen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark.
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11
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Nawrocki PR, Nielsen VMR, Sørensen TJ. A high-sensitivity rapid acquisition spectrometer for lanthanide(III) luminescence. Methods Appl Fluoresc 2022; 10. [PMID: 36027890 DOI: 10.1088/2050-6120/ac8d4d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/26/2022] [Indexed: 11/11/2022]
Abstract
Detecting luminescence beyond 750-800 nm becomes problematic as most conventional detectors are less sensitive in this range, and as simple corrections stops being accurate. Lanthanide luminescence occurs in narrow bands across the spectrum from 350-2000 nm. The most emissive lanthanide(III) ions have bands from 450 nm to 850 nm, some with additional bands in the NIR. Investigating the NIR bands are hard, but the difficulties start already at 700 nm. In general, the photon flux from lanthanide(III) emitters is not great, and the bands beyond 700 nm are very weak, we therefore decided to build a spectrometer based on cameras for microscopy with single-photon detection capabilities. This was found to allieviate all limitations and to allow for fast and efficient recording of luminescence spectra in the range from 450 to 950 nm. The spectrometer characteristics were investigated and the performance was benchmarked against two commercial spectrometers. We conclude that this spectrometer is ideal for investigating lanthanide luminescence, an all other emitters with emission in the target range.
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Affiliation(s)
- Patrick R Nawrocki
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, København Ø, 2100, DENMARK
| | - Villads M R Nielsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, København Ø, 2100, DENMARK
| | - Thomas Just Sørensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, København Ø, 2100, DENMARK
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12
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Thomsen MS, Nawrocki PR, Kofod N, Sørensen TJ. Seven Europium(III) Complexes in Solution – the Importance of Reporting Data When Investigating Luminescence Spectra and Electronic Structure. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Maria S. Thomsen
- Department of Chemistry and Nano-Science Center University of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Patrick R. Nawrocki
- Department of Chemistry and Nano-Science Center University of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Nicolaj Kofod
- Department of Chemistry and Nano-Science Center University of Copenhagen Universitetsparken 5 2100 København Ø Denmark
| | - Thomas J. Sørensen
- Department of Chemistry and Nano-Science Center University of Copenhagen Universitetsparken 5 2100 København Ø Denmark
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13
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Danaf NA, Kretzschmar J, Jahn B, Singer H, Pol A, Op den Camp HJM, Steudtner R, Lamb DC, Drobot B, Daumann LJ. Studies of pyrroloquinoline quinone species in solution and in lanthanide-dependent methanol dehydrogenases. Phys Chem Chem Phys 2022; 24:15397-15405. [PMID: 35704886 DOI: 10.1039/d2cp00311b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pyrroloquinoline quinone (PQQ) is a redox cofactor in calcium- and lanthanide-dependent alcohol dehydrogenases that has been known and studied for over 40 years. Despite its long history, many questions regarding its fluorescence properties, speciation in solution and in the active site of alcohol dehydrogenase remain open. Here we investigate the effects of pH and temperature on the distribution of different PQQ species (H3PQQ to PQQ3- in addition to water adducts and in complex with lanthanides) with NMR and UV-Vis spectroscopy as well as time-resolved laser-induced fluorescence spectroscopy (TRLFS). Using a europium derivative from a new, recently-discovered class of lanthanide-dependent methanol dehydrogenase (MDH) enzymes, we utilized two techniques to monitor Ln binding to the active sites of these enzymes. Employing TRLFS, we were able to follow Eu(III) binding directly to the active site of MDH using its luminescence and could quantify three Eu(III) states: Eu(III) in the active site of MDH, but also in solution as PQQ-bound Eu(III) and in the aquo-ion form. Additionally, we used the antenna effect to study PQQ and simultaneously Eu(III) in the active site.
