Azaxanthones and azathioxanthones are effective sensitisers for europium and terbium luminescence

Atkinson, Paul H.; Findlay, Karen S.; Kielar, Filip; Pál, Róbert; Parker, David; Poole, Robert A.; Puschmann, Horst; Richardson, Siobhan L.; Stenson, Philip A.; Thompson, Amber L.; Yu, Junhua

doi:10.1039/b601357k

Cited by 69 publications

(72 citation statements)

References 44 publications

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“…In each case, minimal ligand fluorescence was seen, consistent with observations made previously for other cyclen-based lanthanide complexes including 1-azaxanthone derivatives as the sensitising moiety. 138 The emission spectral profile observed for the two europium complexes was extremely similar, with slight differences apparent in the relative intensity of the various emission bands, particularly within the hypersensitive ΔJ = 2 and ΔJ = 4 manifolds. Meanwhile, for the terbium complexes, the spectral form of the metal-based emission was found to show a striking resemblance.…”

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confidence: 86%

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

2012

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The 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 Durham E-Theses• the full-text is not changed in any wayThe full-text must not be sold in any format or medium without the formal permission of the copyright holders. Statement of CopyrightThe copyright of this thesis rests with the author. No quotations should be published without prior consent and information derived from it must be acknowledged. ABSTRACT -ii - ABSTRACTA series of studies has been undertaken to facilitate the identification and development of chiral lanthanide complexes that are able to report on changes in their local environment through modulation of the circular polarization of their emission. Reports of such systems remain relatively rare in the literature, notwithstanding the prevalence and importance of chirality in biological systems.The work described herein is separated into five chapters, the first of which comprises a discussion of relevant background information, along with a comprehensive review of responsive lanthanide-based CPL probes reported to date. A classification of these probes is built up, which informs the content of the following three chapters.Chapter 2 describes work undertaken in the pursuit of a novel lanthanide-based system for use as a CPL probe for the detection of proteins. The synthesis of an enantiopure lanthanide complex was undertaken and characterisation of this system carried out with reference to a structurally related racemic complex. A series of comparative investigations designed to probe the relative protein binding capability of these complexes was subsequently performed, which revealed that the observation of induced CPL from racemic lanthanide systems may be brought about by a change in complex constitution. This is the first example of such an effect from a well-defined racemic lanthanide complex in solution. Chapter 3 goes on to detail studies undertaken to demonstrate the utility of this racemic lanthanide system as a probe for chiral detection.Chapter 4 describes investigations carried out in an attempt to identify new systems exhibiting chiral quenching effects in solution. Initially, two pairs of enantiomeric electron-rich quenching species were assessed for their ability to quench the emission from an enantiopure DOTA-derived lanthanide complex differentially. Subsequently, investigations were focussed on examining the quenching of emission from novel enantiopure lanthanide complexes based on a 1,4,7-triazacyclononane framework, using cobalt complexes as the quenching species.Finally, Chapter 5 contains experimental procedures for each compound synthesised, as well as general experimental procedures.

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confidence: 86%

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

2012

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“…The molar absorption coefficient at the maximum of absorption is around 8. . [69] The only drawback of the described stains is the relatively low excitation wavelength needed (even if confocal images can also be obtained upon excitation at 405 nm), although this can potentially be overcome by two-photon excitation.…”

Section: C3mentioning

confidence: 98%

A Versatile Ditopic Ligand System for Sensitizing the Luminescence of Bimetallic Lanthanide Bio‐Imaging Probes

Chauvin

Comby

Song

et al. 2008

Chemistry A European J

109

106

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The homoditopic ligand 6,6'-[methylenebis(1-methyl-1H-benzimidazole-5,2-diyl)]bis(4-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}pyridine-2-carboxylic acid) (H(2)L(C2)) has been tailored to self-assemble with lanthanide ions (Ln(III)), which results in the formation of neutral bimetallic helicates with the overall composition [Ln(2)(L(C2))(3)] and also provides a versatile platform for further derivatization. The grafting of poly(oxyethylene) groups onto the pyridine units ensures water solubility, while maintaining sizeable thermodynamic stability and adequate antenna effects for the excitation of both visible- and NIR-emitting Ln(III) ions. The conditional stability constants (log beta(23)) are close to 25 at physiological pH and under stoichiometric conditions. The ligand triplet state features adequate energy (0-phonon transition at approximately 21 900 cm(-1)) to sensitize the luminescence of Eu(III) (Q=21 %) and Tb(III) (11 %) in aerated water at pH 7.4. The emission of several other VIS- and NIR-emitting ions, such as Sm(III) (Q=0.38 %) or Yb(III) (0.15 %), for which in cellulo luminescence is evidenced for the first time, is also sensitized. The Eu(III) emission spectrum arises from a main species with pseudo-D(3) symmetry and without coordinated water. The cell viability of several cancerous cell lines (MCF-7, HeLa, Jurkat and 5D10) is unaffected if incubated with up to 500 microM [Eu(2)(L(C2))(3)] during 24 h. Bright Eu(III) emission is seen for incubation concentrations above 10 microM and after a 15-minute loading time; similar images are obtained with Tb(III) and Sm(III). The helicates probably permeate into the cytoplasm of HeLa cells by endocytosis. The described luminescent helical stains are robust chemical species which remain undissociated in the cell medium and in presence of other complexing agents, such as edta, dtpa, citrate or L-ascorbate. Their derivatization, which would open the way to the sensing of targeted in cellulo phenomena, is currently under investigation.

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“…[16] For the Eu complexes of L 1 to L 4 , a rather broad absorption band was observed around 329 nm. Increasing the number of azaxanthone groups increased the overall extinction coefficient of the complex.…”

Section: Introductionmentioning

confidence: 98%

“…[11,[13][14][15] The number of sensitising moieties included in mononuclear systems is determined by consideration of ligand denticity, and by the steric demands imposed by its constitution and the size of any substituents. Amongst a plethora of such sensitising chromophores, azaxanthones have been examined recently as sensitisers [5,9,[16][17] and have been integrated into a variety of ligands. They possess a weakly basic pyridyl nitrogen that can coordinate to the metal centre.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of the Luminescence Properties and Relative Stability of a Series of Europium(III) Complexes Bearing One to Four Coordinated Azaxanthone Groups

et al. 2010

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The synthesis and spectral properties are reported of a set of four europium(III) complexes containing between one and four 3‐azaxanthone sensitising chromophores. Each complex is based on a macrocyclic cyclen core. The emission and aqueous solution 1H NMR spectral properties are compared, revealing information about the local complex symmetry on the experimental timescale. A C2‐symmetric mono‐cationic complex shows an overall emission quantum yield of 10 % in HEPES buffer and exhibits the best relative stability profile in the presence of a million‐fold excess of added metal salts or EDTA, as indicated by the time‐dependence of overall europium emission, following indirect excitation of the 3‐azaxanthone chromophore.

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Azaxanthones and azathioxanthones are effective sensitisers for europium and terbium luminescence

Cited by 69 publications

References 44 publications

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

A Versatile Ditopic Ligand System for Sensitizing the Luminescence of Bimetallic Lanthanide Bio‐Imaging Probes

Comparative Study of the Luminescence Properties and Relative Stability of a Series of Europium(III) Complexes Bearing One to Four Coordinated Azaxanthone Groups

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