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Pérez-Lourido P, Madarasi E, Antal F, Esteban-Gómez D, Wang G, Angelovski G, Platas-Iglesias C, Tircsó G, Valencia L. Stable and inert macrocyclic cobalt(II) and nickel(II) complexes with paraCEST response. Dalton Trans 2022; 51:1580-1593. [PMID: 34991150 DOI: 10.1039/d1dt03217h] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We report the synthesis of the macrocyclic ligands 3,9-PC2AMH (2,2'-(3,6,9-triaza-1(2,6)-pyridinacyclodecaphane-3,9-diyl)diacetamide) and 3,9-PC2AMtBu (2,2'-(3,6,9-triaza-1(2,6)-pyridinacyclodecaphane-3,9-diyl)bis(N-tert-butyl)acetamide) which contain a pyclen platform functionalized with acetamide or tert-butylacetamide pendant arms at positions 3 and 9 of the macrocyclic unit. The corresponding Co(II) and Ni(II) complexes were prepared, isolated and characterised as potential paramagnetic chemical exchange saturation transfer (paraCEST) agents. The X-ray structures of the Ni(II) complexes reveal six-coordination of the ligands to the metal ion. The Co(II) complex with 3,9-PC2AMtBu shows a similar six-coordinate structure in the solid state, while the Co(II) complex with 3,9-PC2AMH contains a seven-coordinate metal ion, seventh coordination being completed by the presence of an inner-sphere water molecule. The structure of the Co(II) complexes was investigated using 1H NMR spectroscopy and computational methods. The complexes present a seven-coordinate structure in solution, as demonstrated by the analysis of the paramagnetic shifts using density functional theory. Ligand protonation constants and stability constants of the complexes with 3,9-PC2AMH were determined using potentiometric titrations (I = 0,15 M NaCl). The Co(II) complex was found to be more stable than the Ni(II) analogue (log KCoL = 14.46(5) and log KNiL = 13.15(3)). However, the Ni(II) and Co(II) complexes display similar rate constants characterizing the proton-assisted dissociation mechanism. The presence of highly shifted 1H NMR signals due to the amide protons in slow exchange with bulk water results in sizeable CEST signals, which are observed at +67 and +15 ppm for the Co(II) complex with 3,9-PC2AMH and +42 and +7 ppm for the Ni(II) analogue at 25 °C.
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Affiliation(s)
- Paulo Pérez-Lourido
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidade de Vigo, As Lagoas, Marcosende, 36310 Pontevedra, Spain.
| | - Enikő Madarasi
- Doctoral School of Chemistry, Faculty of Science and Technology, University of Debrecen, H-4010, Debrecen, Egyetem tér 1, Hungary
| | - Fanni Antal
- Doctoral School of Chemistry, Faculty of Science and Technology, University of Debrecen, H-4010, Debrecen, Egyetem tér 1, Hungary
| | - David Esteban-Gómez
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Gaoji Wang
- MR Neuroimaging Agents, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Goran Angelovski
- MR Neuroimaging Agents, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany.,Laboratory of Molecular and Cellular Neuroimaging, International Center for Primate Brain Research (ICPBR), Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences (CAS), 20031 Shanghai, PR China
| | - Carlos Platas-Iglesias
- Universidade da Coruña, Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4010, Debrecen, Egyetem tér 1, Hungary
| | - Laura Valencia
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidade de Vigo, As Lagoas, Marcosende, 36310 Pontevedra, Spain.