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Affiliation(s)
- Nader Al Danaf
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstraße 5 - 13, 81377 München, Germany. .,Center for NanoScience, Ludwig-Maximilians-University Munich, Geschwister-Scholl Platz 1, 80539 München, Germany
| | - Jerome Kretzschmar
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - Berenice Jahn
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstraße 5 - 13, 81377 München, Germany.
| | - Helena Singer
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstraße 5 - 13, 81377 München, Germany.
| | - Arjan Pol
- Department of Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Huub J M Op den Camp
- Department of Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Robin Steudtner
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - Don C Lamb
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstraße 5 - 13, 81377 München, Germany. .,Center for NanoScience, Ludwig-Maximilians-University Munich, Geschwister-Scholl Platz 1, 80539 München, Germany
| | - Björn Drobot
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - Lena J Daumann
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstraße 5 - 13, 81377 München, Germany.
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14
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Storm Thomsen M, Anker AS, Kacenauskaite L, Sørensen TJ. We are never ever getting (back to) ideal symmetry: structure and luminescence in a ten-coordinated europium(III) sulfate crystal. Dalton Trans 2022; 51:8960-8963. [PMID: 35660819 DOI: 10.1039/d2dt01522f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Our theoretical treatment of electronic structures in coordination complexes often rests on assumptions of symmetry. Experiments rarely provide fully symmetric systems to study. In solutions, fluctuations in solvation, variations in conformations, and even changes in constitution occur and complicate the picture. In crystals, lattice distortion, energy transfer, and phonon quenching play a role, but we are able to identify distinct symmetries. Yet the question remains: How is the real symmetry in a crystal compared to ideal symmetries?
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Affiliation(s)
- Maria Storm Thomsen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Andy S Anker
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Laura Kacenauskaite
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Thomas Just Sørensen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
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15
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Kofod N, Storm Thomsen M, Nawrocki P, Sørensen TJ. Revisiting the assignment of innocent and non-innocent counterions in lanthanide(III) solution chemistry. Dalton Trans 2022; 51:7936-7949. [PMID: 35543234 DOI: 10.1039/d2dt00565d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Lanthanides are found in critical applications from display technology to renewable energy. Often, these rare earth elements are used as alloys or functional materials, yet access to them is through solution processes. In aqueous solutions, the rare earths are found predominantly as trivalent ions and charge balance dictates that counterions are present. The fast ligand exchange and lack of directional bonding in lanthanide complexes have led to questions regarding the speciation of Ln3+ solvates in the presence of various counterions and the distinction between innocent = non-coordinating and non-innocent = coordinating counterions. There is limited agreement as to which group counterions belong to, which led to this report. By using Eu3+ luminescence, it was possible to clearly distinguish between coordinating and non-coordinating ions. To interpret the results, it was required to bridge the descriptions of ion pairing and coordination. The data-in the form of Eu3+ luminescence spectra and luminescence lifetimes from solutions with varying concentrations of acetate, chloride, nitrate, sulfate, perchlorate and triflate-was contrasted to those obtained with ethylenediaminetetraacetic acid (EDTA4-), which allowed for the distinction between three Ln3+-anion interaction types. It was possible to conclude which counterions are truly innocent (e.g. ClO4- and OTf-) and which clearly coordinate (e.g. NO3- and AcO-). Finally, a considerable amount of data from systems studied under similar conditions allowed the minimum perturbation arising from the inner sphere or outer sphere coordination in Eu3+ complexes to be identified.
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Affiliation(s)
- Nicolaj Kofod
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Maria Storm Thomsen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Patrick Nawrocki
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
| | - Thomas Just Sørensen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
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16
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Kofod N, Nawrocki P, Sørensen TJ. Arel: Investigating [Eu(H 2O) 9] 3+ Photophysics and Creating a Method to Bypass Luminescence Quantum Yield Determinations. J Phys Chem Lett 2022; 13:3096-3104. [PMID: 35357175 DOI: 10.1021/acs.jpclett.2c00418] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Lanthanide luminescence has been treated separate from molecular photophysics, although the underlying phenomena are the same. As the optical transitions observed in the trivalent lanthanide ions are forbidden, they do belong to the group that molecular photophysics has yet to conquer, yet the experimental descriptors remain valid. Herein, the luminescence quantum yields (ϕlum), luminescence lifetimes (τobs), oscillator strengths (f), and the rates of nonradiative (knr) and radiative (kr ≡ A) deactivation of [Eu(H2O)9]3+ were determined. Further, it was shown that instead of a full photophysical characterization, it is possible to relate changes in transition probabilities to the relative parameter Arel, which does not require reference data. While Arel does not afford comparisons between experiments, it resolves emission intensity changes due to emitter properties from intensity changes due to environmental effects and differences in the number of photons absorbed. When working with fluorescence this may seem trivial; when working with lanthanide luminescence it is not.
