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Martinelli J, Romano E, Laczovics A, Horváth D, Grattoni E, Baranyai Z, Tei L. Improving the Stability and Kinetic Inertness of Mn(II) Complexes by Increasing the Bridge Length in Bicyclic CDTA-Like Ligands. Chemistry 2024; 30:e202400570. [PMID: 38597334 DOI: 10.1002/chem.202400570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/11/2024]
Abstract
Kinetic inertness of Mn(II)-based MRI contrast agents can be improved by increasing the rigidity of the polydentate ligand that tightly coordinate the metal ion. Taking inspiration from the remarkable increase in kinetic inertness of [Mn(CDTA)]2- compared to [Mn(EDTA)]2- due to the cyclohexyl backbone rigidity, we devised that bicyclic ligands would further improve the kinetic inertness of the Mn(II) complexes. The length of the alkyl bridge on the cyclohexane ring was varied from methylene (BCH-DTA), ethylene (BCO-DTA) to propylene (BCN-DTA) to evaluate the influence of the different trans-diaminotetraacetate ligands on relaxometric, thermodynamic and kinetic properties of the Mn(II) complexes. 1H and 17O NMR relaxometric studies showed a slight increase in relaxivity and a faster water exchange rate in these Mn(II)-complexes with respect to [Mn(CDTA)]2-. Solution studies revealed that the conditional stability (pMn) and dissociation half-life (t1/2) at pH 7.4 follow the order [Mn(BCH-DTA)]2-<[Mn(BCO-DTA)]2-<[Mn(BCN-DTA)]2- highlighting the effect of the bridge length on the overall stability of the Mn(II) complexes. Remarkably, [Mn(BCN-DTA)]2- shows an improved pMn value and a 7-times higher kinetic inertness than [Mn(CDTA)]2-. NMR studies on the Zn(II) analogues confirm the rigidity of the bicyclic complexes with an isomerization process at >313 K for the smaller bridged complex [Zn(BCH-DTA)]2-.
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Affiliation(s)
- Jonathan Martinelli
- Department of Science and Technological Innovation, University of Piemonte Orientale, Viale Teresa Michel 11, 15121, Alessandria, Italy
- Department of Health Sciences (DISSAL), Università di Genova, Via A. Pastore 1, 16132, Genova, Italy
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genova, Italy
| | - Elisabetta Romano
- Department of Science and Technological Innovation, University of Piemonte Orientale, Viale Teresa Michel 11, 15121, Alessandria, Italy
| | - Attila Laczovics
- Faculty of Medicine, Institute of Medical Imaging, University of Debrecen, Nagyerdei körút 98, 4032, Debrecen, Hungary
| | - David Horváth
- Faculty of Science and Technology, Department of Physical Chemistry, Doctoral School of Chemistry, University of Debrecen, Egyetem tér 1, 4010, Debrecen, Hungary
- Bracco Imaging SpA, CRB Trieste, AREA Science Park, 34149, Basovizza (TS), Italy
| | - Elena Grattoni
- Bracco Imaging SpA, CRB Trieste, AREA Science Park, 34149, Basovizza (TS), Italy
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Piazzale Europa 1, 34127, Trieste (TS), Italy
| | - Zsolt Baranyai
- Bracco Imaging SpA, CRB Trieste, AREA Science Park, 34149, Basovizza (TS), Italy
- Faculty of Science and Technology, Doctoral School of Chemistry, University of Debrecen, Egyetem tér 1, 4010, Debrecen, Hungary
| | - Lorenzo Tei
- Department of Science and Technological Innovation, University of Piemonte Orientale, Viale Teresa Michel 11, 15121, Alessandria, Italy
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2
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Bunda S, Lihi N, Szaniszló Z, Esteban-Gómez D, Platas-Iglesias C, Kéri M, Papp G, Kálmán FK. Bipyridil-based chelators for Gd(III) complexation: kinetic, structural and relaxation properties. Dalton Trans 2023; 52:17030-17040. [PMID: 37937450 DOI: 10.1039/d3dt02806b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
In the last 20 years, research in the field of MRI (magnetic resonance imaging) contrast agents (CAs) has been intensified due to the emergence of a disease called nephrogenic systemic fibrosis (NSF). NSF has been linked to the in vivo dissociation of certain Gd(III)-based compounds applied in MRI as CAs. To prevent the dechelation of the probes after intravenous injection, the improvement of their in vivo stability is highly desired. The inertness of the Gd(III) chelates can be increased through the rigidification of the ligand structure. One of the potential ligands is (2,2',2'',2'''-(([2,2'-bipyridine]-6,6'-diylbis(methylene))bis(azanetriyl))tetraacetic acid) (H4DIPTA), which has been successfully used as a fluorescent probe for lanthanides; however, it has never been considered as a potential chelator for Gd(III) ions. In this paper, we report the thermodynamic, kinetic and structural features of the complex formed between Gd(III) and DIPTA. Since the solubility of the [Gd(DIPTA)]- chelate is very low under acidic conditions, hampering its thermodynamic characterization, we can only assume that its stability is close to that determined for the structural analogue [Gd(FENTA)]- (H4FENTA: (1,10-phenanthroline-2,9-diyl)bis(methyliminodiacetic acid)), which is similar to that determined for the agent [Gd(DTPA)]2- routinely used in clinical practice. Unfortunately, the inertness of [Gd(DIPTA)]- is significantly lower (t1/2 = 1.34 h) than that observed for [Gd(EGTA)]- and [Gd(DTPA)]2- as a result of its spontaneous dissociation pathway during dechelation. The relaxivity values of [Gd(DIPTA)]- are comparable with those of [Gd(FENTA)]- and somewhat higher than the values characterizing [Gd(DTPA)]2-. Luminescence lifetime measurements indicate the presence of one water molecule (q = 1) in the inner sphere of the complex with a relatively high water exchange rate (k298ex = 43(5) × 106 s-1). DFT calculations suggest a rigid distorted tricapped trigonal prismatic polyhedron for the Gd(III) complex. On the basis of these results, we can conclude that the bipyridine backbone is not favourable with respect to the inertness of the chelate.
