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001-es BibID:BIBFORM103530
035-os BibID:(WOS)000541873600033 (Scopus)85084399701
Első szerző:Garda Zoltán (vegyész)
Cím:Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cyclen-Based Ligands across the Lanthanide Series / Zoltán Garda, Viktoria Nagy, Aurora Rodríguez-Rodríguez, Rosa Pujales-Paradela, Véronique Patinec, Goran Angelovski, Éva Tóth, Ferenc K. Kálmán, David Esteban-Gómez, Raphaël Tripier, Carlos Platas-Iglesias, Gyula Tircsó
Dátum:2020
ISSN:0020-1669 1520-510X
Megjegyzések:We report a detailed study of the thermodynamic stability and dissociation kinetics of lanthanide complexes with two ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms linked to two nitrogen atoms of the macrocycle in either cis (1,4-H(3)DO2APA) or trans (1,7-H(3)DO2APA) positions. The stability constants of the Gd3+ complexes with these two ligands are very similar, with log K-GdL values of 16.98 and 16.33 for the complexes of 1,4-H(3)DO2APA and 1,7-H(3)DO2APA, respectively. The stability constants of complexes with 1,4-H(3)DO2APA follow the usual trend, increasing from log K-LaL = 15.96 to log K-LuL = 19.21. However, the stability of [Ln(1,7-DO2APA)] complexes decreases from log K = 16.33 for Gd3+ to 14.24 for Lu3+. The acid-catalyzed dissociation rates of the Gd3+ complexes differ by a factor of similar to 15, with rate constants (k(1)) of 1.42 and 23.5 M(-1)s(-1) for [Gd(1,4-DO2APA)] and [Gd(1,7DO2APA)], respectively. This difference is magnified across the lanthanide series to reach a 5 orders of magnitude higher k(1) for [Yb(1,7-DO2APA)] (1475 M(-1)s(-1)) than for [Yb(1,4-DO2APA)] (5.79 x 10(-3)M(-1)s(-1)).The acid catalyzed mechanism involves the protonation of a carboxylate group, followed by a cascade of proton-transfer events that result in the protonation of a nitrogen atom of the cyclen unit. Density functional theory calculations suggest a correlation between the strength of the Ln-O-carboxylate bonds and the kinetic inertness of the complex, with stronger bonds providing more inert complexes. The H-1 NMR resonance of the coordinated water molecule in the [Yb(1,7-DO2APA)] complex at 176 ppm provides a sizable chemical exchange saturation transfer effect thanks to a slow water exchange rate of (15.9 +/- 1.6) x 10(3) s(-1).
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Inorganic Chemistry. - 59 : 12 (2020), p. 8184-8195. -
További szerzők:Nagy Viktória Rodríguez-Rodríguez, Aurora Pujales-Paradela, Rosa Patinec, Véronique Angelovski, Goran Tóth Éva Kálmán Ferenc K. (1978-) (vegyész) Esteban-Gómez, David Tripier, Raphaël Platas-Iglesias, Carlos Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:GINOP-2.3.2-15-2016-00008
GINOP
NKFIH-K-120224
Egyéb
NKFIH-K-128201
Egyéb
2019-2.1.11-TÉT-2019-00084
Egyéb
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2.

001-es BibID:BIBFORM076226
035-os BibID:(WoS)000433013600028 (Scopus)85047315800
Első szerző:Gündüz, Serhat
Cím:Coordination Properties of GdDO3A-Based Model Compounds of Bioresponsive MRI Contrast Agents / Serhat Gündüz, Sandip Vibhute, Richard Botár, Ferenc K. Kálmán, Imre Tóth, Gyula Tircsó, Martín Regueiro-Figueroa, David Esteban-Gómez, Carlos Platas-Iglesias, Goran Angelovski
Dátum:2018
ISSN:0020-1669 1520-510X
Megjegyzések:We report a detailed characterization of the thermodynamic stability and dissociation kinetics of Gd3+ complexes with DO3A derivatives containing a (methylethylcarbamoylmethylamino)acetic acid (L1), (methylpropylcarbamoylmethylamino)acetic acid (L2), 2-dimethylamino-N-ethylacetamide (L3), or 2-dimethylamino-N-propylacetamide (L4) group attached to the fourth nitrogen atom of the macrocyclic unit. These ligands are model systems of Ca2+- and Zn2+-responsive contrast agents (CA) for application in magnetic resonance imaging (MRI). The results of the potentiometric studies (I = 0.15 M NaCl) provide stability constants with log KGdL values in the range 13.9?14.8. The complex speciation in solution was found to be quite complicated due to the formation of protonated species at low pH, hydroxido complexes at high pH, and stable dinuclear complexes in the case of L1,2. At neutral pH significant fractions of the complexes are protonated at the amine group of the amide side chain (log KGdL?H = 7.2?8.1). These ligands form rather weak complexes with Mg2+ and Ca2+ but very stable complexes with Cu2+ (log KCuL = 20.4?22.3) and Zn2+ (log KZnL = 15.5?17.6). Structural studies using a combination of 1H NMR and luminescence spectroscopy show that the amide group of the ligand is coordinated to the metal ion at pH ?8.5, while protonation of the amine group provokes the decoordination of the amide O atom and a concomitant increase in the hydration number and proton relaxivity. The dissociation of the complexes occurs mainly through a rather efficient proton-assisted pathway, which results in kinetic inertness comparable to that of nonmacrocyclic ligands such as DTPA rather than DOTA-like complexes.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Inorganic Chemistry. - 57 : 10 (2018), p. 5973-5986. -
További szerzők:Vibhute, Sandip Botár Richárd (1992-) (vegyész) Kálmán Ferenc K. (1978-) (vegyész) Tóth Imre (1950-) (vegyész) Tircsó Gyula (1977-) (vegyész, kémia tanár) Regueiro-Figueroa, Martín Esteban-Gómez, David Platas-Iglesias, Carlos Angelovski, Goran
Pályázati támogatás:GINOP-2.3.2-15-2016-00008
GINOP
GINOP-2.3.3-15-2016-00004
GINOP
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Intézményi repozitóriumban (DEA) tárolt változat
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3.

001-es BibID:BIBFORM100007
035-os BibID:(WoS)000739628200001 (Scopus)85123758171
Első szerző:Pérez-Lourido, Paulo
Cím:Stable and inert macrocyclic cobalt(II) and nickel(II) complexes with paraCEST response / Paulo Pérez-Lourido, Enikő Madarasi, Fanni Antal, David Esteban-Gómez, Gaoji Wang, Goran Angelovski, Carlos Platas-Iglesias, Gyula Tircsó, Laura Valencia
Dátum:2022
ISSN:1477-9226
Megjegyzések: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 oC .
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
paraCEST
PC2A-bis(amides)
stability
inertnes, structure
Megjelenés:Dalton Transactions. - 51 : 4 (2022), p. 1580-1593. -
További szerzők:Madarasi Enikő Antal Fanni Esteban-Gómez, David Wang, Gaoji Angelovski, Goran Platas-Iglesias, Carlos Tircsó Gyula (1977-) (vegyész, kémia tanár) Valencia, Laura
Pályázati támogatás:K-120224
OTKA
K-134694
OTKA
Doctoral School of Chemistry at the University of Debrecen, Debrecen, Hungary
Egyéb
COST Action CA15209 "European Network on NMR Relaxometry
Egyéb
Bilateral Hungarian-Spanish Science and Technology Cooperation Program (2019-2.1.11- TET-2019-00084 supported by NKFIH).
Egyéb
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