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Affiliation(s)
- Nicolaj Kofod
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Patrick Nawrocki
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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17
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Storm Thomsen M, Parsons S, Sørensen TJ. Invisible strings. The first single crystal of the cTSAP form of [Eu(DOTA)(H 2O)] − has an electronic structure similar to one of the reported cSAP forms. Dalton Trans 2022; 51:15725-15733. [DOI: 10.1039/d2dt02633c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Counter ions can be used to tune the solid state structure of Eu·DOTA between the cSAP and cTSAP form, but the electronic properties does not match the observations seen in solution.
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Affiliation(s)
- Maria Storm Thomsen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Simon Parsons
- School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3FJ, Scotland, UK
| | - Thomas Just Sørensen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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18
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Storm Thomsen M, Sørensen TJ. Delicate, a study of the structural changes in ten-coordinated La( iii), Ce( iii), Pr( iii), Nd( iii), Sm( iii) and Eu( iii) sulfates. Dalton Trans 2022; 51:8964-8974. [DOI: 10.1039/d2dt00832g] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A study of doped ten-coordinated structures of the lanthanide(iii) crystals series, K6[Ln2(SO4)6] (Ln(iii) = La, Ce, Pr) and K5Na[Ln2(SO4)6] (Ln(iii) = Nd, Sm, Eu) to determine luminescence from Eu(iii) in distorted host lattices.
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Affiliation(s)
- Maria Storm Thomsen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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19
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Kofod N, Nielsen LG, Sørensen TJ. Temperature Dependence of Fundamental Photophysical Properties of [Eu(MeOH- d4) 9] 3+ Solvates and [Eu·DOTA(MeOH- d4)] - Complexes. J Phys Chem A 2021; 125:8347-8357. [PMID: 34546039 DOI: 10.1021/acs.jpca.1c04994] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(III) and europium(III) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(III). The photophysical properties of two complexes-[Eu·DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+-were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorbance as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as the temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in the non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated with a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorbance and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Furthermore, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called "Werts' method" for calculating radiative lifetimes and intrinsic quantum yields is based on assumptions that do not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transitions, and that there are still aspects of fundamental lanthanide photophysics to be explored.
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Affiliation(s)
- Nicolaj Kofod
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Lea Gundorff Nielsen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Thomas Just Sørensen
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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20
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Vetsova VA, Fisher KR, Lumpe H, Schäfer A, Schneider EK, Weis P, Daumann LJ. Pyrroloquinoline Quinone Aza-Crown Ether Complexes as Biomimetics for Lanthanide and Calcium Dependent Alcohol Dehydrogenases*. Chemistry 2021; 27:10087-10098. [PMID: 33872420 PMCID: PMC8361747 DOI: 10.1002/chem.202100346] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Indexed: 12/23/2022]
Abstract
Understanding the role of metal ions in biology can lead to the development of new catalysts for several industrially important transformations. Lanthanides are the most recent group of metal ions that have been shown to be important in biology, that is, in quinone‐dependent methanol dehydrogenases (MDH). Here we evaluate a literature‐known pyrroloquinoline quinone (PQQ) and 1‐aza‐15‐crown‐5 based ligand platform as scaffold for Ca2+, Ba2+, La3+ and Lu3+ biomimetics of MDH and we evaluate the importance of ligand design, charge, size, counterions and base for the alcohol oxidation reaction using NMR spectroscopy. In addition, we report a new straightforward synthetic route (3 steps instead of 11 and 33 % instead of 0.6 % yield) for biomimetic ligands based on PQQ. We show that when studying biomimetics for MDH, larger metal ions and those with lower charge in this case promote the dehydrogenation reaction more effectively and that this is likely an effect of the ligand design which must be considered when studying biomimetics. To gain more information on the structures and impact of counterions of the complexes, we performed collision induced dissociation (CID) experiments and observe that the nitrates are more tightly bound than the triflates. To resolve the structure of the complexes in the gas phase we combined DFT‐calculations and ion mobility measurements (IMS). Furthermore, we characterized the obtained complexes and reaction mixtures using Electron Paramagnetic Resonance (EPR) spectroscopy and show the presence of a small amount of quinone‐based radical.