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Affiliation(s)
- Szilvia Bunda
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
| | - Norbert Lihi
- HUN-REN-UD Mechanisms of Complex Homogeneous and Heterogeneous Chemical Reactions Research Group, Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Zsófia Szaniszló
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
| | - David Esteban-Gómez
- Centro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
| | - Carlos Platas-Iglesias
- Centro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
| | - Mónika Kéri
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
| | - Gábor Papp
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
| | - Ferenc Krisztián Kálmán
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
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3
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Luo Q, Liu J, Ma Q, Xu S, Wang L. Single-Atom Gd Nanoprobes for Self-Confirmative MRI with Robust Stability. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206821. [PMID: 36919250 DOI: 10.1002/smll.202206821] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 01/30/2023] [Indexed: 06/08/2023]
Abstract
Gadolinium (Gd)-based complexes are extensively utilized as contrast agents (CAs) in magnetic resonance imaging (MRI), yet, suffer from potential safety concerns and poor tumor targeting. Herein, as a mimic of Gd complex, single-atom Gd nanoprobes with r1 and r2 values of 34.2 and 80.1 mM-1 s-1 (far higher than that of commercial Gd CAs) at 3 T are constructed, which possessed T1 /T2 dual-mode MRI with excellent stability and good tumor targeting ability. Specifically, single-atom Gd is anchored on nitrogen-doped carbon matrix (Gd-Nx C) through spatial-confinement method, which is further subjected to controllable chemical etching to afford fully etched bowl-shape Gd-Nx C (feGd-Nx C) with hydrophilic properties and defined coordination structure, similar to commercial Gd complex. Such nanostructures not only maximized the Gd3+ site exposure, but also are suitable for self-confirmative diagnosis through one probe with dual-mode MRI. Moreover, the strong electron localization and interaction between Gd and N atoms afforded feGd-Nx C excellent kinetic inertness and thermal stability (no significant Gd3+ leaching is observed even incubated with Cu2+ and Zn2+ for two months), providing a creative design protocol for MRI CAs.
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Affiliation(s)
- Qing Luo
- State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Junhan Liu
- State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Qian Ma
- State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Suying Xu
- State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Leyu Wang
- State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
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4
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Lucio-Martínez F, Esteban-Gómez D, Valencia L, Horváth D, Szücs D, Fekete A, Szikra D, Tircsó G, Platas-Iglesias C. Rigid H 4OCTAPA derivatives as model chelators for the development of Bi(III)-based radiopharmaceuticals. Chem Commun (Camb) 2023; 59:3443-3446. [PMID: 36857648 DOI: 10.1039/d2cc06876a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Octadentate ligands containing ethyl (H4OCTAPA), cyclohexyl (H4CHXOCTAPA) or cyclopentyl (H4CpOCTAPA) spacers were assessed as chelators for Bi(III)-based radiopharmaceuticals. The H4CHXOCTAPA chelator displays excellent properties, including 205/206Bi-nuclide radiolabelling under mild conditions, excellent stability in serum and in the presence of competing cations or H5DTPA. The poor performance of H4CpOCTAPA appears to be related to the stereochemical activity of the Bi(III) lone pair.
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Affiliation(s)
- Fátima Lucio-Martínez
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - David Esteban-Gómez
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Laura Valencia
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidade de Vigo, As Lagoas, Marcosende, Pontevedra 36310, Spain
| | - Dávid Horváth
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary.
- Doctoral School of Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Dániel Szücs
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary.
- Doctoral School of Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98., Debrecen H-4032, Hungary.
| | - Anikó Fekete
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98., Debrecen H-4032, Hungary.
| | - Dezső Szikra
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98., Debrecen H-4032, Hungary.
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary.
| | - Carlos Platas-Iglesias
- 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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5
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Uzal-Varela R, Rodríguez-Rodríguez A, Wang H, Esteban-Gómez D, Brandariz I, Gale EM, Caravan P, Platas-Iglesias C. Prediction of Gd(III) complex thermodynamic stability. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214606] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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6
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Mallik R, Khannam M, Saha M, Marandi S, Kumar S, Mukherjee C. The electrostatic confinement of aquated monocationic Gd(III) complex-molecules within the inner core of porous silica nanoparticles creates a highly efficient T1 contrast agent for magnetic resonance imaging. Dalton Trans 2022; 51:14138-14149. [PMID: 36043989 DOI: 10.1039/d2dt02272a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Contrast-agent enhanced magnetic resonance imaging (MRI) has been under continuous investigation for the conspicuous imaging of lesions and the early-stage detection of tumors. To achieve the development of a T1-weighted contrast agent with a high relaxivity value, herein, porous silica nanoparticles that had internalized about 20 aquated cationic Gd(III) complexes (1) of the hexadentate hydroxyethyl-appended picolinate-based ligand H2hbda were demonstrated. Complex 1 exhibited a longitudinal relaxivity value per mM Gd(III) ions, r1, of 9.05 mM-1 s-1 (pH 7.4, 37 °C, 1.41 T), which increased to 86.41 mM-1 s-1 because of the grafting of complex 1 in the inner core of porous silica nanospheres through electrostatic interactions between the anionic silica surface and the cationic complex 1 molecules. A further augmentation in the relaxivity value to 118.32 mM-1 s-1 was realized because of the interaction of the complex 1@SiO2NPs with serum albumin protein. The synthesized nanosystem was impervious to physiologically available anions (HPO42- and HCO31-) and also kinetically inert, as evidenced via a transmetallation experiment in the presence of Zn(II) ions. The developed complex-incorporated nanomaterial was bio- and hemo-compatible. Cellular uptake measurements employing HeLa cells and the concentration-dependent enhancement in the brightness of in vitro phantom images, recorded under a clinical scanner at 1.5 T, demonstrated that the developed biocompatible 1@SiO2NP complex has promising diagnostic applications as a T1-weighted MRI contrast agent.
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Affiliation(s)
- Riya Mallik
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
| | - Mahmuda Khannam
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
| | - Muktashree Saha
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Shivani Marandi
- Centre for the Environment, Indian Institute of Technology Guwahati, Assam-781039, India
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Chandan Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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7
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Váradi B, Lihi N, Bunda S, Nagy A, Simon G, Kéri M, Papp G, Tircsó G, Esteban-Gómez D, Platas-Iglesias C, Kálmán FK. Physico-Chemical Characterization of a Highly Rigid Gd(III) Complex Formed with a Phenanthroline Derivative Ligand. Inorg Chem 2022; 61:13497-13509. [PMID: 35972786 DOI: 10.1021/acs.inorgchem.2c02050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The discovery of the nephrogenic systemic fibrosis (NSF) and its link with the in vivo dissociation of certain Gd(III)-based contrast agents (CAs) applied in the magnetic resonance imaging (MRI) induced a still growing research to replace the compromised agents with safer alternatives. In recent years, several ligands were designed to exploit the luminescence properties of the lanthanides, containing structurally constrained aromatic moieties, which may form rigid Gd(III) complexes. One of these ligands is (1,10-phenanthroline-2,9-diyl)bis(methyliminodiacetic acid) (H4FENTA) designed and synthesized to sensitize Eu(III) and Tb(III) luminescence. Our results show that the conditional stability of the [Gd(FENTA)]- chelate calculated for physiological pH (pGd = 19.7) is similar to those determined for [Gd(DTPA)]2- (pGd = 19.4) and [Gd(DOTA)]- (pGd = 20.1), routinely used in the clinical practice. The [Gd(FENTA)]- complex is remarkably inert with respect to its dissociation (t1/2 = 872 days at pH = 7 and 25 °C); furthermore, its relaxivity values determined at different field strengths and temperatures (e.g., r1p = 4.3 mM-1s-1at 60 MHz and 37 °C) are ca. one unit higher than those of [Gd(DTPA)]2- (r1p = 3.4 mM-1 s-1) and [Gd(DOTA)]- (r1p = 3.1 mM-1 s-1) under the same conditions. Moreover, significant improvement on the relaxivity was observed in the presence of serum proteins (r1p = 6.9 mM-1 s-1 at 60 MHz and 37 °C). The luminescence lifetimes recorded in H2O and D2O solutions indicate the presence of a water molecule (q = 1) in the inner sphere of the complex directly coordinated to the metal ion, possessing a relatively high water exchange rate (kex298 = 29(2) × 106 s-1). The acceleration of the water exchange can be explained by the steric compression around the water binding site due to the rigid structure of the complex, which was supported by DFT calculations. On the basis of these results, ligands containing a phenanthroline platform have great potential in the design of safer Gd(III) agents for MRI.