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Tóth-Molnár E, Lihi N, Gál GT, De S, Bombicz P, Bányai I, Szikra D, Dénes E, Tircsó G, Tóth I, Kálmán FK. Exploring Cyclic Aminopolycarboxylate Ligands for Sb(III) Complexation: PCTA and Its Derivatives as a Promising Solution. Inorg Chem 2021; 60:14253-14262. [PMID: 34463492 DOI: 10.1021/acs.inorgchem.1c01765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In recent years Auger electron emitters have been suggested as promising candidates for radiotherapy with no side effects in cancer treatment. In this work we report a detailed coordination chemistry study of [Sb(PCTA)] (PCTA: 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid), a macrocyclic aminopolycarboxylate-type complex of antimony(III), whose 119Sb isotope could be a suitable low-energy electron emitter for radiotherapy. The thermodynamic stability of the chelate obtained by pH-potentiometry and UV-vis spectrophotometry is high enough (log K[Sb(PCTA)] = 23.2(1)) to prevent the hydrolysis of the metal ion near physiological pH. The formation of [Sb(PCTA)] is confirmed by NMR and electrospray ionization mass spectrometry measurements in solution; furthermore, the structure of [Sb(PCTA)]·NaCl·3H2O and [Sb(PCTA)]·HCl·3H2O is described by X-ray and density functional theory calculations. Consequently, the [Sb(PCTA)] is the first thermodynamically stable antimony(III) complex bearing polyamino-polycarboxylate macrocyclic platform. Our results demonstrate the potential of rigid (pyclen derivative) ligands as chelators for future applications of Sb(III) in a targeted radiotherapy based on the 119Sb isotope.
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Affiliation(s)
- Enikő Tóth-Molnár
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Norbert Lihi
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Gyula Tamás Gál
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Sourav De
- Research Laboratory of Chemical Crystallography, Research Centre for Natural Sciences, H-1117 Budapest, Hungary
| | - Petra Bombicz
- Research Laboratory of Chemical Crystallography, Research Centre for Natural Sciences, H-1117 Budapest, Hungary
| | - István Bányai
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Dezső Szikra
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, University of Debrecen, H-4032 Debrecen, Hungary
| | - Eleonóra Dénes
- Centre of Supramolecular Organic and Organometallic Chemistry, Department of Chemistry, Babeş-Bolyai University, RO-400028 Cluj-Napoca, Romania
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Imre Tóth
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.,Department of Inorganic and Analytical 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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Kálmán FK, Nagy V, Uzal-Varela R, Pérez-Lourido P, Esteban-Gómez D, Garda Z, Pota K, Mezei R, Pallier A, Tóth É, Platas-Iglesias C, Tircsó G. Expanding the Ligand Classes Used for Mn(II) Complexation: Oxa-aza Macrocycles Make the Difference. Molecules 2021; 26:molecules26061524. [PMID: 33802241 PMCID: PMC7998310 DOI: 10.3390/molecules26061524] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 02/27/2021] [Accepted: 02/28/2021] [Indexed: 12/16/2022] Open
Abstract
We report two macrocyclic ligands based on a 1,7-diaza-12-crown-4 platform functionalized with acetate (tO2DO2A2−) or piperidineacetamide (tO2DO2AMPip) pendant arms and a detailed characterization of the corresponding Mn(II) complexes. The X−ray structure of [Mn(tO2DO2A)(H2O)]·2H2O shows that the metal ion is coordinated by six donor atoms of the macrocyclic ligand and one water molecule, to result in seven-coordination. The Cu(II) analogue presents a distorted octahedral coordination environment. The protonation constants of the ligands and the stability constants of the complexes formed with Mn(II) and other biologically relevant metal ions (Mg(II), Ca(II), Cu(II) and Zn(II)) were determined using potentiometric titrations (I = 0.15 M NaCl, T = 25 °C). The conditional stabilities of Mn(II) complexes at pH 7.4 are comparable to those reported for the cyclen-based tDO2A2− ligand. The dissociation of the Mn(II) chelates were investigated by evaluating the rate constants of metal exchange reactions with Cu(II) under acidic conditions (I = 0.15 M NaCl, T = 25 °C). Dissociation of the [Mn(tO2DO2A)(H2O)] complex occurs through both proton− and metal−assisted pathways, while the [Mn(tO2DO2AMPip)(H2O)] analogue dissociates through spontaneous and proton-assisted mechanisms. The Mn(II) complex of tO2DO2A2− is remarkably inert with respect to its dissociation, while the amide analogue is significantly more labile. The presence of a water molecule coordinated to Mn(II) imparts relatively high relaxivities to the complexes. The parameters determining this key property were investigated using 17O NMR (Nuclear Magnetic Resonance) transverse relaxation rates and 1H nuclear magnetic relaxation dispersion (NMRD) profiles.
