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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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2.

001-es BibID:BIBFORM062902
Első szerző:Kálmán Ferenc K. (vegyész)
Cím:H4octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II) / Ferenc Krisztián Kálmán, Andrea Végh, Martín Regueiro-Figueroa, Éva Tóth, Carlos Platas-Iglesias, Gyula Tircsó
Dátum:2015
ISSN:0020-1669
Megjegyzések:The acyclic ligand octapa4 (H4octapa = 6,6'-((ethane-1,2-diylbis((carboxymethyl)azanediyl))bis(methylene))dipicolinic acid) forms stable complexes with the Ln3+ ions in aqueous solution. The stability constants determined for the complexes with La3+, Gd3+ and Lu3+ using relaxometric methods are logKLaL = 20.13(7), logKGdL = 20.23(4) and logKLuL = 20.49(5) (I = 0.15 M NaCl). High stability constants were also determined for the complexes formed with divalent metal ions such as Zn2+ and Cu2+ (logKZnL = 18.91(3) and logKCuL = 22.08(2)). A UV-Vis and NMR spectroscopic study and DFT calculations point to hexadentate binding of the ligand to Zn2+ and Cu2+, the donor atoms of the acetate groups of the ligand remaining uncoordinated. The complexes formed with the Ln3+ ions are nine-coordinated thanks to the octadentate binding of the ligand and the presence of a coordinated water molecule. The stability constants of the complexes formed with the Ln3+ ions do not change significantly across the lanthanide series. A DFT investigation shows that this is the result of a subtle balance between the increased binding energies across the 4f period, which contribute to an increasing complex stability, and the parallel increase of the absolute values of the hydration free energies of the Ln3+ ions. In the case of the [Ln(octapa)(H2O)] complexes the interaction between the amine nitrogen atoms of the ligand and the Ln3+ ions is weakened along the lanthanide series, and therefore the increased electrostatic interaction does not overcome the increasing hydration energies. A detailed kinetic study of the dissociation of the [Gd(octapa)(H2O)] complex in the presence of Cu2+ shows that the metal-assisted pathway is the main responsible for complex dissociation at pH 7.4 and physiological [Cu2+] concentration (1 uM).
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Magnetic Resonance Imaging
Complexes
Equilibrium
Kinetics
DFT calculation
Megjelenés:Inorganic Chemistry. - 54 : 5 (2015), p. 2345-2356. -
További szerzők:Végh Andrea (vegyész) Regueiro-Figueroa, Martín Tóth Éva (1967-) (koordinációs kémia) Platas-Iglesias, Carlos Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:Centro de Supercomputación de Galicia (CESGA)
Egyéb
COST Actions CM1006 "European F-Element Network (EuFen)" and TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging-Guided Drug Delivery"
Egyéb
K-84291
OTKA
K-109029
OTKA
Hungarian-French bilateral Scientific and Technological Cooperation (project # TÉT_11-2-2012-0010 and PHC Balaton)
Egyéb
János Bolyai Research Scholarship of the Hungarian Academy of Sciences.
MTA
TÁMOP 4.2.2.A-11/1/KONV-2012-0043
TÁMOP
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3.

001-es BibID:BIBFORM062881
035-os BibID:(WoS)000368906200009 (Scopus)84954489502
Első szerző:Tircsó Gyula (vegyész, kémia tanár)
Cím:Approaching the Kinetic Inertness of Macrocyclic Gadolinium(III)-Based MRI Contrast Agents with Highly Rigid Open-Chain Derivatives / Gyula Tircsó, Martín Regueiro-Figueroa, Viktória Nagy, Zoltán Garda, Tamás Garai, Ferenc Krisztián Kálmán, David Esteban-Gómez, Éva Tóth, Carlos Platas-Iglesias
Dátum:2016
ISSN:0947-6539
Megjegyzések:A highly rigid open-chain octadentate ligand (H4cddadpa), containing a diaminecyclohexane unit to replace the ethylenediamine bridge of 6,6'-((ethane-1,2 diylbis((carboxymethyl)azanediyl))bis(methylene))dipicolinic acid (H4octapa), was synthesized. This structural modification slightly improves the thermodynamic stability of the Gd3+ complex (logKGdL = 20.68 vs 20.23 for [Gd(octapa)]-), while other MRI-relevant parameters remain practically unaffected (number of coordinated water molecules, q=1; relaxivity, r1 =5.73 m?-1s-1 at 20 MHz and 295 K). Most remarkably, the kinetic inertness of the complex is improved to a great extent by the rigidifying effect of the diaminecyclohexane unit in the ligand skeleton: the half-live of dissociation calculated for physiological conditions is 6 orders of magnitude higher for [Gd(cddadpa)]- (t1/2=1.49x105 h) than for [Gd(octapa)]-. As compared to non-macrocyclic MRI contrast agents approved for clinical use ([Gd(dtpa-bma)], [Gd(dtpa-bmea)], [Gd(dtpa)]2- and [Gd(bopta)]2-), the kinetic inertness of this novel chelate is superior by 2-3 orders of magnitude, and it is the highest among all linear Gd3+ chelates known so far.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
gadolinium
NMR imaging
contrast agents
coordination compounds
lanthanides
Megjelenés:Chemistry-A European Journal. - 22 : 3 (2016), p. 896-901. -
További szerzők:Regueiro-Figueroa, Martín Nagy Viktória (1989-) (vegyész és kémia tanár) Garda Zoltán (1989-) (vegyész) Garai Tamás Kálmán Ferenc K. (1978-) (vegyész) Esteban-Gómez, David Tóth Éva (1967-) (koordinációs kémia) Platas-Iglesias, Carlos
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4.