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Affiliation(s)
- Balázs Váradi
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary.,Doctoral School of Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Norbert Lihi
- ELKH-DE Mechanisms of Complex Homogeneous and Heterogeneous Chemical Reactions Research Group, Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Szilvia Bunda
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Antónia Nagy
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Gréta Simon
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Mónika Kéri
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Gábor Papp
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Univer-sidade da Coruña, A Coruña, Galicia 15071, Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Univer-sidade da Coruña, A Coruña, Galicia 15071, Spain
| | - Ferenc K Kálmán
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen H-4032, Hungary
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Piccinelli F, Sega D, Melchior A, Ruggieri S, Sanadar M, Varanini Z, Zamboni A. Regreening properties of the soil slow-mobile H 2bpcd/Fe 3+ complex: Steps forward to the development of a new environmentally friendly Fe fertilizer. FRONTIERS IN PLANT SCIENCE 2022; 13:964088. [PMID: 35991452 PMCID: PMC9386293 DOI: 10.3389/fpls.2022.964088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/14/2022] [Indexed: 06/01/2023]
Abstract
The application of synthetic Fe-chelates stands for the most established agronomical practice to alleviate lime-induced chlorosis, which still constitutes a major agronomic problem. However, the percolation through the soil profile due to the negative charge of the most deployed molecules results in agronomical and environmental problems. H2bpcd/Fe3+ complex features distinctive chemical characteristics, including moderate stability of the Fe(bpcd)+ species (logβ ML = 20.86) and a total positive charge, and we studied its behavior in soil and regreening effects on cucumber plants. Soil column experiments have underlined that H2bpcd/Fe3+ is retained in more amounts than EDDHA/Fe3+. The new ligand was not proven to be toxic for the cucumber and maize seedlings. A concentration of 20 μM H2bpcd/Fe3+ attained regreening of Fe-deficient cucumber plants grown in the hydroponic solution supplied with CaCO3, similar to that shown by EDDHA/Fe3+. Experiments with a 2 μM concentration of 57Fe showed that cucumber roots absorbed H2bpcd/57Fe3+ at a slower rate than EDTA/57Fe3+. The high kinetic inertness of H2bpcd/Fe3+ may explain such behavior.
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Affiliation(s)
- Fabio Piccinelli
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Davide Sega
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Andrea Melchior
- Dipartimento Politecnico di Ingegneria e Architettura, University of Udine, Udine, Italy
| | - Silvia Ruggieri
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Martina Sanadar
- Dipartimento Politecnico di Ingegneria e Architettura, University of Udine, Udine, Italy
| | - Zeno Varanini
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Anita Zamboni
- Department of Biotechnology, University of Verona, Verona, Italy
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9
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Lucio-Martínez F, Garda Z, Váradi B, Kálmán FK, Esteban-Gómez D, Tóth É, Tircsó G, Platas-Iglesias C. Rigidified Derivative of the Non-macrocyclic Ligand H 4OCTAPA for Stable Lanthanide(III) Complexation. Inorg Chem 2022; 61:5157-5171. [PMID: 35275621 PMCID: PMC8965877 DOI: 10.1021/acs.inorgchem.2c00501] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
The stability constants
of lanthanide complexes with the potentially
octadentate ligand CHXOCTAPA4–,
which contains a rigid 1,2-diaminocyclohexane scaffold functionalized
with two acetate and two picolinate pendant arms, reveal the formation
of stable complexes [log KLaL = 17.82(1)
and log KYbL = 19.65(1)]. Luminescence
studies on the Eu3+ and Tb3+ analogues evidenced
rather high emission quantum yields of 3.4 and 11%, respectively.
The emission lifetimes recorded in H2O and D2O solutions indicate the presence of a water molecule coordinated
to the metal ion. 1H nuclear magnetic relaxation dispersion
profiles and 17O NMR chemical shift and relaxation measurements
point to a rather low water exchange rate of the coordinated water
molecule (kex298 = 1.58 ×
106 s–1) and relatively high relaxivities
of 5.6 and 4.5 mM–1 s–1 at 20
MHz and 25 and 37 °C, respectively. Density functional theory
calculations and analysis of the paramagnetic shifts induced by Yb3+ indicate that the complexes adopt an unprecedented cis geometry
with the two picolinate groups situated on the same side of the coordination
sphere. Dissociation kinetics experiments were conducted by investigating
the exchange reactions of LuL occurring with Cu2+. The
results confirmed the beneficial effect of the rigid cyclohexyl group
on the inertness of the Lu3+ complex. Complex dissociation
occurs following proton- and metal-assisted pathways. The latter is
relatively efficient at neutral pH, thanks to the formation of a heterodinuclear
hydroxo complex. A
non-macrocyclic ligand containing a rigid cyclohexyl spacer
forms thermodynamically stable complexes with the lanthanide(III)
ions in aqueous solution. The complexes also show remarkable kinetic
inertness, though a structural change facilitates dissociation through
the metal-assisted mechanism for the small lanthanides. The Gd(III)
complex displays a relatively high relaxivity due to the presence
of a water molecule coordinated to the metal ion, while the Eu(III)
and Tb(III) analogues display strong metal-centered luminescence.