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Affiliation(s)
- Ferenc K. Kálmán
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary; (F.K.K.); (V.N.); (Z.G.); (R.M.)
| | - Viktória Nagy
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary; (F.K.K.); (V.N.); (Z.G.); (R.M.)
| | - Rocío Uzal-Varela
- Centro de Investigacións Científicas Avanzadas (CICA), Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Spain; (R.U.-V.); (D.E.-G.)
| | - Paulo Pérez-Lourido
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidade de Vigo, As Lagoas, Marcosende, 36310 Pontevedra, Spain;
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas (CICA), Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Spain; (R.U.-V.); (D.E.-G.)
| | - Zoltán Garda
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary; (F.K.K.); (V.N.); (Z.G.); (R.M.)
| | - Kristof Pota
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 West Bowie Street, Fort Worth, TX 76109, USA;
| | - Roland Mezei
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary; (F.K.K.); (V.N.); (Z.G.); (R.M.)
| | - Agnès Pallier
- Centre de Biophysique Moléculaire, CNRS, UPR 4301, Rue Charles-Sadron, CEDEX 2, 45071 Orléans, France;
| | - Éva Tóth
- Centre de Biophysique Moléculaire, CNRS, UPR 4301, Rue Charles-Sadron, CEDEX 2, 45071 Orléans, France;
- Correspondence: (É.T.); (C.P.-I.); (G.T.); Tel.: +33-2-38-25-76-25 (É.T.); +34-881-5597 (C.P.-I.); +36-52-512-900 (ext. 22374) (G.T.)
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA), Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 15071 A Coruña, Spain; (R.U.-V.); (D.E.-G.)
- Correspondence: (É.T.); (C.P.-I.); (G.T.); Tel.: +33-2-38-25-76-25 (É.T.); +34-881-5597 (C.P.-I.); +36-52-512-900 (ext. 22374) (G.T.)
| | - Gyula Tircsó
- Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary; (F.K.K.); (V.N.); (Z.G.); (R.M.)
- Correspondence: (É.T.); (C.P.-I.); (G.T.); Tel.: +33-2-38-25-76-25 (É.T.); +34-881-5597 (C.P.-I.); +36-52-512-900 (ext. 22374) (G.T.)
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Chang CA, Lee HY, Lin SL, Meng CN, Wu TT. Dinuclear Lanthanide(III)-m-ODO2A-dimer Macrocyclic Complexes: Solution Speciation, DFT Calculations, Luminescence Properties, and Promoted Nitrophenyl-Phosphate Hydrolysis Rates. Chemistry 2018; 24:6442-6457. [PMID: 29479746 DOI: 10.1002/chem.201800037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Indexed: 12/24/2022]
Abstract
Potentiometric speciation studies, mass spectrometry, and DFT calculations helped to predict the various structural possibilities of the dinuclear trivalent lanthanide ion (LnIII , Ln=La, Eu, Tb, Yb, Y) complexes of a novel macrocyclic ligand, m-ODO2A-dimer (H4 L), to correlate with their luminescence properties and the promoted BNPP and HPNP phosphodiester bond hydrolysis reaction rates. The stability constants of the dinuclear Ln2 (m-ODO2A-dimer) complexes and various hydrolytic species confirmed by mass spectrometry were determined. DFT calculations revealed that the Y2 LH-1 and the Y2 LH-2 species tended to form structures with the respective closed- and open-form conformations. Luminescence lifetime data for the heterodimetallic TbEuL system confirmed the fluorescence resonance energy transfer from the TbIII to EuIII ion. The internuclear distance RTbEu values were estimated to be in the range of 9.4-11.3 Å (pH 6.7-10.6), which were comparable to those of the DFT calculated open-form conformations. Multiple linear regression analysis of the kobs data was performed using the equation: kobs,corr. =kobs -kobs,OH =kLn2LHM->1 [Ln2 LH-1 ]+kLn2LH-2 [Ln2 LH-2 ] for the observed Ln2 L-promoted BNPP/HPNP hydrolysis reactions in solution pH from 7 to 10.5 (Ln=Eu, Yb). The results showed that the second-order rate constants for the Eu2 LH-2 and Yb2 LH-2 species were about 50-400 times more reactive than the structural analogous Zn2 (m-12 N3 O-dimer) system.
