1
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Mysegaes F, Spiteller P, Bernarding J, Plaumann M. 19 F VT NMR: Novel Tm 3+ and Ce 3+ Complexes Provide New Insight into Temperature Measurement Using Molecular Sensors. Chemphyschem 2023; 24:e202300057. [PMID: 37384817 DOI: 10.1002/cphc.202300057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
In the past few decades, magnetic resonance spectroscopy (MRS) and MR imaging (MRI) have developed into a powerful non-invasive tool for medical diagnostic and therapy. Especially 19 F MR shows promising potential because of the properties of the fluorine atom and the negligible background signals in the MR spectra. The detection of temperature in a living organism is quite difficult, and usually external thermometers or fibers are used. Temperature determination via MRS needs temperature-sensitive contrast agents. This article reports first results of solvent and structural influences on the temperature sensitivity of 19 F NMR signals of chosen molecules. By using this chemical shift sensitivity, a local temperature can be determined with a high precision. Based on this preliminary study, we synthesized five metal complexes and compared the results of all variable temperature measurements. It is shown that the highest 19 F MR signal temperature dependence is detectable for a fluorine nucleus in a Tm3+ -complex.
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Affiliation(s)
- Felix Mysegaes
- University Bremen, Instrumental Analytics, Leobener Str. 7, 28359, Bremen, Germany
- Otto-von-Guericke University Magdeburg, Medical Faculty, Institute of Biometry and Medical Informatics, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Peter Spiteller
- University Bremen, Instrumental Analytics, Leobener Str. 7, 28359, Bremen, Germany
| | - Johannes Bernarding
- Otto-von-Guericke University Magdeburg, Medical Faculty, Institute of Biometry and Medical Informatics, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Markus Plaumann
- Otto-von-Guericke University Magdeburg, Medical Faculty, Institute of Biometry and Medical Informatics, Leipziger Str. 44, 39120, Magdeburg, Germany
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2
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Geng Y, Wu T, Han Q, Yang Y, Chen Z, Li X, Yin B, Zhou Y, Ling Y. Gadolinium-based contrast agents built of DO3A-pyridine scaffold: Precisely tuning carboxylate group for enhanced magnetic resonance imaging. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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3
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Martinelli J, Boccalon M, Horvath D, Esteban-Gomez D, Platas-Iglesias C, Baranyai Z, Tei L. The critical role of ligand topology: strikingly different properties of Gd( iii) complexes with regioisomeric AAZTA derivatives. Inorg Chem Front 2022. [DOI: 10.1039/d2qi00451h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Two regioisomeric Gd(III) complexes with heptadentate AAZTA-like ligands show different hydration state (q = 1 and 2) and astonishingly different thermodynamic stability and dissociation kinetics.
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Affiliation(s)
- Jonathan Martinelli
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “A. Avogadro”, Viale T. Michel 11, 15121 Alessandria, Italy
| | - Mariangela Boccalon
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010, Colleretto Giacosa, Italy
| | - David Horvath
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010, Colleretto Giacosa, Italy
- University of Debrecen, Faculty of Science and Technology, Department of Physical Chemistry, Doctoral School of Chemistry, Debrecen, Hungary
| | - David Esteban-Gomez
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain
| | - Carlos Platas-Iglesias
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain
| | - Zsolt Baranyai
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010, Colleretto Giacosa, Italy
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “A. Avogadro”, Viale T. Michel 11, 15121 Alessandria, Italy
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4
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Lalli D, Carniato F, Tei L, Platas-Iglesias C, Botta M. Surprising Complexity of the [Gd(AAZTA)(H 2O) 2] - Chelate Revealed by NMR in the Frequency and Time Domains. Inorg Chem 2021; 61:496-506. [PMID: 34890182 PMCID: PMC8753608 DOI: 10.1021/acs.inorgchem.1c03194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
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Typically, Ln(III)
complexes are isostructural along the series,
which enables studying one particular metal chelate to derive the
structural features of the others. This is not the case for [Ln(AAZTA)(H2O)x]− (x = 1, 2) systems, where structural variations along the
series cause changes in the hydration number of the different metal
complexes, and in particular the loss of one of the two metal-coordinated
water molecules between Ho and Er. Herein, we present a 1H field-cycling relaxometry and 17O NMR study that enables
accessing the different exchange dynamics processes involving the
two water molecules bound to the metal center in the [Gd(AAZTA)(H2O)2]− complex. The resulting
picture shows one Gd-bound water molecule with an exchange rate ∼6
times faster than that of the other, due to a longer metal–water
distance, in accordance with density functional theory (DFT) calculations.
