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001-es BibID:	BIBFORM106980
035-os BibID:	(WoS)000643574200067 (Scopus)85100045839
Első szerző:	Garda Zoltán (vegyész)
Cím:	Complexation of Mn(II) by Rigid Pyclen Diacetates: Equilibrium, Kinetic, Relaxometric, Density Functional Theory, and Superoxide Dismutase Activity Studies / Zoltán Garda, Enikő Molnár, Nadège Hamon, José Luis Barriada, David Esteban-Gómez, Balázs Váradi, Viktória Nagy, Kristof Pota, Ferenc Krisztián Kálmán, Imre Tóth, Norbert Lihi, Carlos Platas-Iglesias, Éva Tóth, Raphaël Tripier, Gyula Tircsó
Dátum:	2021
ISSN:	0020-1669 1520-510X
Megjegyzések:	We report the Mn(II) complexes with two pyclen-based ligands (pyclen = 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene) functionalized with acetate pendant arms at either positions 3,6 (3,6-PC2A) or 3,9 (3,9-PC2A) of the macrocyclic fragment. The 3,6-PC2A ligand was synthesized in five steps from pyclen oxalate by protecting one of the secondary amine groups of pyclen using Alloc protecting chemistry. The complex with 3,9-PC2A is characterized by a higher thermodynamic stability [log K-MnL = 17.09(2)] than the 3,6-PC2A analogue [log K-MnL = 15.53(1); 0.15 M NaCl]. Both complexes contain a water molecule coordinated to the metal ion, which results in relatively high H-1 relaxivities (r(1p) = 2.72 and 2.91 mM(-1) s(-1) for the complexes with 3,6-PC2A and 3,9-PC2A, respectively, at 25 degrees C and 0.49 T). The coordinated water molecule displays fast exchange kinetics with the bulk in both cases; the rates (k(ex)(298)) are 140 x 10(6) and 126 x 10(6) s(-1) for [Mn(3,6-PC2A)(H2O)] and [Mn(3,9-PC2A)(H2O)], respectively. The two complexes were found to be remarkably inert with respect to their dissociation, with half-lives of 63 and 21 h, respectively, at pH = 7.4 in the presence of excess Cu(II). The r(1p) values recorded in blood serum remain constant at least over a period of 120 h. Cyclic voltammetry experiments show irreversible oxidation features shifted to higher potentials with respect to [Mn(EDTA)(H2O)](2-) (H(4)EDTA = ethylenediaminetetraacetic acid) and [Mn(PhDTA)(H2O)](2-) (H(4)PhDTA = phenylenediamine-N,N,N',N'-tetraacetic acid), indicating that the PC2A complexes reported here have a lower tendency to stabilize Mn(III). The superoxide dismutase activity of the Mn(II) complexes was tested using the xanthine/xanthine oxidase/p-nitro blue tetrazolium chloride assay at pH = 7.8. The Mn(II) complexes of 3,6-PC2A and 3,9-PC2A are capable of assisting decomposition of the superoxide anion radical. The kinetic rate constant of the complex of 3,9-PC2A is smaller by 1 order of magnitude than that of 3,6-PC2A.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Inorganic Chemistry. - 60 : 2 (2021), p. 1133-1148. -
További szerzők:	Molnár Enikő (1991-) (vegyész) Hamon, Nadège Barriada, José Luis Esteban-Gómez, David Váradi Balázs (1990-) (vegyész) Nagy Viktória Póta Kristóf Kálmán Ferenc K. (1978-) (vegyész) Tóth Imre (1950-) (vegyész) Lihi Norbert (1990-) (vegyész) Platas-Iglesias, Carlos Tóth Éva (1967-) (koordinációs kémia) Tripier, Raphaël Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:	K-120224 OTKA 128201 OTKA 134694 OTKA PD-128326 OTKA 2019-2.1.11- 1179 TET-2019-00084 Egyéb
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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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001-es BibID:	BIBFORM106987
035-os BibID:	(Wos)000645403400001 (Scopus)85103919865 (cikkazonosító)1524
Első szerző:	Kálmán Ferenc K. (vegyész)
Cím:	Expanding the Ligand Classes Used for Mn(II) Complexation: Oxa-aza Macrocycles Make the Difference / Ferenc K. Kálmán, Viktória Nagy, Rocío Uzal-Varela, Paulo Pérez-Lourido, David Esteban-Gómez,Zoltán Garda, Kristof Pota, Roland Mezei, Agnès Pallier, Éva Tóth, Carlos Platas-Iglesias, Gyula Tircsó
Dátum:	2021
ISSN:	1420-3049
Megjegyzések:	We report two macrocyclic ligands based on a 1,7-diaza-12-crown-4 platform functionalizedwith acetate (tO2DO2A2?) or piperidineacetamide (tO2DO2AMPip) pendant arms and a detailed char-acterization of the corresponding Mn(II) complexes. The X?ray structure of [Mn(tO2DO2A)(H2O)]·2H2Oshows that the metal ion is coordinated by six donor atoms of the macrocyclic ligand and one watermolecule, to result in seven-coordination. The Cu(II) analogue presents a distorted octahedral coor-dination environment. The protonation constants of the ligands and the stability constants of thecomplexes formed with Mn(II) and other biologically relevant metal ions (Mg(II), Ca(II), Cu(II) andZn(II)) were determined using potentiometric titrations (I= 0.15 M NaCl, T = 25?C). The conditionalstabilities of Mn(II) complexes at pH 7.4 are comparable to those reported for the cyclen-basedtDO2A2?ligand. The dissociation of the Mn(II) chelates were investigated by evaluating the rateconstants 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?assistedpathways, while the [Mn(tO2DO2AMPip)(H2O)] analogue dissociates through spontaneous andproton-assisted mechanisms. The Mn(II) complex oftO2DO2A2 is remarkably inert with respectto its dissociation, while the amide analogue is significantly more labile. The presence of a watermolecule coordinated to Mn(II) imparts relatively high relaxivities to the complexes. The parametersdetermining this key property were investigated using17O NMR (Nuclear Magnetic Resonance)transverse relaxation rates and1H nuclear magnetic relaxation dispersion (NMRD) profiles.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk manganese magnetic resonance imaging stability dissociation kinetics water exchange contrast agents macrocycles
Megjelenés:	Molecules. - 26 : 6 (2021), p. 1-20. -
További szerzők:	Nagy Viktória Uzal-Varela, Rocío Pérez-Lourido, Paulo Esteban-Gómez, David Garda Zoltán (1989-) (vegyész) Póta Kristóf Mezei Roland Pallier, Agnès Tóth Éva Platas-Iglesias, Carlos Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:	K-120224 OTKA K-134694 OTKA
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