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Affiliation(s)
- Fátima Lucio-Martínez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
| | - Zoltán Garda
- Department of Physical Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary
| | - Balázs Váradi
- Department of Physical Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary.,Doctoral School of Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary
| | - Ferenc Krisztián Kálmán
- Department of Physical Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
| | - Éva Tóth
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d'Orléans, rue Charles Sadron, 45071 Orléans, Cedex 2, France
| | - Gyula Tircsó
- Department of Physical Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Galicia, Spain
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Piccinelli F, Nardon C, Bettinelli M, Melchior A, Tolazzi M, Zinna F, Di Bari L. Lanthanide‐Based Complexes Containing a Chiral
trans
‐1,2‐Diaminocyclohexane (DACH) Backbone: Spectroscopic Properties and Potential Applications. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Fabio Piccinelli
- Luminescent Materials Laboratory DB, University of Verona, and INSTM, UdR Verona Strada Le Grazie 15 37134 Verona Italy
| | - Chiara Nardon
- Luminescent Materials Laboratory DB, University of Verona, and INSTM, UdR Verona Strada Le Grazie 15 37134 Verona Italy
| | - Marco Bettinelli
- Luminescent Materials Laboratory DB, University of Verona, and INSTM, UdR Verona Strada Le Grazie 15 37134 Verona Italy
| | - Andrea Melchior
- Dipartimento Politecnico di ingegneria e architettura Laboratorio di Tecnologie Chimiche University of Udine Via Cotonificio 108 33100 Udine Italy
| | - Marilena Tolazzi
- Dipartimento Politecnico di ingegneria e architettura Laboratorio di Tecnologie Chimiche University of Udine Via Cotonificio 108 33100 Udine Italy
| | - Francesco Zinna
- Department of Chemistry and Industrial Chemistry Via Moruzzi 13 56124 Pisa Italy
| | - Lorenzo Di Bari
- Department of Chemistry and Industrial Chemistry Via Moruzzi 13 56124 Pisa Italy
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11
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Baranyai Z, Carniato F, Nucera A, Horváth D, Tei L, Platas-Iglesias C, Botta M. Defining the conditions for the development of the emerging class of Fe III-based MRI contrast agents. Chem Sci 2021; 12:11138-11145. [PMID: 34522311 PMCID: PMC8386674 DOI: 10.1039/d1sc02200h] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/07/2021] [Indexed: 02/05/2023] Open
Abstract
Fe(iii) complexes are attracting growing interest in chemists developing diagnostic probes for Magnetic Resonance Imaging because they leverage on an endogenous metal and show superior stability. However, in this case a detailed understanding of the relationship between the chemical structure of the complexes, their magnetic, thermodynamic, kinetic and redox properties and the molecular parameters governing the efficacy (relaxivity) is still far from being available. We have carried out an integrated 1H and 17O NMR relaxometric study as a function of temperature and magnetic field, on the aqua ion and three complexes chosen as reference models, together with theoretical calculations, to obtain accurate values of the parameters that control their relaxivity. Moreover, thermodynamic stability and dissociation kinetics of the Fe(iii) chelates, measured in association with the ascorbate reduction behaviour, highlight their role and mutual influence in achieving the stability required for use in vivo. An integrated 1H and 17O NMR relaxometric study on model systems allowed to highlight that the Fe(III) complexes might represent the best alternative to Gd-based MRI contrast agents at the magnetic fields of current and future clinical scanners.![]()
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Affiliation(s)
- Zsolt Baranyai
- Bracco Research Centre, Bracco Imaging S.p.A. Via Ribes 5 10010 Colleretto Giacosa Italy
| | - Fabio Carniato
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
| | - Alessandro Nucera
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
| | - Dávid Horváth
- Bracco Research Centre, Bracco Imaging S.p.A. Via Ribes 5 10010 Colleretto Giacosa Italy.,Department of Physical Chemistry, University of Debrecen Egyetem tér 1. H-4010 Debrecen Hungary
| | - 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), 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
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12
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Nizou G, Molnár E, Hamon N, Kálmán FK, Fougère O, Rousseaux O, Esteban-Gòmez D, Platas-Iglesias C, Beyler M, Tircsó G, Tripier R. Pyclen-Based Ligands Bearing Pendant Picolinate Arms for Gadolinium Complexation. Inorg Chem 2021; 60:2390-2405. [PMID: 33486958 DOI: 10.1021/acs.inorgchem.0c03277] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We report the synthesis of two pyclen-based regioisomer ligands (pyclen = 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene) functionalized with picolinic acid pendant arms either at positions 3,9-pc2pa (L5) or 3,6-pc2pa (L6) of the macrocyclic fragment. The ligands were prepared by the regiospecific protection of one of the amine nitrogen atoms of the macrocycle using Boc and Alloc protecting groups, respectively. The X-ray structure of the Gd(III) complex of L5 contains trinuclear [(GdL5)3(H2O)3]3+ entities in which the monomeric units are joined by μ2-η1:η1-carboxylate groups. However, the 1H and 89Y NMR spectra of its Y(III) analogue support the formation of monomeric complexes in solution. The Tb(III) complexes are highly luminescent, with emission quantum yields of up to 28% for [TbL5]+. The luminescence lifetimes recorded in H2O and D2O solutions indicate the presence of a water molecule coordinated to the metal ion, as also evidenced by the 1H relaxivities measured for the Gd(III) analogues. The Gd(III) complexes present very different exchange rates of the coordinated water molecule (kex298 = 87.1 × 106 and 1.06 × 106 s-1 for [GdL5]+ and [GdL6]+, respectively). The very high water exchange rate of [GdL5]+ is associated with the steric hindrance originating from the coordination of the ligand around the water binding site, which favors a dissociatively activated water exchange process. The Gd(III) complexes present rather high thermodynamic stabilities (log KGdL = 20.47 and 19.77 for [GdL5]+ and [GdL6]+, respectively). Furthermore, these complexes are remarkably inert with respect to their acid-assisted dissociation, in particular the complex of L5.
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Affiliation(s)
- Gwladys Nizou
- Univ. Brest, UMR-CNRS 6521 CEMCA, 6 avenue Victor le Gorgeu, 29238 Brest, France
| | - Enikő Molnár
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
| | - Nadège Hamon
- Univ. Brest, UMR-CNRS 6521 CEMCA, 6 avenue Victor le Gorgeu, 29238 Brest, France
| | - Ferenc Krisztián Kálmán
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
| | - Olivier Fougère
- Groupe Guerbet, Centre de Recherche d'Aulnay-sous-Bois, BP 57400, 95943 Roissy CdG Cedex, France
| | - Olivier Rousseaux
- Groupe Guerbet, Centre de Recherche d'Aulnay-sous-Bois, BP 57400, 95943 Roissy CdG Cedex, France
| | - David Esteban-Gòmez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Maryline Beyler
- Univ. Brest, UMR-CNRS 6521 CEMCA, 6 avenue Victor le Gorgeu, 29238 Brest, France
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
| | - Raphaël Tripier
- Univ. Brest, UMR-CNRS 6521 CEMCA, 6 avenue Victor le Gorgeu, 29238 Brest, France
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13
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Porcar-Tost O, Pallier A, Esteban-Gómez D, Illa O, Platas-Iglesias C, Tóth É, Ortuño RM. Stability, relaxometric and computational studies on Mn 2+ complexes with ligands containing a cyclobutane scaffold. Dalton Trans 2021; 50:1076-1085. [PMID: 33367361 DOI: 10.1039/d0dt03402a] [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
The stability constants of Mn2+ complexes with ligands containing a trans-1,2-cyclobutanediamine spacer functionalized with picolinate and/or carboxylate functions were determined using potentiometric titrations (25 °C, 0.1 M KCl). The stability constant of the complex with a hexadentate ligand containing four acetate groups (L14-, log KMnL = 10.26) is improved upon replacing one (L24-, log KMnL = 14.71) or two (L34-, log KMnL = 15.81) carboxylate groups with picolinates. The [Mn(L1)]2- complex contains a water molecule coordinated to the metal ion in aqueous solutions, as evidenced by 1H NMRD studies and 17O chemical shifts and transverse relaxation rates. The 1H relaxivities determined at 60 MHz (3.3 and 2.4 mM-1 s-1 at 25 and 37 °C, respectively) are comparable to those of monohydrated complexes such as [Mn(edta)]2-. The exchange rate of the inner-sphere water molecule (k = 248 × 106 s-1) is slightly lower than that of the edta4- analogue. DFT calculations (M11/def2-TZVP) suggest that the water exchange reaction follows a dissociatively activated mechanism, providing activation parameters in reasonably good agreement with the experimental data. DFT calculations also show that the 17O hyperfine coupling constant A/ℏ is affected slightly by changes in the Mn-Owater distance and the orientation of the water molecule with respect to the Mn-O vector.