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Affiliation(s)
- C Allen Chang
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong St., Beitou, Taipei, Taiwan), 112, Republic of China.,Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei, 112, Taiwan, Republic of China.,Molecular Imaging Research Center (MIRC), National Yang-Ming University, Taipei, 112, Taiwan, Republic of China.,Department of Biological Science and Technology, National Chiao Tung University, No. 75 Po-Ai Street, Hsinchu, Taiwan, 30039, Republic of China
| | - Hwa-Yu Lee
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong St., Beitou, Taipei, Taiwan), 112, Republic of China
| | - Syue-Liang Lin
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, No. 155, Sec. 2, Li-Nong Street, Taipei, 112, Taiwan, Republic of China
| | - Ching-Ning Meng
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong St., Beitou, Taipei, Taiwan), 112, Republic of China
| | - Tsung-Ta Wu
- Department of Biological Science and Technology, National Chiao Tung University, No. 75 Po-Ai Street, Hsinchu, Taiwan, 30039, Republic of China
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5
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Lima LMP, Beyler M, Delgado R, Platas-Iglesias C, Tripier R. Investigating the Complexation of the Pb(2+)/Bi(3+) Pair with Dipicolinate Cyclen Ligands. Inorg Chem 2015; 54:7045-57. [PMID: 26146022 DOI: 10.1021/acs.inorgchem.5b01079] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The complexation properties toward Pb(2+) and Bi(3+) of the macrocyclic ligands 6,6'-((1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene))dipicolinic acid (H2do2pa) and 6,6'-((4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene))dipicolinic acid (H2Me-do2pa) have been investigated. A new three-step synthesis of H2do2pa following the bisaminal methodology has also been developed. The X-ray structures of [Pb(Me-do2pa)]·6H2O and [Bi(Me-do2pa)](NO3)·H2O show that the two metal ions are eight-coordinated by the ligand. The two complexes exist as the racemic Δ(δδδδ)/Λ(λλλλ) mixture both in the solid state and in solution, as indicated by NMR and DFT studies. The stability constants of the lead(II) and bismuth(III) complexes of the two ligands were determined in 0.5 M KCl using potentiometric and spectrophotometric techniques. The stability constants determined for the complexes of Pb(2+) are relatively high (log KML = 16.44 and 18.44 for H2do2pa and H2Me-do2pa, respectively) and exceptionally high for the complexes of Bi(3+) (log KML = 32.0 and 34.2 for H2do2pa and H2Me-do2pa, respectively). The [Pb(Me-do2pa)] complex presents rather fast formation and very good kinetic inertness toward transchelation. Additionally, the [Bi(Me-do2pa)](+) complex was found to present a remarkably fast complexation rate (full complexation in ∼2 min at pH 5.0, acetate buffer) and a very good kinetic inertness with respect to metal ion dissociation (half-life of 23.9 min in 1 M HCl), showing promise for potential applications in α-radioimmunotherapy.
