Solution Equilibria in YbDOTMA, a Chiral Analogue of One of the Most Successful Contrast Agents for MRI, GdDOTA

Bari, Lorenzo Di; Pintacuda, Guido; Salvadori, Piero

doi:10.1002/(sici)1099-0682(200001)2000:1<75::aid-ejic75>3.0.co;2-#

Cited by 40 publications

(68 citation statements)

References 22 publications

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“…78,79 Meanwhile, the integration of chirality into the pendant arms will generally inhibit arm rotation. [80][81][82] Due to the fact that all lanthanide complexes derived from a DOTA framework will show preference towards either a SAP or TSAP geometry, the implementation of only one of the strategies outlined above will normally lead to the preferential formation of a single …”

Section: 67mentioning

confidence: 99%

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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Section: 67mentioning

confidence: 99%

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

2012

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“…1 H EXSY showed that exchange occurs exclusively through inversion of the ring conformation, as pendant arm rotation is strongly hindered by the methyl substitution. NOE data unequivocally assigned the "major" form to the (λλλλ) (eight-coordinate TSA ) configuration and the "minor" form to (δδδδ) (nine-coordinate SA) [317]. The R chirality of the methyl acetate pendant arm in Yb(DOTMA) − determines the helicity of the pendant arms, as the bulky methyl group must be anti to Yb with respect to the C-N bond.…”

Section: Dota and Derivativesmentioning

confidence: 99%

Structure, Dynamics, and Computational Studies of Lanthanide‐Based Contrast Agents

Peters

Djanashvili

Geraldes

et al. 2013

The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging

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“…The main principal component for Yb1 is about 5800, while for Yb2 it is 3200, in close analogy with the two forms (SAP and TSAP) of YbDOTA and YbDOTMA. 7,15 As was observed for YbDOTA and YbDOTMA, 7,11 the proportionality between the shifts of Yb1 and Yb2 implies that the same set of geometrical factors may fit both spectra. In the present case, however, the presence of substituents on both the cyclen ring and the pendant arms removes any ambiguity.…”

Section: Analysis Of the Paramagnetic Nmr Shiftsmentioning

confidence: 99%

“…This observation has important implications for our previous results examining the NIR-CD of YbDOTMA. 7 (RRRR)-YbDOTMA exists as an equilibrium mixture of two coordination isomers; the Λ(λλλλ), a TSAP isomer, and the Λ(δδδδ), a SAP isomer. From the 1 H NMR spectrum (Figure 3), it can be seen that the TSAP isomer composes about 95% of an aqueous solution of the complex.…”

Section: Near-infrared Circular Dichroism (Nir-cd) Spectroscopymentioning

confidence: 99%

“…With these reservations in mind, the spectrum of (RRRR)-YbDOTMA had previously been ascribed to its major form only and the individual transitions assigned on the basis of temperature-dependent studies. 7 The spectrum of (RRRR)-YbDOTMA is shown on the same axes as that of Yb2 ( Figure 6). The two spectra are almost prefect mirror images of one another, a result that was predicted by the opposing conformations of the coordination geometries, Λ(λλλλ) and Δ(δδδδ) for Yb2 and YbDOTMA, respectively.…”

Section: Near-infrared Circular Dichroism (Nir-cd) Spectroscopymentioning

confidence: 99%

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Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

et al. 2005

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Studies of the structural, physical, and chemical properties of the lanthanide(III) complexes of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and related ligands are often complicated by the presence of two coordination isomers in solution. Since these coordination isomers are in exchange and cannot be separated, many techniques offer information only on the weighted average of the two isomers. Lanthanide ion complexes formed with the ligands S(RRRR)NO 2 BnDOTMA and S(SSSS)NO 2 BnDOTMA preferentially adopt only one of the two common coordination isomers in solution, so the ytterbium complexes of these ligands offer a unique opportunity to study the nearinfrared circular dichroism (NIR-CD) characteristics of each coordination geometry in isolation. The spectra acquired support many of the conclusions and assumptions of previous studies and demonstrate that this spectroscopy is particularly sensitive to the distortion of the coordination polyhedron. This will have particularly relevant consequences when studying achiral YbDOTA-like systems forming labile adducts with (chiral) hosts and receptors.

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Solution Equilibria in YbDOTMA, a Chiral Analogue of One of the Most Successful Contrast Agents for MRI, GdDOTA

Cited by 40 publications

References 22 publications

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

Structure, Dynamics, and Computational Studies of Lanthanide‐Based Contrast Agents

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

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