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001-es BibID:	BIBFORM120545
035-os BibID:	(WoS)000302861900019 (Scopus)84859904566
Első szerző:	Forgács Attila (vegyész)
Cím:	Influence of gem-Dimethyl Substitution on the Stability, Kinetics and Relaxometric Properties of PDTA Complexes / Attila Forgács, Giovanni B. Giovenzana, Mauro Botta, Erno Brücher, Imre Tóth, Zsolt Baranyai
Dátum:	2012
ISSN:	1434-1948
Megjegyzések:	The protonation constants of DMPDTA (H4DMPDTA = 2,2-dimethylpropylenediamine-N,N,N',N'-tetraacetic acid) and the stability and protonation constants of its Ln3+ and some divalent metal complexes have been determined by pH potentiometry and spectrophotometry (Cu2+) and compared with the corresponding properties of the complexes formed with PDTA (H4PDTA = propylenediamine-N,N,N',N'-tetraacetic acid). The log?K2H value of DMPDTA is lower by 1.5 logK units than that of PDTA. The stability constants (log?KML) of the Ln3+ complexes formed with DMPDTA are lower by 1.01.5 logK units than those of PDTA. The kinetics of the transmetallation reactions of Gd(DMPDTA) and Gd(PDTA) with Cu2+ and Eu3+ have been studied by spectrophotometry. The reactions with Cu2+ and Eu3+ occur predominantly by spontaneous and proton-assisted dissociation of the Gd(DMPDTA) and Gd(PDTA) complexes. The rates of the metal-exchange reactions of Gd(DMPDTA) are significantly lower than those of Gd(PDTA). The presence of the two methyl groups on the ligand backbone increases the kinetic inertness of Gd(DMPDTA) due to the higher conformational rigidity of DMPDTA. Temperature-dependent 17O NMR spectra and 1/T1 1H nuclear magnetic relaxation dispersion profiles of the Gd3+ complexes were measured and analyzed to obtain the parameters that influence the water exchange rate and rotational dynamics.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk Lanthanides Thermodynamics Kinetics Relaxation
Megjelenés:	European Journal Of Inorganic Chemistry. - 2012 : 12 (2012), p. 2074-2086. -
További szerzők:	Giovenzana, Giovanni Battista Botta, Mauro Brücher Ernő (1935-) (vegyész) Tóth Imre (1950-) (vegyész) Baranyai Zsolt (1977-) (vegyész)
Pályázati támogatás:	K 84291 OTKA TÁMOP4.2.1./B-09/1/KONV-2010-0007 TÁMOP TÁMOP4.2.2./B-10/1-2010-0024 TÁMOP
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001-es BibID:	BIBFORM078703
Első szerző:	Vágner Adrienn (vegyész, kémikus)
Cím:	Equilibrium Thermodynamics, Formation, and Dissociation Kinetics of Trivalent Iron and Gallium Complexes of Triazacyclononane-Triphosphinate (TRAP) Chelators: Unraveling the Foundations of Highly Selective Ga-68 Labeling / Adrienn Vágner, Attila Forgács, Ernő Brücher, Imre Tóth, Alessandro Maiocchi, Alexander Wurzer, Hans-Jürgen Wester, Johannes Notni, Zsolt Baranyai
Dátum:	2018
ISSN:	2296-2646
Megjegyzések:	In order to rationalize the influence of FeIII contamination on labeling with the 68Ga eluted from 68Ge/68Ga-generator, a detailed investigation was carried out on the equilibrium properties, formation and dissociation kinetics of GaIII- and FeIII - complexes of 1,4,7-triazacyclononane-1,4,7-tris(methylene[2-carboxyethylphosphinic acid]) (H6TRAP). The stability and protonation constants of the [Fe(TRAP)]3? complex were determined by pH-potentiometry and spectrophotometry by following the competition reaction between the TRAP ligand and benzhydroxamic acid (0.15 M NaNO3, 25?C). The formation rates of [Fe(TRAP)] and [Ga(TRAP)] complexes were determined by spectrophotometry and 31P-NMR spectroscopy in the pH range 4.5? 6.5 in the presence of 5?40 fold HxTRAP(x?6) excess (x = 1 and 2, 0.15 M NaNO3, 25?C). The kinetic inertness of [Fe(TRAP)]3? and [Ga(TRAP)]3? was examined by the trans-chelation reactions with 10 to 20-fold excess of HxHBED(x?4) ligand by spectrophotometry at 25?C in 0.15 M NaCl (x = 0,1 and 2). The stability constant of [Fe(TRAP)]3? (logKFeL = 26.7) is very similar to that of [Ga(TRAP)]3? (logKGaL = 26.2). The rates of ligand exchange reaction of [Fe(TRAP)]3? and [Ga(TRAP)]3? with HxHBED(x?4) are similar. The reactions take place quite slowly via spontaneous dissociation of [M(TRAP)]3?, [M(TRAP)OH]4? and [M(TRAP)(OH)2] 5? species. Dissociation half-lives (t1/2) of [Fe(TRAP)]3? and [Ga(TRAP)]3? complexes are 1.1 ? 105 and 1.4 ? 105 h at pH = 7.4 and 25?C. The formation reactions of [Fe(TRAP)]3? and [Ga(TRAP)]3? are also slow due to the formation of the unusually stable monoprotonated [?M(HTRAP)]2? intermediates [?logKGa(HL) = 10.4 and ?logKFe(HL) = 9.9], which are much more stable than the [?Ga(HNOTA)]+ intermediate [?logKGa(HL) = 4.2]. Deprotonation and transformation of the monoprotonated [?(HTRAP)]2? intermediates into the final complex occur via OH?-assisted reactions. Rate constants (kOH) characterizing the OH?-driven deprotonation and transformation of [? Ga(HTRAP)]2? and [?Fe(HTRAP)]2? intermediates are 1.4 ? 105 M?1 s-1 and 3.4 ? 104 ?1s?1, respectively. In conclusion, the equilibrium and kinetic properties of [Fe(TRAP)] and [Ga(TRAP)] complexes are remarkably similar due to the close physico-chemical properties of FeIII and GaIII-ions. However, a slightly faster formation of [Ga(TRAP)] over [Fe(TRAP)] provides a rationale for a previously observed, selective complexation of 68GaIII in presence of excess FeIII.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban chelates gallium iron thermodynamics kinetics reaction mechanism positron emission tomography
Megjelenés:	Frontiers in Chemistry. - 6 (2018), p. 1-12. -
További szerzők:	Forgács Attila (1988-) (vegyész) Brücher Ernő (1935-) (vegyész) Tóth Imre (1950-) (vegyész) Maiocchi, Alessandro (vegyész) Wurzer, Alexander Wester, Hans J. Notni, Johannes Baranyai Zsolt (1977-) (vegyész)
Pályázati támogatás:	GINOP-2.3.3-15-2016-00004 GINOP GINOP-2.3.2-15-2016-00008 GINOP
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