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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:	BIBFORM123175
Első szerző:	Tóth Éva (koordinációs kémia)
Cím:	Small, Fluorinated Mn2+ Chelate as an Efficient 1H and 19F MRI Probe / Éva Tóth, Zoltán Garda, Frédéric Szeremeta, Océane Quin, Enikő Molnár, Balázs Váradi, Rudy Clémençon, Sandra Même, Chantal Pichon, Gyula Tircsó
Dátum:	2024
ISSN:	1433-7851 1521-3773
Megjegyzések:	We explore the potential of fluorine-containing small Mn2+chelates as alternatives to perfluorinated nanoparticles, widely usedas 19F MRI probes. In MnL1, the cyclohexanediamine skeleton andtwo piperidine rings, involving each a metal-coordinating amide groupand an appended CF3 moiety, provide high rigidity to the complex.This allows for good control of the Mn-F distance (rMnF = 8.2?0.2 ?Adetermined from 19F relaxation data), as well as for high kineticinertness (a dissociation half-life of 1285 h is estimated forphysiological conditions). The paramagnetic Mn2+ leads to a ~150-foldacceleration of the longitudinal 19F relaxation, with moderate line-broadening effect, resulting in T2/T1 ratios of 0.8 (9.4 T). Owing to itsinner sphere water molecule, MnL1 is a good 1H relaxation agent aswell (r1 = 5.36 mM-1s-1 at 298K, 20MHz). MnL1 could be readilyvisualized in 19F MRI by using fast acquisition techniques, both inphantom images and living mice following intramuscular injection, withremarkable signal-to-noise ratios and short acquisition times. Whileapplications in targeted imaging or cell therapy monitoring requirefurther optimisation of the molecular structure, these results argue forthe potential of such small, monohydrated and fluorinated Mn2+complexes for combined 19F and 1H MRI detection.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk 19F MRI manganese contrast agent paramagnetic 1H MRI
Megjelenés:	Angewandte Chemie-International Edition. - [Epub ahead of print] : - (2024), p. 1-9. -
További szerzők:	Garda Zoltán (1989-) (vegyész) Szeremeta, Frédéric Quin, Océane Molnár Enikő (1991-) (vegyész) Váradi Balázs (1990-) (vegyész) Clémençon, Rudy Même, Sandra Pichon, Chantal Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:	PD-138064 OTKA K-134694 OTKA University of Debrecen Publication Fund Egyéb European Union's Horizon 2021 research and innovationprogramme under the Marie Skodowska-Curie grant agreement No. 101065389 Egyéb
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001-es BibID:	BIBFORM073151
035-os BibID:	(WoS)000405972200021 (Scopus)85024393994
Első szerző:	Vanasschen, Christian
Cím:	Novel CDTA-based, Bifunctional Chelators for Stable and Inert Mn Complexation: Synthesis and Physicochemical Characterization / Christian Vanasschen, Enikő Molnár, Gyula Tircsó, Ferenc K. Kálmán, Éva Tóth, Marie Brandt, Heinz H. Coenen, Bernd Neumaier
Dátum:	2017
ISSN:	0020-1669
Megjegyzések:	In the search for MnII MR and PET/MR imaging agentswith optimal balance between thermodynamic stability, kinetic inertness, and relaxivity, two novel bifunctional MnII chelators (BFMnCs) based on CDTA (trans-1,2-diaminocyclohexane-N,N,N·,N·-tetraacetic acid) weresynthesized. A six-step synthesis, involving the buildup of a functionalized trans-1,2-diaminocyclohexane core, provided CuAAC-reactive 6a and 6b bearing an alkyne or azide substituent on the cyclohexane ring, respectively (CuAAC = CuI-catalyzed azide?alkyne 1,3-dipolar cycloaddition).Thermodynamic, kinetic, and relaxometric studies wereperformed with 4-HET-CDTA (8a) as a "model chelator," synthesized in two steps from 6a. The protonation constants revealed that 8a is slightly less basic than CDTA and forms a MnII complex of marginally lower thermodynamic stability (log KMnL = 13.80 vs 14.32, respectively), while the conditional stability constant is almost identical for both chelates (pMn = 8.62 vs 8.68, respectively). Kinetic assessment of the CuII-mediated transmetalation of [Mn(4-HET-CDTA)]2? showed that proton-assisted complex dissociation is slightly slower than for [Mn(CDTA)]2? (k1 = 297 vs 400 M?1 s?1, respectively). Importantly, the dissociation half-life near physiological conditions (pH 7.4, 25 ?C) underlined that [Mn(4-HET-CDTA)]2? is ?35% more inert (t1/2 = 16.2 vs 12.1 h, respectively). Those findings may be accounted for by a combination of reduced basicity and increased rigidity of the ligand. Analysis of the17O NMR and 1H NMRD data attributed the high relaxivity of [Mn(4-HET-CDTA)]2? (r1 = 4.56 mM?1 s?1 vs 3.65 mM?1 s?1for [Mn(CDTA)]2?; 20 MHz, 25 ?C) to slower rotational dynamics (?R298 = 105 ps). Additionally, the fast water exchange of the complex correlates well with the value reported for [Mn(CDTA)]2? (kex298 = 17.6 ? 107 vs 14.0 ? 107 s?1, respectively). Given the exquisite compromise between thermodynamic stability, kinetic inertness, and relaxivity achieved by [Mn(4-HET-CDTA)]2?, appropriately designed CuAAC-conjugates of 6a/6b are promising precursors for the preparation of targeted, bioresponsive, or high relaxivity manganese-based PET/MR tracers (52g/55 MnII) and MR contrast agents (MnII).
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk Bifunctional chelators Manganese(II) complexes Alternative MRI contrast agents Stability Inertness
Megjelenés:	Inorganic Chemistry. - 56 : 14 (2017), p. 7746-7760. -
További szerzők:	Molnár Enikő (1991-) (vegyész) Tircsó Gyula (1977-) (vegyész, kémia tanár) Kálmán Ferenc K. (1978-) (vegyész) Tóth Éva (1967-) (koordinációs kémia) Brandt, Marie Coenen, Heinz H. Neumaier, Bernd
Pályázati támogatás:	K-120224 OTKA János Bolyai Research Scholarship of the Hungarian Academy of Sciences Egyéb GINOP-2.3.2-15-2016-00008 GINOP Le Studium, Loire Valley Institute for Advanced Studies Egyéb
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