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(A) Reaction scheme of Tb(L3) (10 μM) reacting with 100 equiv. Na2S (1 mM) to form Tb(L4) in situ. (B) Emission spectra over time upon reduction of 10 nmol (10 μM) Tb(L3) (523 nm peak = scattering). (C) Fold-increase of emission over 5.5 hours. (D) Relative fold-change of emission of 10 nmol (10 μM) Tb(L3) in response to NaOAc, NaI, NaHCO3, NaCl, Na2SO4, Cys, and Na2S (100 equiv.) in PBS (dashed line = 1; error bars represent standard deviation, n = 3)
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![Structures of previously investigated complexes [Tb(L1)]⁻ and...](publication/352387815/figure/fig2/AS:11431281182921478@1692637744749/Structures-of-previously-investigated-complexes-TbL1-and-TbL2-leading-to-the_Q320.jpg)
Luminescent lanthanides possess ideal properties for biological imaging, including long luminescent lifetimes and emission within the optical window. Here, we report a novel approach to responsive luminescent Tb(iii) probes that involves direct modulation of the antenna excited triplet state energy. If the triplet energy lies too close to the 5D4 T...
Citations
... The change of absorption is, however, not a unique parameter to be considered when designing luminescent Ln 3 + -based responsive probes; Ln 3 + sensitization efficiencies provided by organic chromophores can also be modified in response to a stimulus. [44] Excitation spectra recorded upon monitoring the main Eu 3 + and Yb 3 + transitions at 615 and 980 nm, respectively, match the shapes of the absorption spectra, indicating that sensitization of both Ln 3 + ions occurs through the electronic states localized on the chromophoric ligands (Figures 2d-f and S127d-f). Upon excitation into the respective ligandcentered absorption bands in the range 260-310 nm, Eu 3 + and Yb 3 + complexes exhibit their characteristic narrow emission bands in the visible (Eu 3 + ) or in the NIR (Yb 3 + ) range. ...
Applying a single molecular probe to monitor enzymatic activities in multiple, complementary imaging modalities is highly desirable to ascertain detection and to avoid the complexity associated with the use of agents of different chemical entities. We demonstrate here the versatility of lanthanide (Ln³⁺) complexes with respect to their optical and magnetic properties and their potential for enzymatic detection in NIR luminescence, CEST and T1 MR imaging, controlled by the nature of the Ln³⁺ ion, while using a unique chelator. Based on X‐ray structural, photophysical, and solution NMR investigations of a family of Ln³⁺ DO3A‐pyridine model complexes, we could rationalize the luminescence (Eu³⁺, Yb³⁺), CEST (Yb³⁺) and relaxation (Gd³⁺) properties and their variations between carbamate and amine derivatives. This allowed the design of LnLGal5 ${{{\bf L n L}}_{{\bf G a l}}^{5}}$ probes which undergo enzyme‐mediated changes detectable in NIR luminescence, CEST and T1‐weighted MRI, respectively governed by variations in their absorption energy, in their exchanging proton pool and in their size, thus relaxation efficacy. We demonstrate that these properties can be exploited for the visualization of β‐galactosidase activity in phantom samples by different imaging modalities: NIR optical imaging, CEST and T1‐weighted MRI.
... One obstacle to the theoretical molecular design of new rare earth metal complexes is their ambiguous structure [14][15][16]. To satisfy the high coordination numbers typical for rare earth ions, up to 12, lanthanoids can form complexes with metal-to-antennae ligands ratios of 1:1, 1:2, 1:3, etc. ...
The luminescent metal-organic complexes of rare earth metals are advanced materials with wide application potential in chemistry, biology, and medicine. The luminescence of these materials is due to a rare photophysical phenomenon called antenna effect, in which the excited ligand transmits its energy to the emitting levels of the metal. However, despite the attractive photophysical properties and the intriguing from a fundamental point of view antenna effect, the theoretical molecular design of new luminescent metal-organic complexes of rare earth metals is relatively limited. Our computational study aims to contribute in this direction, and we model the excited state properties of four new phenanthroline-based complexes of Eu(III) using the TD-DFT/TDA approach. The general formula of the complexes is EuL 2 A 3 , where L is a phenanthroline with-2-CH 3 O-C 6 H 4 ,-2-HO-C 6 H 4 ,-C 6 H 5 or-O-C 6 H 5 substituent at position 2 and A is Cl − or NO 3 −. The antenna effect in all newly proposed complexes is estimated as viable and is expected to possess luminescent properties. The relationship between the electronic properties of the isolated ligands and the luminescent properties of the complexes is explored in detail. Qualitative and quantitative models are derived to interpret the ligand-to-complex relation, and the results are benchmarked with respect to available experimental data. Based on the derived model and common molecular design criteria for efficient antenna ligands, we choose phenanthroline with-O-C 6 H 5 substituent to perform complexation with Eu(III) in the presence of NO 3. Experimental results for the newly synthesized Eu(III) complex are reported with a luminescent quantum yield of about 24% in acetonitrile. The study demonstrates the potential of low-cost computational models for discovering metal-organic luminescent materials.