The substitution of the more labile water molecule with a fluoride
anion in a diamagnetic-isostructural analogue of the Gd-complex, [Y(AAZTA)(H2O)2]−, allows us to follow the
chemical exchange process by high-resolution NMR and to describe its
thermodynamic behavior. Taken together, the variety of tools offered
by NMR (including high-resolution 1H, 19F NMR
as a function of temperature, 1H longitudinal relaxation
rates vs B0, and 17O transverse
relaxation rates vs T) provides a complete description
of the structure and exchange dynamics of these Ln-complexes along
the series. Herein, we present a 1H field−cycling
relaxometry and 17O NMR study that enables accessing the
different exchange dynamics processes involving the two water molecules
bound to the metal center in the [Gd(AAZTA)(H2O)2]− complex.
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Affiliation(s)
- Daniela Lalli
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
| | - Fabio Carniato
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
| | - Mauro Botta
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy.,Magnetic Resonance Platform (PRISMA-UPO), Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
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5
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Boccalon M, Leone L, Marino G, Demitri N, Baranyai Z, Tei L. Underlining the Importance of Peripheral Protic Functional Groups to Enhance the Proton Exchange of Gd-Based MRI Contrast Agents. Inorg Chem 2021; 60:13626-13636. [PMID: 34387463 PMCID: PMC8769378 DOI: 10.1021/acs.inorgchem.1c01927] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
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In
this study, we report the synthesis and the equilibrium, kinetic,
relaxation, and structural properties of two new GdIII complexes
based on modified 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic
acid (HPDO3A) designed to modulate the relaxivity at acidic and basic
pH due to intra- and intermolecular proton exchange. The presence
of a carboxylic or ester moieties in place of the methyl group of
HPDO3A allowed differentiation of a protic and nonprotic functional
group, highlighting the importance of the formation of an intramolecular
hydrogen bond between the coordinated hydroxyl and the carboxylate
groups for proton exchange (kH = 1.5 ×
1011 M–1 s–1, kOH = 1.7 × 109 M–1 s–1). The determination of the thermodynamic stability
and kinetic inertness of the GdIII complexes confirmed
that the modification of peripheral groups does not significantly
affect the coordination environment and thus the stability (log KGdL = 19.26, t1/2 = 2.14 × 107 hours, pH = 7.4, 0.15 M NaCl, 25 °C).
The relaxivity (r1) was measured as a
function of pH to investigate the proton exchange kinetics, and as
a function of the magnetic field strength to extrapolate the relaxometric
parameters (r1GdL1 = 4.7 mM–1 s–1 and r1GdL2 = 5.1 mM–1 s–1 at 20 MHz, 25 °C, and pH 7.4). Finally, the X-ray crystal structure
of the complex crystallized at basic pH showed the formation of a
tetranuclear dimer with alkoxide and hydroxide groups bridging the
GdIII ions. The peripheral
carboxylic moiety of a 2-hydroxypropanoic
pendant arm of a GdHPDO3A-like complex forms an intramolecular hydrogen
bond with the −OH group that allows both acid- and base-catalyzed
proton exchange and thus a relaxivity enhancement. Conversely, the
nonprotic ester group in the same position permits only the base-catalyzed
mechanism.
