Fluoride Binding and Crystal‐Field Analysis of Lanthanide Complexes of Tetrapicolyl‐Appended Cyclen

Blackburn, Octavia A.; Kenwright, Alan M.; Jupp, Andrew R.; Goicoechea, José M.; Beer, Paul D.; Faulkner, Stephen

doi:10.1002/chem.201601170

Cited by 34 publications

(21 citation statements)

References 40 publications

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“…Analysis of the crystal structure reveals that the high association constant (log Ka = 13.0) can be explained by stabilisation of the dimer by four hydrogen bonds formed between the nitrogen atoms of the indazole moiety of one complex and the oxygen atoms of the carboxylate arms of another, as well as by formation of a Eu----F ------Eu bond. A symmetric europium complex [Eu.11] 3+ based on the cyclen core with four pyridyl substituents was analysed by Faulkner [28] , revealing a high affinity towards F --(log Ka = 5.0). Since no competitive binding studies have been carried out, the selectivity of the proposed complex towards fluoride ions remains unclear, although additional stabilisation of F --might be expected via formation of hydrogen bonds with the nitrogen atoms of the pyridyl groups.…”

Section: Sensing Of Biologically Relevant Anionsmentioning

confidence: 99%

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Shuvaev

Starck

Parker

2017

Chemistry A European J

112

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: Sensing Of Biologically Relevant Anionsmentioning

confidence: 99%

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Shuvaev

Starck

Parker

2017

Chemistry A European J

112

103

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“…2 Spin-crossover materials, which have been intensively studied for many years, 3 have been proposed for applications in displays, sensors and information storage devices. 4 Lanthanide complexes continue to play important roles in enhancing our understanding of ligand field theory, 5 and many such species find applications in NMR spectroscopy as shift reagents 6 and in magnetic resonance imaging. 7 …”

Section: Introductionmentioning

confidence: 99%

Antimony-ligated dysprosium single-molecule magnets as catalysts for stibine dehydrocoupling

2017

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“…The line shape and branching ratio in the emission spectrum of a lanthanide ion in solution changes according to the symmetry and donor set of the coordination environment, as well as with changes in the surrounding solution. [34][35][36][37][38][39] Thus, the solution structure of a lanthanide containing system can be probed by luminescence spectroscopy, 24,40 and the solution composition may be investigated by observing changes in the lanthanide centered luminescence. [41][42] A pre-requisite for using lanthanide complexes as contrast agents is that the toxic lanthanide ions are not released and subsequently accumulated in the patient.…”

Section: Introductionmentioning

confidence: 99%

Kinetically Inert Lanthanide Complexes as Reporter Groups for Binding of Potassium by 18-crown-6

et al. 2016

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The barcode-like spectrum of lanthanide-centered emission has been used in imaging and to make responsive luminescent reporters. The intensities and the shapes of each line in the luminescence spectrum can also report on the coordination environment of the lanthanide ion. Here, we used lanthanide-centered emission to report on the binding of potassium in an 18-crown-6 binding pocket. The responsive systems were made by linking a crown ether to a kinetically inert lanthanide binding pocket using a molecular building block approach. Specifically, an alkyne-appended Ln.DO3A was used as a building block in a copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) "click" reaction with azide-functionalized crown ethers. The resulting complexes were investigated using NMR and optical methods. Titrations with potassium chloride in methanol observing the sensititzed europium- and terbium-centered emissions were used to investigate the response of the systems. The molecular reporters based on aliphatic crown ethers were found to have strongly inhibited binding of potassium, while the benzo-18-crown-6 derived systems had essentially the same association constants as the native crown ethers. The shape of the lanthanide emission spectra was shown to be unperturbed by the binding of potassium, while the binding was reported by an overall increased intensity of the lanthanide-centered emission. This observation was contrasted to the change in spectral shape between propargyl-Ln.DO3A and the triazolyl-Ln.DO3A complexes. The solution structure of the lanthanide complexes was found to be determining for the observed physical chemical properties of these systems.

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Fluoride Binding and Crystal‐Field Analysis of Lanthanide Complexes of Tetrapicolyl‐Appended Cyclen

Cited by 34 publications

References 40 publications

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Responsive, Water‐Soluble Europium(III) Luminescent Probes

Antimony-ligated dysprosium single-molecule magnets as catalysts for stibine dehydrocoupling

Kinetically Inert Lanthanide Complexes as Reporter Groups for Binding of Potassium by 18-crown-6

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