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Affiliation(s)
- Violeta A Vetsova
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstraße 5-13, 81377, Munich, Germany
| | - Katherine R Fisher
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstraße 5-13, 81377, Munich, Germany
| | - Henning Lumpe
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstraße 5-13, 81377, Munich, Germany
| | - Alexander Schäfer
- Karlsruhe Institute of Technology, Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76128, Karlsruhe, Germany
| | - Erik K Schneider
- Karlsruhe Institute of Technology, Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76128, Karlsruhe, Germany
| | - Patrick Weis
- Karlsruhe Institute of Technology, Institute of Physical Chemistry, Fritz-Haber-Weg 2, 76128, Karlsruhe, Germany
| | - Lena J Daumann
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstraße 5-13, 81377, Munich, Germany
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21
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Mishra NK, Østergaard M, Midtgaard SR, Strindberg SS, Winkler S, Wu S, Sørensen TJ, Hassenkam T, Poulsen JCN, Lo Leggio L, Nielsen HM, Arleth L, Christensen NJ, Thulstrup PW, Jensen KJ. Controlling the fractal dimension in self-assembly of terpyridine modified insulin by Fe 2+ and Eu 3+ to direct in vivo effects. NANOSCALE 2021; 13:8467-8473. [PMID: 33984105 DOI: 10.1039/d1nr00414j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Metal ion-induced self-assembly (SA) of proteins into higher-order structures can provide new, dynamic nano-assemblies. Here, the synthesis and characterization of a human insulin (HI) analog modified at LysB29 with the tridentate chelator 2,2':6',2''-terpyridine (Tpy) is described. SA of this new insulin analog (LysB29Tpy-HI) in the presence of the metal ions Fe2+ and Eu3+ at different concentrations was studied in solution by fluorescence luminescence and CD spectroscopy, dynamic light scattering, and small-angle X-ray scattering, while surface assembly was probed by AFM. Unique oligomerization was observed in solution, as Fe2+ yielded small magenta-colored discrete non-native assemblies, while Eu3+ caused the formation of large fractal assemblies. Binding of both metal ions to Tpy was demonstrated spectroscopically, and emission lifetime experiments revealed a distinct Eu3+ coordination geometry that included two water molecules. SAXS suggested that LysB29Tpy-HI with Fe2+ oligomerized to a discrete, roughly octameric species, while LysB29Tpy-HI with Eu3+ gave very large assemblies that could be modelled as fractals. The fractal dimensionality increased with the Eu3+ concentration. We propose that this is a consequence of Eu3+ binding to both Tpy and to free carboxylic acid groups on the insulin surface. LysB29Tpy-HI maintained insulin receptor affinity, and showed extended blood glucose lowering and plasma concentration after subcutaneous injection in rats. The combination of metal ion directed SA and native SA provides control of nano-scale fractal dimensionality and points towards use in therapeutics.