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Affiliation(s)
- Mariangela Boccalon
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010 Colleretto Giacosa, Italy
| | - Loredana Leone
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
| | - Giuseppe Marino
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010 Colleretto Giacosa, Italy
| | - Nicola Demitri
- Elettra-Sincrotrone Trieste, S.S. 14 Km 163.5 in Area Science Park, Basovizza, 34149 Trieste, Italy
| | - Zsolt Baranyai
- Bracco Research Centre, Bracco Imaging S.p.A., Via Ribes 5, 10010 Colleretto Giacosa, Italy
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy
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6
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Asik D, Abozeid SM, Turowski SG, Spernyak JA, Morrow JR. Dinuclear Fe(III) Hydroxypropyl-Appended Macrocyclic Complexes as MRI Probes. Inorg Chem 2021; 60:8651-8664. [PMID: 34110140 PMCID: PMC9942924 DOI: 10.1021/acs.inorgchem.1c00634] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Four high-spin Fe(III) macrocyclic complexes, including three dinuclear and one mononuclear complex, were prepared toward the development of more effective iron-based magnetic resonance imaging (MRI) contrast agents. All four complexes contain a 1,4,7-triazacyclononane macrocyclic backbone with two hydroxypropyl pendant groups, an ancillary aryl or biphenyl group, and a coordination site for a water ligand. The pH potentiometric titrations support one or two deprotonations of the complexes, most likely deprotonation of hydroxypropyl groups at near-neutral pH. Variable-temperature 17O NMR studies suggest that the inner-sphere water ligand is slow to exchange with bulk water on the NMR time scale. Water proton T1 relaxation times measured for solutions of the Fe(III) complexes at pH 7.2 showed that the dinuclear complexes have a 2- to 3-fold increase in r1 relaxivity in comparison to the mononuclear complex per molecule at field strengths ranging from 1.4 T to 9.4 T. The most effective agent, a dinuclear complex with macrocycles linked through para-substitution of an aryl group (Fe2(PARA)), has an r1 of 6.7 mM-1 s-1 at 37 °C and 4.7 T or 3.3 mM-1 s-1 per iron center in the presence of serum albumin and shows enhanced blood pool and kidney contrast in mice MRI studies.
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Affiliation(s)
- Didar Asik
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Samira M. Abozeid
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Steven G. Turowski
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, New York 14263 United States
| | - Joseph A. Spernyak
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, New York 14263 United States
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
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7
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Baroni S, Carnovale IM, Carrera C, Boccalon M, Guidolin N, Demitri N, Lattuada L, Tedoldi F, Baranyai Z, Aime S. H-Bonding and intramolecular catalysis of proton exchange affect the CEST properties of Eu III complexes with HP-DO3A-like ligands. Chem Commun (Camb) 2021; 57:3287-3290. [PMID: 33656033 DOI: 10.1039/d1cc00366f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Eu(HP-DO3A) is present in solution as a mixture of two diastereoisomers whose alcoholic groups are the source of the mobile protons for the CEST effect. The exchange is base catalyzed. Two novel EuIII complexes of HP-DO3A-like ligands containing an amino or a carboxylate functionality in the proximity of the -OH groups showed the occurrence of intramolecular catalysis of the prototropic exchange. New insights into the role of the intramolecular proton exchange on the CEST properties have been gained.
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Affiliation(s)
- Simona Baroni
- Department of Molecular Biotechnologies and Health Sciences, Molecular Imaging Center, University of Torino, Via Nizza 52, 10126 Torino, Italy.
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8
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Leone L, Camorali S, Freire-García A, Platas-Iglesias C, Esteban Gomez D, Tei L. Scrutinising the role of intramolecular hydrogen bonding in water exchange dynamics of Gd(iii) complexes. Dalton Trans 2021; 50:5506-5518. [DOI: 10.1039/d1dt00204j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The water exchange rate in GdIII-complexes bearing substituted acetophenone moieties is modulated by the ability of peripherical substituents to establish hydrogen bonds with the coordinated and/or second sphere water molecules.