001-es BibID:BIBFORM038091
Első szerző:Tircsó Gyula (vegyész, kémia tanár)
Cím:Lanthanide Complexes Formed with the Tri- and Tetraacetate Derivatives of Bis(aminomethyl)phosphinic Acid : Equilibrium, Kinetic and NMR Spectroscopic Studies / Gyula Tircsó, Ferenc K. Kálmán, Róbert Pál, István Bányai, Tamás R. Varga, Róbert Király, István Lázár, Laurent Québatte, André E. Merbach, Éva Tóth, Ernő Brücher
Dátum:2012
ISSN:1434-1948
Megjegyzések:The lanthanide(III) complexes formed with the tri- and tetraacetate derivatives of bis(aminomethyl)phosphinic acid, L1 and L2, respectively, have been studied by pH potentiometry, spectrophotometry and 1H and 17O NMR spectroscopy. L1 forms [Ln(L1)]?, [Ln(L1)2]4?, protonated [Ln(HL1)] and Ln(H2L1)]+, and [Ln(L1)(OH)]2? hydroxido complexes. Heptadentate L2 forms [Ln(L2)]2? and protonated [Ln(HL2)]? and [Ln(H2L2)] complexes in solution and it shows a strong propensity to form [Ln2(L2)]+ dinuclear complexes, which has not been observed previously. The stability constants (log?KLnL) of the complexes increase in the order [Ln(L1)]? < [Ln(L2)]2? following the order of increasing number of acetate pendants attached to the bis(aminomethyl)phosphinic acid (BAP) backbone. Within the LnIII series, the log?KLnL values increase from La3+ to Gd3+ and remain practically constant for the heavier lanthanides. Despite the lower basicity, the ligands that contain a phosphinate group generally form similar (L1) or more stable (L2) Ln3+ complexes than the structurally similar N-benzylethylenediamine-N,N·,N·-triacetic acid (L3) and propylenediamine-N,N,N·,N·-tetraacetic acid (L4), respectively. This indicates that the hard phosphinate group may be coordinated to the Ln3+ ions in the complexes, whereas the larger negative charge of the BAP derivatives may also have an extra stabilizing effect. The kinetic inertness of [Ln(L1)] and [Ln(L2)] is lower than that of similar [Ln(EDTA)]? (EDTA = ethylenediamine-N,N,N·,N·-tetraacetic acid), but the rate constants that characterize the dissociation of [Ln(L2)]2? are at least two orders of magnitude lower than those obtained for [Ln(L4)]?. Variable-temperature 17O transverse and longitudinal relaxation rates and NMR spectroscopic chemical shifts have been measured to assess the water exchange and rotational dynamics of [Gd(L2)]. The chemical shifts evidenced monohydration of the complex. The water exchange rate, kex298 = (2.7???0.4)???107 s?1 is about ten times higher than that of [Ln(DTPA)]2? (DTPA = diethylenetriamine-N,N,N·,Nı,Nı-pentaacetic acid). The rotational correlation time, ?RO298 = 270???30 ps, is long considering the small size of the chelate, which points to aggregation in aqueous solution, in accordance with the high value of the proton relaxivity measured.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Lanthanides
Imaging agents
Kinetics
Protonation constants
Stability constants
Water exchange rate
Molekulatudomány
Megjelenés:European Journal Of Inorganic Chemistry. - 12 (2012), p. 2062-2073. -
További szerzők:Kálmán Ferenc K. (1978-) (vegyész) Pál Róbert Bányai István (1953-) (vegyész) Varga Tamás Róbert (1967-) (kémia tanár) Király Róbert (1947-) (vegyész) Lázár István (1959-) (vegyész) Québatte, Laurent Merbach, André E. Tóth Éva (1967-) (koordinációs kémia) Brücher Ernő (1935-) (vegyész)
Pályázati támogatás:TÁMOP-4.2.1/B-09/1/KONV-2010-0007
TÁMOP
Bimodális kontrasztanyagok tervezése, előállítása és komplexeik fizikai-kémiai tulajdonságaik jellemzése
TÁMOP-4.2.2./B-10/1-2010-0024
TÁMOP
K84291
OTKA
PD83253
OTKA
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Intézményi repozitóriumban (DEA) tárolt változat
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5.

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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Intézményi repozitóriumban (DEA) tárolt változat
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