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Affiliation(s)
- Oriol Porcar-Tost
- Departament de Química, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain.
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14
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Synthesis of a rigidified bicyclic AAZTA-like ligand and relaxometric characterization of its GdIII complex. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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15
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Johnston HM, Pota K, Barnett MM, Kinsinger O, Braden P, Schwartz TM, Hoffer E, Sadagopan N, Nguyen N, Yu Y, Gonzalez P, Tircsó G, Wu H, Akkaraju G, Chumley MJ, Green KN. Enhancement of the Antioxidant Activity and Neurotherapeutic Features through Pyridol Addition to Tetraazamacrocyclic Molecules. Inorg Chem 2019; 58:16771-16784. [PMID: 31774280 PMCID: PMC7323501 DOI: 10.1021/acs.inorgchem.9b02932] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's and other neurodegenerative diseases are chronic conditions affecting millions of individuals worldwide. Oxidative stress is a consistent component described in the development of many neurodegenerative diseases. Therefore, innovative strategies to develop drug candidates that overcome oxidative stress in the brain are needed. To target these challenges, a new, water-soluble 12-membered tetraaza macrocyclic pyridinophane L4 was designed and produced using a building-block approach. Potentiometric data show that the neutral species of L4 provides interesting zwitterionic behavior at physiological pH, akin to amino acids, and a nearly ideal isoelectric point of 7.3. The copper(II) complex of L4 was evaluated by X-ray diffraction and cyclic voltammetry to show the potential modes of antioxidant activity derived, which was also demonstrated by 2,2-diphenyl-1-picrylhydrazyl and coumarin carboxylic acid antioxidant assays. L4 was shown to have dramatically enhanced antioxidant activity and increased biological compatibility compared to parent molecules reported previously. L4 attenuated hydrogen peroxide (H2O2)-induced cell viability loss more efficiently than precursor molecules in the mouse hippocampal HT-22 cell model. L4 also showed potent (fM) level protection against H2O2 cell death in a BV2 microglial cell culture. Western blot studies indicated that L4 enhanced the cellular antioxidant defense capacity via Nrf2 signaling activation as well. Moreover, a low-cost analysis and high metabolic stability in phase I and II models were observed. These encouraging results show how the rational design of lead compounds is a suitable strategy for the development of treatments for neurodegenerative diseases where oxidative stress plays a substantial role.
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Affiliation(s)
- Hannah M. Johnston
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Kristof Pota
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Madalyn M. Barnett
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Olivia Kinsinger
- Department of Biology, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Paige Braden
- Department of Biology, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Timothy M. Schwartz
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Emily Hoffer
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Nishanth Sadagopan
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Nam Nguyen
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Yu Yu
- Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas (UNT) Health Science Center, Fort Worth, Texas 76107, United States
| | - Paulina Gonzalez
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Gyula Tircsó
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen H-4010, Hungary
| | - Hongli Wu
- Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas (UNT) Health Science Center, Fort Worth, Texas 76107, United States
- North Texas Eye Research Institute, University of North Texas (UNT) Health Science Center, Fort Worth, Texas 76107, United States
| | - Giridhar Akkaraju
- Department of Biology, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Michael J. Chumley
- Department of Biology, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Kayla N. Green
- Department of Chemistry and Biochemistry, Texas Christian University (TCU), 2950 S. Bowie, Fort Worth, Texas 76129, United States
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16
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Porcar-Tost O, Olivares JA, Pallier A, Esteban-Gómez D, Illa O, Platas-Iglesias C, Tóth É, Ortuño RM. Gadolinium Complexes of Highly Rigid, Open-Chain Ligands Containing a Cyclobutane Ring in the Backbone: Decreasing Ligand Denticity Might Enhance Kinetic Inertness. Inorg Chem 2019; 58:13170-13183. [PMID: 31524387 DOI: 10.1021/acs.inorgchem.9b02044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In an effort to explore novel ligand scaffolds for stable and inert lanthanide complexation in magnetic resonance imaging contrast agent research, three chiral ligands containing a highly rigid (1S,2S)-1,2-cyclobutanediamine spacer and different number of acetate and picolinate groups were efficiently synthesized. Potentiometric studies show comparable thermodynamic stability for the Gd3+ complexes formed with either the octadentate (L3)4- bearing two acetate or two picolinate groups or the heptadentate (L2)4- analogue bearing one picolinate and three acetate groups (log KGdL = 17.41 and 18.00 for [Gd(L2)]- and [Gd(L3)]-, respectively). In contrast, their dissociation kinetics is revealed to be very different: the monohydrated [Gd(L3)]- is considerably more labile, as a result of the significant kinetic activity of the protonated picolinate function, as compared to the bishydrated [Gd(L2)]-. This constitutes an uncommon example in which lowering ligand denticity results in a remarkable increase in kinetic inertness. Another interesting observation is that the rigid ligand backbone induces an unusually strong contribution of the spontaneous dissociation to the overall decomplexation process. Thanks to the presence of two inner-sphere water molecules, [Gd(L2)]- is endowed with high relaxivity (r1 = 7.9 mM-1 s-1 at 20 MHz, 25 °C), which is retained in the presence of large excess of endogenous anions, excluding ternary complex formation. The water exchange rate is similar for [Gd(L3)]- and [Gd(L2)]-, while it is 1 order of magnitude higher for the trishydrated tetraacetate analogue [Gd(L1)]- (kex298 = 8.1, 10, and 127 × 106 s-1, respectively). A structural analysis via density functional theory calculations suggests that the large bite angle imposed by the rigid (1S,2S)-1,2-cyclobutanediamine spacer could allow the design of ligands based on this scaffold with suitable properties for the coordination of larger metal ions with biomedical applications.