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Affiliation(s)
- Loredana Leone
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT). Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- I-15121 Alessandria
- Italy
| | - Sara Camorali
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT). Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- I-15121 Alessandria
- Italy
| | - Antía Freire-García
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Facultade de Ciencias
- Universidade da Coruña
- 15071 A Coruña
- Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Facultade de Ciencias
- Universidade da Coruña
- 15071 A Coruña
- Spain
| | - David Esteban Gomez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Facultade de Ciencias
- Universidade da Coruña
- 15071 A Coruña
- Spain
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT). Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- I-15121 Alessandria
- Italy
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9
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Leone L, Boccalon M, Ferrauto G, Fábián I, Baranyai Z, Tei L. Acid-catalyzed proton exchange as a novel approach for relaxivity enhancement in Gd-HPDO3A-like complexes. Chem Sci 2020; 11:7829-7835. [PMID: 34123071 PMCID: PMC8163333 DOI: 10.1039/d0sc02174a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A current challenge in medical diagnostics is how to obtain high MRI relaxation enhancement using GdIII-based contrast agents (CAs) containing the minimum concentration of GdIII ions. We report that in GdHPDO3A-like complexes a primary amide group located in close proximity to the coordinated hydroxyl group can provide a strong relaxivity enhancement at slightly acidic pH. A maximum relaxivity of r1 = 9.8 mM−1 s−1 (20 MHz, 298 K) at acidic pH was achieved, which is more than double that of clinically approved MRI contrast agents under identical conditions. This effect was found to strongly depend on the number of amide protons, i.e. it decreases with a secondary amide group and almost completely vanishes with a tertiary amide. This relaxivity enhancement is attributed to an acid-catalyzed proton exchange process between the metal-coordinated OH group, the amide protons and second sphere water molecules. The mechanism and kinetics of the corresponding H+ assisted exchange process are discussed in detail and a novel simultaneous double-site proton exchange mechanism is proposed. Furthermore, 1H and 17O NMR relaxometry, Chemical Exchange Saturation Transfer (CEST) on the corresponding EuIII complexes, and thermodynamic and kinetic studies are reported. These highlight the optimal physico-chemical properties required to achieve high relaxivity with this series of GdIII-complexes. Thus, proton exchange provides an important opportunity to enhance the relaxivity of contrast agents, providing that labile protons close to the paramagnetic center can contribute. A novel GdHPDO3A-like complex featuring primary amide side chain induces extraordinary high relaxivity by virtue of a simultaneous double-site proton exchange mechanism under slight acidic conditions.![]()
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Affiliation(s)
- Loredana Leone
- Department of Science and Technological Innovation, Università del Piemonte Orientale Viale T. Michel 11 15121 Alessandria Italy
| | - Mariangela Boccalon
- Bracco Imaging SpA, Bracco Research Center Via Ribes 5 10010 Colleretto Giacosa TO Italy
| | - Giuseppe Ferrauto
- Department of Molecular Biotechnology and Health Science, University of Turin Via Nizza 52 10126 Torino Italy
| | - István Fábián
- Department of Inorganic and Analytical Chemistry, MTA-DE Redox and Homogeneous Catalytic Reaction Mechanisms Research Group, University of Debrecen Egyetem tér 1. H-4032 Debrecen Hungary
| | - Zsolt Baranyai
- Bracco Imaging SpA, Bracco Research Center Via Ribes 5 10010 Colleretto Giacosa TO Italy
| | - Lorenzo Tei
- Department of Science and Technological Innovation, Università del Piemonte Orientale Viale T. Michel 11 15121 Alessandria Italy
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10
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Tear LR, Carrera C, Gianolio E, Aime S. Towards an Improved Design of MRI Contrast Agents: Synthesis and Relaxometric Characterisation of Gd-HPDO3A Analogues. Chemistry 2020; 26:6056-6063. [PMID: 32133687 DOI: 10.1002/chem.202000479] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/02/2020] [Indexed: 11/10/2022]
Abstract
The properties of LnIII -HPDO3A complexes as relaxation enhancers and paraCEST agents are essentially related to the hydroxylpropyl moiety. A series of three HPDO3A derivatives, with small modifications to the hydroxyl arm, were herein investigated to understand how heightened control can be gained over the parameters involved in the design of these agents. A full 1 H and 17 O-NMR relaxometric analysis was conducted and demonstrated that increasing the length of the OH group from the lanthanide centre significantly enhanced the water exchange rate of the gadolinium complex, but with a subsequent reduction in kinetic stability. Alternatively, the introduction of an additional methyl group, which increased the steric bulk around the OH moiety, resulted in the formation of almost exclusively the TSAP isomer (95 %) as identified by 1 H-NMR of the europium complex. The gadolinium analogue of this complex also exhibited a very fast water exchange rate, but with no detectable loss of kinetic stability. This complex therefore demonstrates a notable improvement over Gd-HPDO3A.