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Affiliation(s)
- Narendra Kumar Mishra
- Center for Biopharmaceuticals and Biobarriers in Drug Delivery and Department of Chemistry, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
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22
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Kofod N, Nawrocki P, Platas-Iglesias C, Sørensen TJ. Electronic Structure of Ytterbium(III) Solvates-a Combined Spectroscopic and Theoretical Study. Inorg Chem 2021; 60:7453-7464. [PMID: 33949865 DOI: 10.1021/acs.inorgchem.1c00743] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The wide range of optical and magnetic properties of lanthanide(III) ions is associated with their intricate electronic structures which, in contrast to lighter elements, is characterized by strong relativistic effects and spin-orbit coupling. Nevertheless, computational methods are now capable of describing the ladder of electronic energy levels of the simpler trivalent lanthanide ions, as well as the lowest energy term of most of the series. The electronic energy levels result from electron configurations that are first split by spin-orbit coupling into groups of energy levels denoted by the corresponding Russell-Saunders terms. Each of these groups are then split by the ligand field into the actual electronic energy levels known as microstates or sometimes mJ levels. The ligand-field splitting directly informs on the coordination geometry and is a valuable tool for determining the structure and thus correlating the structure and properties of metal complexes in solution. The issue with lanthanide complexes is that the determination of complex structures from ligand-field splitting remains a very challenging task. In this paper, the optical spectra-absorption, luminescence excitation, and luminescence emission-of ytterbium(III) solvates were recorded in water, methanol, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF). The electronic energy levels, that is, the microstates, were resolved experimentally. Subsequently, density functional theory calculations were used to model the structures of the solvates, and ab initio relativistic complete active space self-consistent field calculations (CASSCF) were employed to obtain the microstates of the possible structures of each solvate. By comparing the experimental and theoretical data, it was possible to determine both the coordination number and solution structure of each solvate. In water, methanol, and N,N-dimethylformamide, the solvates were found to be eight-coordinated and have a square antiprismatic coordination geometry. In DMSO, the speciation was found to be more complicated. The robust methodology developed for comparing experimental spectra and computational results allows the solution structures of homoleptic lanthanide complexes to be determined.
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Affiliation(s)
- Nicolaj Kofod
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Patrick Nawrocki
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas and Departamento de Química, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Thomas Just Sørensen
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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23
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Arnedo-Sanchez L, Smith KF, Deblonde GJP, Carter KP, Moreau LM, Rees JA, Tratnjek T, Booth CH, Abergel RJ. Combining the Best of Two Chelating Titans: A Hydroxypyridinone-Decorated Macrocyclic Ligand for Efficient and Concomitant Complexation and Sensitized Luminescence of f-Elements. Chempluschem 2021; 86:483-491. [PMID: 33733616 DOI: 10.1002/cplu.202100083] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/02/2021] [Indexed: 12/11/2022]
Abstract
An ideal chelator for f-elements features rapid kinetics of complexation, high thermodynamic stability, and slow kinetics of dissociation. Here we present the facile synthesis of a macrocyclic ligand bearing four 1-hydroxy-2-pyridinone units linked to a cyclen scaffold that rapidly forms thermodynamically stable complexes with lanthanides (Sm3+ , Eu3+ , Tb3+ , Dy3+ ) and a representative late actinide (Cm3+ ) in aqueous media and concurrently sensitizes them. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed an increase in the Ln/An-O bond lengths following the trend Cm>Eu>Tb and EXAFS data were compatible with time-resolved luminescence studies, which indicated one to two water molecules in the inner metal coordination sphere of Eu(III) and two water molecules for the Cm(III) complex. Spectrofluorimetric ligand competition titrations against DTPA confirmed the high thermodynamic stability of DOTHOPO complexes, with pM values between 19.9(1) and 21.9(2).