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Affiliation(s)
- Oriol Porcar-Tost
- Departament de Química , Universitat Autònoma de Barcelona , 08193 Cerdanyola del Vallès , Barcelona , Spain
| | - José A Olivares
- Departament de Química , Universitat Autònoma de Barcelona , 08193 Cerdanyola del Vallès , Barcelona , Spain
| | - Agnès Pallier
- Centre de Biophysique Moléculaire , UPR 4301, CNRS, Université d'Orléans , rue Charles Sadron , 45071 Orléans Cedex 2 , France
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas and Departamento de Química , Universidade da Coruña , Campus da Zapateira-Rúa da Fraga 10 , 15008 A Coruña , Spain
| | - Ona Illa
- Departament de Química , Universitat Autònoma de Barcelona , 08193 Cerdanyola del Vallès , Barcelona , Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas and Departamento de Química , Universidade da Coruña , Campus da Zapateira-Rúa da Fraga 10 , 15008 A Coruña , Spain
| | - Éva Tóth
- Centre de Biophysique Moléculaire , UPR 4301, CNRS, Université d'Orléans , rue Charles Sadron , 45071 Orléans Cedex 2 , France
| | - Rosa M Ortuño
- Departament de Química , Universitat Autònoma de Barcelona , 08193 Cerdanyola del Vallès , Barcelona , Spain
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17
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Green KN, Pota K, Tircsó G, Gogolák RA, Kinsinger O, Davda C, Blain K, Brewer SM, Gonzalez P, Johnston HM, Akkaraju G. Dialing in on pharmacological features for a therapeutic antioxidant small molecule. Dalton Trans 2019; 48:12430-12439. [PMID: 31342985 PMCID: PMC6863055 DOI: 10.1039/c9dt01800j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The pyridinophane molecule L2 (3,6,9,15-tetraazabicyclo[9.3.1]penta-deca-1(15),11,13-trien-13-ol) has shown promise as a therapuetic for neurodegenerative diseases involving oxidative stress and metal ion misregulation. Protonation and metal binding stability constants with Mg2+, Ca2+, Cu2+, and Zn2+ ions were determined to further explore the therapeutic and pharmacological potential of this water soluble small molecule. These studies show that incorporation of an -OH group in position 4 of the pyridine ring decreases the pI values compared to cyclen and L1 (3,6,9,15-tetraazabicyclo[9.3.1]penta-deca-1(15),11,13-triene). Furthermore, this approach tunes the basicity of the tetra-aza macrocyclic ligand through the enhanced resonance stabilization of the -OH in position 4 and rigidity of the pyridine ring such that L2 has increased basicity compared to previously reported tetra-aza macrocycles. A metal binding preference for Cu2+, a redox cycling agent known to produce oxidative stress, indicates that this would be the in vivo metal target of L2. However, the binding constant of L2 with Cu2+ is moderated compared to cyclen due to the rigidity of the ligand and shows how ligand design can be used to tune metal selectivity. An IC50 = 298.0 μM in HT-22 neuronal cells was observed. Low metabolic liability was determined in both Phase I and II in vitro models. Throughout these studies other metal binding systems were used for comparison and as appropriate controls. The reactivity reported to date and pharmacological features described herein warrant further studies in vivo and the pursuit of L2 congeners using the knowledge that pyridine substitution in a pyridinophane can be used to tune the structure of the ligand and retain the positive therapeutic outcomes.
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Affiliation(s)
- Kayla N Green
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Kristof Pota
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, H-4010, Hungary
| | - Réka Anna Gogolák
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, H-4010, Hungary
| | - Olivia Kinsinger
- Department of Biology, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA
| | - Collin Davda
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Kimberly Blain
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA. and Department of Biology, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA
| | - Samantha M Brewer
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Paulina Gonzalez
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Hannah M Johnston
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA.
| | - Giridhar Akkaraju
- Department of Biology, Texas Christian University, 2950 S. Bowie, Fort Worth, TX 76129, USA
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18
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Cyclobutane-Containing Scaffolds as Useful Intermediates in the Stereoselective Synthesis of Suitable Candidates for Biomedical Purposes: Surfactants, Gelators and Metal Cation Ligands. Int J Mol Sci 2019; 20:ijms20184333. [PMID: 31487921 PMCID: PMC6770955 DOI: 10.3390/ijms20184333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 08/28/2019] [Accepted: 09/02/2019] [Indexed: 11/16/2022] Open
Abstract
Efficient and versatile synthetic methodologies are reported for the preparation of products that are suitable candidates to be used as surfactants, gelators for hydroxylic solvents or metal cation ligands, with potential use in several fields including biomedical applications. The common structural feature of all the synthesized products is the presence of a cis or trans-1,2- or cis-1,3-difunctionalized cyclobutane ring. In the two first cases, the key intermediates including enantiomerically pure 1,3-diamines and 1,3-amino alcohols have been prepared from β-amino acid derivatives obtained, in turn, from a chiral half-ester. This compound is also precursor of γ-amino esters. Furthermore, two kind of polydentate ligands have also been synthesized from a symmetric 1,5-diamine obtained from norpinic acid, which was easily prepared from commercial verbenone.
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19
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Woods M, Payne KM, Valente EJ, Kucera BE, Young VG. Crystal Structures of DOTMA Chelates from Ce 3+ to Yb 3+ : Evidence for a Continuum of Metal Ion Hydration States. Chemistry 2019; 25:9997-10005. [PMID: 31121070 DOI: 10.1002/chem.201902068] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Indexed: 01/09/2023]
Abstract
The crystal structures of chelates formed between each stable paramagnetic lanthanide ion and the octadentate polyamino carboxylate ligand DOTMA are described. A total of 23 individual chelates structures were obtained; in each chelate the coordination geometry around the metal ion is best described as a twisted square antiprism (torsion angle -25.0°--31.4°). Despite the uniformity of the general coordination geometry provided by the DOTMA ligand, there is a considerable variation in the hydration state of each chelate. The early Ln3+ chelates are associated with a single inner sphere water molecule; the Ln-OH2 interaction is remarkable for being very long. After a clear break at gadolinium, the number of chelates in the unit cell that have a water molecule interacting with the Ln3+ decreases linearly until at Tm3+ no water is found to interact with the metal ion. The Ln-OH2 distance observed in the chelates of the later Ln3+ ions are also extremely long and increase as the ions contract (2.550-2.732 Å). No clear break between hydrated and dehydrated chelates is observed; rather this series of chelates appear to represent a continuum of hydration states in which the ligand gradually closes around the metal ion as its ionic radius decreases (with decreased hydration) and the metal drops down into the coordination cage.
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Affiliation(s)
- Mark Woods
- Advanced Imaging Research Center, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.,Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, OR, 97201, USA
| | - Katherine M Payne
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, OR, 97201, USA
| | - Edward J Valente
- Department of Chemistry, University of Portland, 5000 N. Willamette Boulevard, Portland, OR, 97203, USA
| | - Benjamin E Kucera
- Department of Chemistry, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, MN, 55455, USA
| | - Victor G Young
- Department of Chemistry, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, MN, 55455, USA
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20
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Clough TJ, Jiang L, Wong KL, Long NJ. Ligand design strategies to increase stability of gadolinium-based magnetic resonance imaging contrast agents. Nat Commun 2019; 10:1420. [PMID: 30926784 PMCID: PMC6441101 DOI: 10.1038/s41467-019-09342-3] [Citation(s) in RCA: 167] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 12/20/2018] [Indexed: 01/08/2023] Open
Abstract
Gadolinium(III) complexes have been widely utilised as magnetic resonance imaging (MRI) contrast agents for decades. In recent years however, concerns have developed about their toxicity, believed to derive from demetallation of the complexes in vivo, and the relatively large quantities of compound required for a successful scan. Recent efforts have sought to enhance the relaxivity of trivalent gadolinium complexes without sacrificing their stability. This review aims to examine the strategic design of ligands synthesised for this purpose, provide an overview of recent successes in gadolinium-based contrast agent development and assess the requirements for clinical translation.