... [15][16][17][18][19] This can be -and has been -used extensively to create lanthanide(III) complexes with a response specific to an analyte. [7,[20][21][22][23][24][25][26][27][28][29] The basis of the response is a lanthanide(III) centred interaction between the analyte molecule, or guest, and the lanthanide(III) complex which acts as host, and we are not able to describe these supramolecular interactions to an adequate degree. Here, we aim to lay the foundation for linear free energy relationships for lanthanide(III) centred interactions as we know them from supramolecular chemistry. ...
Responsive lanthanide(III) complexes – europium(III) complexes in particular – have been the focus of studies for several decades. While responsive lanthanide complexes have been reported and investigated frequently, the supramolecular aspects and linear free‐energy relationship have seen less attention. Here, we are revisiting five europium(III) complexes and investigating their binding to ten different guests, all with a primary interaction between the europium(III) ion and a bidentate carboxylate anion. The studies consisted of measuring emission spectra, analysing band behaviours of the europium transitions, and calculating lifetime isotherms. The media effect was also investigated, and by eliminating the impact of hydrophobic effects, we can show that selectivity in these host‐guest systems can be tuned by the secondary lipophilic interactions.
... [15][16][17][18][19] This can be-and has been-used extensively to create lanthanide(III) complexes with a response specific to an analyte. 7,[20][21][22][23][24][25][26][27][28][29] The basis of the response is a lanthanide(III) centred interaction, which we are not able to describe to an adequate degree. Here, we aim to lay the foundation for linear free energy relationships for lanthanide(III) centred interactions as we know them from supramolecular chemistry. ...
Responsive lanthanide(III) complexes—europium(III) complexes in particular—has been the focus of studies for several decades. The response, in the form of changes of photophysical and electronic properties of the lanthanide(III) ion, arises through supramolecular interactions between a guest or analyte molecule, and the lanthanide(III) complex which acts as host. While responsive lanthanide complexes have been reported and investigated frequently, the supramolecular aspects and linear free-energy relationship have had less attention. Here, we are revising five europium(III) complexes and investigating their binding to nine different guests, all with a primary interaction between europium(III) ion and a bidentate carboxylate anion. The media effect was investigated, and by eliminating the impact of hydrophobic effects, we can show that selectivity in these host-guest systems can be tuned by the secondary lipophilic interactions.
Applying a single molecular probe to monitor enzymatic activities in multiple, complementary imaging modalities is highly desirable to ascertain detection and to avoid the complexity associated with the use of agents of different chemical entities. We demonstrate here the versatility of lanthanide (Ln3+) complexes with respect to their optical and magnetic properties and their potential for enzymatic detection in NIR luminescence, CEST and T1 MR imaging, controlled by the nature of the Ln3+ ion, while using a unique chelator. Based on X‐ray structural, photophysical, and solution NMR investigations of a family of Ln3+ DO3A‐pyridine model complexes, we could rationalize the luminescence (Eu3+, Yb3+), CEST (Yb3+) and relaxation (Gd3+) properties and their variations between carbamate and amine derivatives. This allowed the design of probes which undergo enzyme‐mediated changes detectable in NIR luminescence, CEST and T1‐weighted MRI, respectively governed by variations in their absorption energy, in their exchanging proton pool and in their size, thus relaxation efficacy. We demonstrate that these properties can be exploited for the visualization of b‐galactosidase activity in phantom samples by different imaging modalities: NIR optical imaging, CEST and T1‐weighted MRI.
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...
Since their discovery in 1966, scorpionate ligands have been utilized to make coordination compounds for a variety of applications such as: studying organometallic reactions, biomimetic complexes, light-emitting materials and single-ion magnets. The recent development of a solvent-free pyrazole substitution chemistry has yielded the quantitative synthesis of asymmetrically functionalized all-pyrazole heteroscorpionate ligands. In this frontier article, we highlight the utility of all-pyrazole heteroscorpionates, specifically, nitro-trispyrazolylborates, in f-element chemistry. They offer great versatility in coordinating ability, donor strength, steric bulk and even optical charge transfer properties, all of which can be used to tune the properties of resultant complexes with metal ions. We show how they can impart structural diversity, sensitize Ln3+ luminescence and engender magnetic anisotropy and slow magnetic relaxation in the ion they coordinate. Additionally, we comment on the future of functionalized trispyrazolyl scorpionates, which includes enabling post-synthetic modifications of f-element complexes and becoming a platform to study the electronic properties of low oxidation state actinides.
Aliphatic triplet carbonyls can be treated as short-lived radicals, since both species share similar reactions such as hydrogen atom abstraction, cyclization, addition, and isomerization. Importantly, enzyme-generated triplet carbonyls excite triplet molecular oxygen to the highly reactive, electrophilic singlet state by resonance energy transfer, which can react with proteins, lipids, and DNA. Carbonyl triplets, singlet oxygen, and radicals are endowed with the potential to trigger both normal and pathological responses. In this paper, we present a short review of easy, fast, and inexpensive preliminary tests for the detection of transient triplet carbonyls in chemical and biological systems. This paper covers direct and indirect methods to look for triplet carbonyls based on their spectral distribution of chemiluminescence, photoproduct analysis, quenching of light emission by conjugated dienes, and enhancement of light emission by the sensitizer 9,10-dibromoanthracence-2-sulfonate ion (DBAS).
