Electrochemical Study of the Eu<sup>III</sup>/Eu<sup>II</sup> Redox Properties of Complexes with Potential MRI Ligands

Gál, Miroslav; Kielar, Filip; Sokolová, Romana; Ramešová, Šárka; Kolivoška, Viliam

doi:10.1002/ejic.201300252

Cited by 31 publications

(9 citation statements)

References 55 publications

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“…The reduction potential for Eu 3+ /Eu 2+ is the lowest in the lanthanide series, e.g. --0.35 V for the aqua ion, and about --1.1 V for Eu(III) complexes with many strongly coordinating octadentate ligands that stabilise Eu(III) with respect to Eu(II) [4], [5] . The energy of these broad LMCT bands, with widths in the range 5000--15000 cm --1 , varies considerably depending on the electron--donating ability of the ligand [6] .…”

Section: Introductionmentioning

confidence: 98%

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Shuvaev

Starck

Parker

2017

Chemistry A European J

117

103

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. E-mail: david.parker@dur.ac.uk; sergey.shuvaev@dur.ac.uk Abstract: The design principles, mechanism of action and performance of europium(III) complexes that serve as strongly emissive and responsive molecular probes in water are critically discussed. Examples of systems designed to assess pH, selected metal ions and anions, including chiral species, as well as selected small molecules and biopolymers are considered, and prospects evaluated for improved performance in more complex biological media such as in bio--fluids and within living cells. Modulation of the emission spectral form, lifetime and degree of circular polarisation can be used to quantify the spectral response and permit calibration. IntroductionThe genesis of lanthanide bio--imaging probes can be traced to two discoveries: the observation of the red emission of europium by Crookes in 1885 and the report of its sensitised emission made by Weissman in 1942 [1] . Each discovery epitomises the advantageous optical features of lanthanide complexes - narrow bands in emission with energies only slightly affected by the nature of the ligand, and a large separation (a "pseudo--Stokes' shift") between the absorbing (ligand--antenna) and emitting (lanthanide ion) photon energies. These favourable optical properties create a myriad of opportunities to devise responsive systems by judicious ligand design. Europium(III) complexes have particular advantages over other lanthanide complexes in biologically relevant applications: the higher transparency of biological tissue towards the red region of the visible spectrum; their high inherent brightness and low sensitivity to quenching by oxygen; the presence of three excited states ( 5 D2, 5 D1 and 5 D0) spanning the range 17500--21000 cm --1 that are lower in energy than the triplet levels of many different types of ligands; the presence of an environmentally insensitive magnetic--dipole transition 5 D0 to 7 F1 in the luminescence spectrum, (Figure 1), that can be used as an internal reference to the hypersensitive transition bands around 620 ( 5 D0 --7 F2) and 700 nm ( 5 D0 to 7 F4), and the high emission anisotropy factors, gem, in circularly polarised luminescence (CPL) spectra.

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Section: Introductionmentioning

confidence: 98%

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Shuvaev

Starck

Parker

2017

Chemistry A European J

117

103

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“…The ability of Eu II -222 to impart oxidative stabilization of the +2 oxidation state of europium has been studied (28,29), and recent reports have characterized the aqueous magnetic and electrochemical properties of Eu II -222 and other Eu II -containing complexes (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(30)(31)(32)(33). Despite increased oxidative stability, the Eu II ion of Eu II -222 is prone to rapid oxidation by oxygen in solution (18).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Eu^II‐based positive contrast enhancement after intravenous, intraperitoneal, and subcutaneous injections

Ekanger

Polin

Shen

et al. 2016

Contrast Media & Molecular

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EuII-based contrast agents offer physiologically relevant, metal-based redox sensing that is unachievable with GdIII-based contrast agents. To evaluate the in vivo contrast enhancement of EuII as a function of injection type, we performed intravenous, intraperitoneal, and subcutaneous injections in mice. Our data reveal a correlation between reported oxygen content and expected rates of diffusion with the persistence of EuII-based contrast enhancement. Biodistribution studies revealed europium clearance through the liver and kidneys for intravenous and intraperitoneal injections, but no contrast enhancement was observed in organs associated with clearance. These data represent a step toward understanding the behavior of EuII-based complexes in vivo.

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“…One of the current limitations of Eu II -containing complexes is their tendency to oxidize to Eu III in the presence of air. While some work has been done to overcome this effect, 57,58 further investigations are required to understand the in vivo outcomes of the oxidized products.…”

Section: Introductionmentioning

confidence: 99%

Enhancing magnetic resonance imaging with contrast agents for ultra-high field strengths

Kuda-Wedagedara

Allen

2014

Analyst

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Contrast agents are diagnostic tools that often complement magnetic resonance imaging. At ultra-high field strengths (≥7 T), magnetic resonance imaging is capable of generating desirable high signal-to-noise ratios, but clinically available contrast agents are less effective at ultra-high field strengths relative to lower fields. This gap in effectiveness demands the development of contrast agents for ultra-high field strengths. In this minireview, we summarize contrast agents reported during the last three years that focused on ultra-high field strengths.

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Electrochemical Study of the Eu^III/Eu^II Redox Properties of Complexes with Potential MRI Ligands

Cited by 31 publications

References 55 publications

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Evaluation of Eu^II‐based positive contrast enhancement after intravenous, intraperitoneal, and subcutaneous injections

Enhancing magnetic resonance imaging with contrast agents for ultra-high field strengths

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Electrochemical Study of the EuIII/EuII Redox Properties of Complexes with Potential MRI Ligands

Cited by 31 publications

References 55 publications

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Evaluation of EuII‐based positive contrast enhancement after intravenous, intraperitoneal, and subcutaneous injections

Enhancing magnetic resonance imaging with contrast agents for ultra-high field strengths

Contact Info

Product

Resources

About

Electrochemical Study of the Eu^III/Eu^II Redox Properties of Complexes with Potential MRI Ligands

Evaluation of Eu^II‐based positive contrast enhancement after intravenous, intraperitoneal, and subcutaneous injections