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Affiliation(s)
- Thomas J Clough
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London, W12 0BZ, UK
| | - Lijun Jiang
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London, W12 0BZ, UK
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China
| | - Ka-Leung Wong
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China.
| | - Nicholas J Long
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London, W12 0BZ, UK.
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21
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Wahsner J, Gale EM, Rodríguez-Rodríguez A, Caravan P. Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers. Chem Rev 2019; 119:957-1057. [PMID: 30350585 PMCID: PMC6516866 DOI: 10.1021/acs.chemrev.8b00363] [Citation(s) in RCA: 832] [Impact Index Per Article: 166.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compounds, and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathological changes in the local environment. This comprehensive review describes the state of the art of clinically approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chemical exchange saturation transfer, and direct detection and the types of molecules that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathology either by direct biochemical targeting or by the design of responsive or activatable contrast agents.
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Affiliation(s)
- Jessica Wahsner
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Eric M. Gale
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Aurora Rodríguez-Rodríguez
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Peter Caravan
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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22
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Pujales-Paradela R, Carniato F, Uzal-Varela R, Brandariz I, Iglesias E, Platas-Iglesias C, Botta M, Esteban-Gómez D. A pentadentate member of the picolinate family for Mn(ii) complexation and an amphiphilic derivative. Dalton Trans 2019; 48:696-710. [PMID: 30547165 DOI: 10.1039/c8dt03856b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report a pentadentate ligand containing a 2,2'-azanediyldiacetic acid moiety functionalized with a picolinate group at the nitrogen atom (H3paada), as well as a lipophylic derivative functionalized with a dodecyloxy group at position 4 of the pyridyl ring (H3C12Opaada). The protonation constants of the paada3- ligand and the stability constant of the Mn(ii) complex were determined using a combination of potentiometric and spectrophotometric titrations (25 °C, 0.15 M NaCl). A detailed relaxometric characterisation was accomplished by recording 1H Nuclear Magnetic Relaxation Dispersion (NMRD) profiles and 17O chemical shifts and relaxation rates. These studies provide detailed information on the microscopic parameters that control their efficiency as relaxation agents in vitro. For the sake of completeness and to facilitate comparison, we also characterised the related [Mn(nta)]- complex (nta = nitrilotriacetate). Both the [Mn(paada)]- and [Mn(nta)]- complexes turned out to contain two inner-sphere water molecules in aqueous solution. The exchange rate of these coordinated water molecules was slower in [Mn(paada)]- (k298ex = 90 × 107 s-1) than in [Mn(nta)]- (k298ex = 280 × 107 s-1). The complexes were also characterised using both DFT (TPSSh/def2-TZVP) and ab initio CAS(5,5) calculations. The lipophylic [Mn(C12Opaada)]- complex forms micelles in solution characterised by a critical micellar concentration (cmc) of 0.31 ± 0.01 mM. This complex also forms a rather strong adduct with Bovine Serum Albumin (BSA) with an association constant of 5.5 × 104 M-1 at 25 °C. The enthalpy and entropy changes obtained for the formation of the adduct indicate that the binding event is driven by hydrophobic interactions.
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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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23
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Caneda-Martínez L, Valencia L, Fernández-Pérez I, Regueiro-Figueroa M, Angelovski G, Brandariz I, Esteban-Gómez D, Platas-Iglesias C. Toward inert paramagnetic Ni(ii)-based chemical exchange saturation transfer MRI agents. Dalton Trans 2018; 46:15095-15106. [PMID: 29067395 DOI: 10.1039/c7dt02758c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Ni2+ complexes with hexadentate ligands containing two 6-methylpicolinamide groups linked by ethane-1,2-diamine (dedpam) or cyclohexane-1,2-diamine (chxdedpam) spacers were investigated as potential contrast agents in magnetic resonance imaging (MRI). The properties of the complexes were compared to that of the analogues containing 6-methylpicolinate units (dedpa2- and chxdedpa2-). The X-ray structure of the [Ni(dedpam)]2+ complex reveals a six-coordinated metal ion with a distorted octahedral environment. The protonation constants of the dedpa2- and dedpam ligands and the stability constants of their Ni2+ complexes were determined using pH-potentiometry and spectrophotometric titrations (25 °C, 0.15 M NaCl). The [Ni(dedpa)] complex (log KNiL = 20.88(1)) was found to be considerably more stable than the corresponding amide derivative [Ni(dedpam)]2+ (log KNiL = 14.29(2)). However, the amide derivative [Ni(chxdedpam)]2+ was found to be considerably more inert with respect to proton-assisted dissociation than the carboxylate derivative [Ni(chxdedpa)]. A detailed 1H NMR and DFT study was conducted to assign the 1H NMR spectra of the [Ni(chxdedpa)] and [Ni(chxdedpam)]2+ complexes. The observed 1H NMR paramagnetic shifts were found to be dominated by the Fermi contact contribution. The amide resonances of [Ni(chxdedpam)]2+ at 91.5 and 22.2 ppm were found to provide a sizeable chemical exchange saturation transfer effect, paving the way for the development of NiCEST agents based on these rigid non-macrocyclic platforms.
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Affiliation(s)
- Laura Caneda-Martínez
- 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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24
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Burnett ME, Adebesin B, Ratnakar SJ, Green KN. Crystallographic Characterization and Non-Innocent Redox Activity of the Glycine Modified DOTA Scaffold and Its Impact on Eu III Electrochemistry. Eur J Inorg Chem 2018; 2018:1556-1562. [PMID: 30505213 PMCID: PMC6263031 DOI: 10.1002/ejic.201701398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 11/11/2022]
Abstract
EuDOTA-glycine derivatives have been explored as alternatives to typical gadolinium-containing complexes for MRI agents used in diagnostic imaging. Different imaging modalities can be accessed (T 1 or PARACEST) dependent on the oxidation state of the europium ion. Throughout the past 30 years, there have been significant manipulations and additions made to the DOTA scaffold; yet, characterizations related to electrochemistry and structure determined through XRD analysis have not been fully analyzed. In this work, electrochemical analysis using cyclic voltammetry was carried out on EuDOTA derivatives, including the free ligand DOTAGly4 (4) and the complexes. Effects of glycinate substitution on the DOTA scaffold, specifically, ligand interactions with the glassy carbon electrode were observed. A range of electrochemical investigations were carried out to show that increased glycinate substitution led to increased interaction with the electrode surface, thus implicating a new factor to consider when evaluating the electrochemistry of glycinate substituted ligands. In addition, the solid-state structure of EuDOTAGly4 (Eu4) was determined by X-ray diffraction and a brief analysis is presented compared to known Ln3+ structures found within literature. The Eu4 complex crystalizes in a rare polymer type arrangement via bridging side-arms between adjacent complexes.