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Affiliation(s)
- Leticia Arnedo-Sanchez
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Kurt F Smith
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Gauthier J-P Deblonde
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Korey P Carter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Liane M Moreau
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Julian A Rees
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Toni Tratnjek
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Corwin H Booth
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Rebecca J Abergel
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Department of Nuclear Engineering, University of California, Berkeley, CA 94709, USA
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24
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New Coumarin Dipicolinate Europium Complexes with a Rich Chemical Speciation and Tunable Luminescence. Molecules 2021; 26:molecules26051265. [PMID: 33652775 PMCID: PMC7956443 DOI: 10.3390/molecules26051265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/20/2021] [Accepted: 02/22/2021] [Indexed: 11/25/2022] Open
Abstract
Europium (III) luminescent chelates possess intrinsic photophysical properties that are extremely useful in a wide range of applications. The lack of examples of coumarin-based lanthanide complexes is mainly due to poor photo-sensitization attempts. However, with the appeal of using such a versatile scaffold as antenna, especially in the development of responsive molecular probes, it is worth the effort to research new structural motifs. In this work, we present a series of two new tris coumarin-dipicolinate europium (III) complexes, specifically tailored to be either a mono or a dual emitter, tuning their properties with a simple chemical modification. We also encountered a rich chemical speciation in solution, studied in detail by means of paramagnetic NMR and emission spectroscopy.
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25
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Deblonde GJP. Spectrophotometric methods to probe the solution chemistry of lanthanide complexes with macromolecules. Methods Enzymol 2021; 651:1-22. [PMID: 33888200 DOI: 10.1016/bs.mie.2020.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Lanthanide biochemistry has experienced a revival in recent years owing to the discovery of new biomolecular platforms that are amenable to bind, sequester, or transport lanthanide ions. This has inherently created a need for physicochemical methods that report on lanthanide-containing macromolecular systems. In this chapter, the use of spectrophotometric methods to study the stability of lanthanide-macromolecule complexes in solution is discussed. Indeed, lanthanide ions have unique spectral properties in the ultraviolet, visible, and near-infrared domains that set them apart from the more common elements encountered in biochemistry, and these unique features can be leveraged to study, in a quantitative and robust manner, the solution chemistry of their biorelevant species (Kd, pH stability, temperature profile, etc.). This chapter aims at bringing a method that has been established and validated in the small molecule chemistry field to this new era of lanthanide biochemistry.
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Affiliation(s)
- Gauthier J-P Deblonde
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States.
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26
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Andres J, Chauvin AS. Colorimetry of Luminescent Lanthanide Complexes. Molecules 2020; 25:molecules25174022. [PMID: 32899208 PMCID: PMC7570272 DOI: 10.3390/molecules25174022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022] Open
Abstract
Europium, terbium, dysprosium, and samarium are the main trivalent lanthanide ions emitting in the visible spectrum. In this work, the potential of these ions for colorimetric applications and colour reproduction was studied. The conversion of spectral data to colour coordinates was undertaken for three sets of Ln complexes composed of different ligands. We showed that Eu is the most sensitive of the visible Ln ions, regarding ligand-induced colour shifts, due to its hypersensitive transition. Further investigation on the spectral bandwidth of the emission detector, on the wavelengths’ accuracy, on the instrumental correction function, and on the use of incorrect intensity units confirm that the instrumental correction function is the most important spectrophotometric parameter to take into account in order to produce accurate colour values. Finally, we established and discussed the entire colour range (gamut) that can be generated by combining a red-emitting Eu complex with a green-emitting Tb complex and a blue fluorescent compound. The importance of choosing a proper white point is demonstrated. The potential of using different sets of complexes with different spectral fingerprints in order to obtain metameric colours suitable for anti-counterfeiting is also highlighted. This work answers many questions that could arise during a colorimetric analysis of luminescent probes.
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Affiliation(s)
- Julien Andres
- Section of Chemistry and Chemical Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Correspondence: (J.A.); (A.-S.C.); Tel.: +41-21-693-7455 (J.A.); +41-21-693-9824 (A.-S.C.)
| | - Anne-Sophie Chauvin
- Section of Chemistry and Chemical Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Institut des Sciences et Ingénierie Chimique, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Correspondence: (J.A.); (A.-S.C.); Tel.: +41-21-693-7455 (J.A.); +41-21-693-9824 (A.-S.C.)
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