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Affiliation(s)
- Luís M P Lima
- †Université de Bretagne Occidentale, UMR-CNRS 6521, UFR des Sciences et Techniques, 6 avenue Victor le Gorgeu, C.S. 93837, 29238 BREST Cedex 3, France.,‡Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Maryline Beyler
- †Université de Bretagne Occidentale, UMR-CNRS 6521, UFR des Sciences et Techniques, 6 avenue Victor le Gorgeu, C.S. 93837, 29238 BREST Cedex 3, France
| | - Rita Delgado
- ‡Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Carlos Platas-Iglesias
- §Departamento de Química Fundamental, Facultade de Ciencias, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Raphaël Tripier
- †Université de Bretagne Occidentale, UMR-CNRS 6521, UFR des Sciences et Techniques, 6 avenue Victor le Gorgeu, C.S. 93837, 29238 BREST Cedex 3, France
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Regueiro-Figueroa M, Ruscsák E, Fra L, Tircsó G, Tóth I, de Blas A, Rodríguez-Blas T, Platas-Iglesias C, Esteban-Gómez D. Highly Stable Complexes of Divalent Metal Ions (Mg2+, Ca2+, Cu2+, Zn2+, Cd2+, and Pb2+) with a Dota-Like Ligand Containing a Picolinate Pendant. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402693] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Chang CA, Lee HY, Chen CL. Simulated annealing and density functional theoretical prediction of macrocyclic ligand conformations, protonation sites and complex metal–ligand exchange reaction directions. Dalton Trans 2013; 42:6397-409. [DOI: 10.1039/c3dt32113d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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8
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Regueiro-Figueroa M, Bensenane B, Ruscsák E, Esteban-Gómez D, Charbonnière LJ, Tircsó G, Tóth I, de Blas A, Rodríguez-Blas T, Platas-Iglesias C. Lanthanide dota-like complexes containing a picolinate pendant: structural entry for the design of Ln(III)-based luminescent probes. Inorg Chem 2011; 50:4125-41. [PMID: 21456610 DOI: 10.1021/ic2001915] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In this contribution we present two ligands based on a do3a platform containing a picolinate group attached to the fourth nitrogen atom of the cyclen unit, which are designed for stable lanthanide complexation in aqueous solutions. Potentiometric measurements reveal that the thermodynamic stability of the complexes is very high (log K = 21.2-23.5), being comparable to that of the dota analogues. Luminescence lifetime measurements performed on solutions of the Eu(III) and Tb(III) complexes indicate that the complexes are nine coordinate with no inner-sphere water molecules. A combination of density functional theory (DFT) calculations and NMR measurements shows that for the complexes of the heaviest lanthanides there is a major isomer in solution consisting of the enantiomeric pair Λ(δδδδ) and Δ(λλλλ), which provides square antiprismatic coordination (SAP) around the metal ion. Analysis of the Yb(III)-induced paramagnetic shifts unambiguously confirms that these complexes have SAP coordination in aqueous solution. For the light lanthanide ions however both the SAP and twisted-square antiprismatic (TSAP) isomers are present in solution. Inversion of the cyclen ring appears to be the rate-determining step for the Λ(δδδδ) ↔ Δ(λλλλ) enantiomerization process observed in the Lu(III) complexes. The energy barriers obtained from NMR measurements for this dynamic process are in excellent agreement with those predicted by DFT calculations. The energy barriers calculated for the arm-rotation process are considerably lower than those obtained for the ring-inversion path. Kinetic studies show that replacement of an acetate arm of dota by a picolinate pendant results in a 3-fold increase in the formation rate of the corresponding Eu(III) complexes and a significant increase of the rates of acid-catalyzed dissociation of the complexes. However, these rates are 1-2 orders of magnitude lower than those of do3a analogues, which shows that the complexes reported herein are remarkably inert with respect to metal ion dissociation.
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Affiliation(s)
- Martín Regueiro-Figueroa
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain
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9