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Affiliation(s)
- Marianne E Burnett
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 W. Bowie, Fort Worth, TX, 76129, USA, , http://chemistry.tcu.edu/staff/kayla-green/
| | - Bukola Adebesin
- Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75930, USA, , http://www.utsouthwestern.edu/education/medical-school/departments/airc/
| | - S James Ratnakar
- Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75930, USA, , http://www.utsouthwestern.edu/education/medical-school/departments/airc/
| | - Kayla N Green
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 W. Bowie, Fort Worth, TX, 76129, USA, , http://chemistry.tcu.edu/staff/kayla-green/
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25
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Nielsen LG, Junker AKR, Sørensen TJ. Composed in the f-block: solution structure and function of kinetically inert lanthanide(iii) complexes. Dalton Trans 2018; 47:10360-10376. [DOI: 10.1039/c8dt01501e] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
An induction to the wonders of lanthanides, and a call for standardised methods for characterisation of lanthanide complexes in solution.
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Affiliation(s)
- Lea Gundorff Nielsen
- Nano-Science Center & Department of Chemistry
- University of Copenhagen
- 2100 København Ø
- Denmark
| | - Anne Kathrine R. Junker
- Nano-Science Center & Department of Chemistry
- University of Copenhagen
- 2100 København Ø
- Denmark
| | - Thomas Just Sørensen
- Nano-Science Center & Department of Chemistry
- University of Copenhagen
- 2100 København Ø
- Denmark
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26
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Vanasschen C, Molnár E, Tircsó G, Kálmán FK, Tóth É, Brandt M, Coenen HH, Neumaier B. Novel CDTA-based, Bifunctional Chelators for Stable and Inert MnII Complexation: Synthesis and Physicochemical Characterization. Inorg Chem 2017. [DOI: 10.1021/acs.inorgchem.7b00460] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christian Vanasschen
- Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Enikő Molnár
- Department of Inorganic and Analytical Chemistry, Faculty
of Science and Technology, University of Debrecen, Debrecen, Egyetem tér 1, H-4010, Hungary
| | - Gyula Tircsó
- Department of Inorganic and Analytical Chemistry, Faculty
of Science and Technology, University of Debrecen, Debrecen, Egyetem tér 1, H-4010, Hungary
| | - Ferenc K. Kálmán
- Department of Inorganic and Analytical Chemistry, Faculty
of Science and Technology, University of Debrecen, Debrecen, Egyetem tér 1, H-4010, Hungary
- Centre de Biophysique Moléculaire,
CNRS, Université d’Orléans, rue Charles Sadron, 45071 Orléans, Cedex 2, France
- Le Studium, Loire Valley Institute for Advanced Studies, 1 Rue
Dupanloup, 45000 Orléans, France
| | - Éva Tóth
- Centre de Biophysique Moléculaire,
CNRS, Université d’Orléans, rue Charles Sadron, 45071 Orléans, Cedex 2, France
| | - Marie Brandt
- Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Heinz H. Coenen
- Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Bernd Neumaier
- Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Jülich, Germany
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27
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Leonzio M, Melchior A, Faura G, Tolazzi M, Zinna F, Di Bari L, Piccinelli F. Strongly Circularly Polarized Emission from Water-Soluble Eu(III)- and Tb(III)-Based Complexes: A Structural and Spectroscopic Study. Inorg Chem 2017; 56:4413-4422. [PMID: 28388073 DOI: 10.1021/acs.inorgchem.7b00430] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Water-soluble Eu(III) and Tb(III) complexes with N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetic acid (H2bpcd) have been synthesized and characterized in their racemic and enantiopure forms. The ligand has been designed to bind Ln(III) ions, providing a dissymmetric environment able to solicit strong chiroptical features while at the same time leaving a few coordination sites available for engaging further ancillary ligands. Potentiometric studies show that Ln(III) complexes have a relatively good stability and that at pH 7 the [Ln(bpcd)]+ species is largely dominant. DFT calculations carried out on the (S,S)-[Y(bpcd)(H2O)5]+ complexes (the closed-shell equivalents of [Eu(bpcd)(H2O)5]+ and [Tb(bpcd)(H2O)5]+) indicate that the two trans-O,O and trans-Npy,Npy configurations are equally stable in solution and present two coordinated water molecules. This is in agreement with the hydration number ∼2.6 determined by luminescence lifetime measurements on Tb(III) and Eu(III) complexes. A detailed optical and chiroptical spectroscopic characterization has been carried out and reveals that the complexes display an efficient luminescence in the visible spectral range accompanied by a strong CPL activity. A value for glum (around 0.1 on the top of the 546 nm band) for the Tb-based complex has been found. This is one of the highest glum values measured up to now for chiral Tb complexes. These results suggest that in principle Tb(bpcd)Cl is suitable to be employed as a CPL bioprobe for relevant analytes in aqueous media.
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Affiliation(s)
- Marco Leonzio
- Luminescent Materials Laboratory, DB, Università di Verona, and INSTM, UdR Verona , Strada Le Grazie 15, 37134 Verona, Italy
| | - Andrea Melchior
- Dipartimento Politecnico di Ingegneria e Architettura, Laboratorio di Tecnologie Chimiche, Università di Udine , via Cotonificio 108, 33100 Udine, Italy
| | - Georgina Faura
- Dipartimento Politecnico di Ingegneria e Architettura, Laboratorio di Tecnologie Chimiche, Università di Udine , via Cotonificio 108, 33100 Udine, Italy
| | - Marilena Tolazzi
- Dipartimento Politecnico di Ingegneria e Architettura, Laboratorio di Tecnologie Chimiche, Università di Udine , via Cotonificio 108, 33100 Udine, Italy
| | - Francesco Zinna
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa , via Moruzzi 13, 56124 Pisa, Italy
| | - Lorenzo Di Bari
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa , via Moruzzi 13, 56124 Pisa, Italy
| | - Fabio Piccinelli
- Luminescent Materials Laboratory, DB, Università di Verona, and INSTM, UdR Verona , Strada Le Grazie 15, 37134 Verona, Italy
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28
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Junker AKR, Tropiano M, Faulkner S, Sørensen TJ. Kinetically Inert Lanthanide Complexes as Reporter Groups for Binding of Potassium by 18-crown-6. Inorg Chem 2016; 55:12299-12308. [DOI: 10.1021/acs.inorgchem.6b02063] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Anne Kathrine R Junker
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Copenhagen, Denmark
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U. K
| | - Manuel Tropiano
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U. K
| | - Stephen Faulkner
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U. K
| | - Thomas Just Sørensen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Copenhagen, Denmark
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U. K
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