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Affiliation(s)
- Louise R Tear
- Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Centre, University of Torino, Via Nizza 52, 10126, Torino, Italy
| | - Carla Carrera
- Institute of Biostructures and Bioimaging, National Research Council, Via Nizza 52, 10126, Torino, Italy
| | - Eliana Gianolio
- Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Centre, University of Torino, Via Nizza 52, 10126, Torino, Italy
| | - Silvio Aime
- Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Centre, University of Torino, Via Nizza 52, 10126, Torino, Italy
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11
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Pujales-Paradela R, Carniato F, Esteban-Gómez D, Botta M, Platas-Iglesias C. Controlling water exchange rates in potential Mn 2+-based MRI agents derived from NO2A 2. Dalton Trans 2019; 48:3962-3972. [PMID: 30834411 DOI: 10.1039/c9dt00211a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We report a series of pentadentate ligands based on a 1,4,7-triazacyclononane-1,4-diacetic acid (H2NO2A) containing different substituents attached to the third nitrogen atom of the macrocyclic unit. Detailed 1H Nuclear Magnetic Relaxation Dispersion (NMRD) characterisation of the corresponding Mn2+ complexes suggests the formation of six-coordinate species in solution containing an inner-sphere water molecule. This was confirmed by recording the transverse 17O relaxation time and chemical shift measurements. The water exchange rate of the coordinated water molecule was found to be strongly influenced by the nature of the substituent R at position 7 of the triazacyclononane unit (R = Me, k298ex = 62.6 × 107 s-1; R = Bz, k298ex = 4.4 × 107 s-1; R = 1-phenylethyl, k298ex = 2.6 × 107 s-1). The decreasing exchange rates are explained by the increasing bulkiness of the substituent, which hinders the approach of the entering water molecule in an associatively activated water exchange mechanism. This is supported by DFT calculations (M062X/TZVP), which confirm the associative nature of the water exchange reaction. A potentially decadentate ligand containing two NO2A units linked by a xylenyl spacer in the meta position was also synthesised. The corresponding binuclear Mn2+ complex contains two metal ions with different hydration numbers, as evidenced by 1H NMRD and 17O NMR measurements. DFT calculations show that this is related to the presence of a bridging bidentate μ-η1-carboxylate group connecting the two metal centers. The results reported in this work provide a straightforward strategy to control the exchange rate of the coordinated water molecule in this family of MRI contrast agent candidates.
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Affiliation(s)
- Rosa Pujales-Paradela
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
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12
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Caravan P, Esteban-Gómez D, Rodríguez-Rodríguez A, Platas-Iglesias C. Water exchange in lanthanide complexes for MRI applications. Lessons learned over the last 25 years. Dalton Trans 2019; 48:11161-11180. [DOI: 10.1039/c9dt01948k] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Coordination chemistry offers convenient strategies to modulate the exchange of coordinated water molecules in lanthanide-based contrast agents.
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Affiliation(s)
- Peter Caravan
- The Institute for Innovation in Imaging and the A. A. Martinos Center for Biomedical Imaging
- Massachusetts General Hospital
- Harvard Medical School
- Charlestown
- USA
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Universidade da Coruña
- 15008 A Coruña
- Spain
| | - Aurora Rodríguez-Rodríguez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Universidade da Coruña
- 15008 A Coruña
- Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Universidade da Coruña
- 15008 A Coruña
- Spain
- The Institute for Innovation in Imaging and the A. A. Martinos Center for Biomedical Imaging
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