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Ferreirós-Martínez R, Platas-Iglesias C, de Blas A, Esteban-Gómez D, Rodríguez-Blas T. Macrocyclic Receptor Showing Improved PbII/ZnII and PbII/CaII Selectivities. Eur J Inorg Chem 2010. [DOI: 10.1002/ejic.200901219] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Ferreirós-Martínez R, Esteban-Gómez D, de Blas A, Platas-Iglesias C, Rodríguez-Blas T. Eight-coordinate Zn(II), Cd(II), and Pb(II) complexes based on a 1,7-diaza-12-crown-4 platform endowed with a remarkable selectivity over Ca(II). Inorg Chem 2010; 48:11821-31. [PMID: 19911785 DOI: 10.1021/ic901883h] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thermodynamic stability of the Pb(II), Cd(II), Zn(II), and Ca(II) complexes with the dianionic macrocyclic ligand N,N'-bis[(6-carboxy-2-pyridyl)methyl]-1,7-diaza-12-crown-4 (H(2)bp12c4) has been investigated by pH-potentiometric titrations at 25 degrees C in 0.1 M KNO(3). The stability constants vary in the following order: Cd(II) > Zn(II) approximately Pb(II) > Ca(II). As a consequence, H(2)bp12c4 present an important Cd(II)/Ca(II) selectivity, as well as a certain selectivity for Cd(II) over Zn(II). To rationalize these results, a detailed investigation of the structure of these complexes has been carried out both in solid state and in aqueous solution. Furthermore, the [M(bp12c4)] complexes (M = Ca, Zn, Cd, or Pb) were characterized by means of density functional theory (DFT) calculations (B3LYP model) to obtain information on their solution structures and to investigate the possible stereochemical activity of the Pb(II) lone pair. Our results show that in all cases the metal ion is octacoordinated by the ligand, a situation that is particularly rare for Zn(II) complexes. The coordination polyhedra observed in the solid state for the [M(bp12c4)] complexes (M = Zn, Cd, or Ca) is closely related to the conformation adopted by the ligand in the corresponding complex: The Zn(II) complex adopts a Delta(lambdalambdalambdalambda) conformation in the solid state, which results in a square antiprismatic coordination, while the Delta(deltadeltadeltadelta) conformation observed for the Cd(II) and Ca(II) analogues yields inverted-square antiprismatic geometries. The X-ray crystal structure of the Pb(II) analogue shows that the metal ion is directly bound to the eight donor atoms of the ligand, but the bond distances of the metal coordination environment indicate an asymmetrical coordination of the cation by the ligand, which is attributed to the stereochemical activity of the Pb(II) lone pair. In aqueous solution the Ca(II), Zn(II), and Cd(II) complexes show rigid C(2) symmetries, while the Pb(II) analogue presents a more flexible structure.
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Affiliation(s)
- Raquel Ferreirós-Martínez
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, Spain
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11
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Pálinkás Z, Roca-Sabio A, Mato-Iglesias M, Esteban-Gómez D, Platas-Iglesias C, de Blas A, Rodríguez-Blas T, Tóth É. Stability, Water Exchange, and Anion Binding Studies on Lanthanide(III) Complexes with a Macrocyclic Ligand Based on 1,7-Diaza-12-crown-4: Extremely Fast Water Exchange on the Gd3+ Complex. Inorg Chem 2009; 48:8878-89. [DOI: 10.1021/ic9011197] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zoltán Pálinkás
- Centre de Biophysique Moléculaire, CNRS, rue Charles Sadron, 45071 Orléans, Cedex 2, France
| | - Adrián Roca-Sabio
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - Marta Mato-Iglesias
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - David Esteban-Gómez
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - Carlos Platas-Iglesias
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - Andrés de Blas
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - Teresa Rodríguez-Blas
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Alejandro de la Sota 1, 15008 A Coruña, Spain
| | - Éva Tóth
- Centre de Biophysique Moléculaire, CNRS, rue Charles Sadron, 45071 Orléans, Cedex 2, France
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Siaugue JM, Favre-Réguillon A, Dioury F, Plancque G, Foos J, Madic C, Moulin C, Guy A. Effect of Mixed Pendant Groups on the Solution Properties of 12-Membered Azapyridinomacrocycles: Evaluation of the Protonation Constants and the Stability Constants of the Europium(III) Complexes. Eur J Inorg Chem 2003. [DOI: 10.1002/ejic.200300016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Delgado R, de Fátima Cabral M, Castanheira R, Zhang A, Herrmann R. Metal complexes of edta-derived macrocyclic ether bis(lactones). Hydrolysis of the macrocycles and the metal catalysis effect. Polyhedron 2002. [DOI: 10.1016/s0277-5387(02)01162-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Chaves S, Cerva A, Delgado R. 13-Membered macrocycles and their complexometric properties: study of 7,11-bis(carboxymethyl)-1,4-dioxa-7,11-diazacyclotridecane. Polyhedron 1998. [DOI: 10.1016/s0277-5387(97)00246-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Costa J, Delgado R, do Carmo Figueira M, T. Henriques R, Teixeira M. Metal complexes of a tetraaza macrocycle with N-carboxymethyl groups as pendant arms. ACTA ACUST UNITED AC 1997. [DOI: 10.1039/a602948e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cabral MF, Delgado R. Metal Complexes of Pentadentate Macrocyclic Ligands Containing Oxygen and Nitrogen as Donor Atoms. Helv Chim Acta 1994. [DOI: 10.1002/hlca.19940770212] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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