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001-es BibID:	BIBFORM067445
Első szerző:	Nagy Nóra Veronika
Cím:	Copper(II) complexes of some N-substituted bis(aminomethyl)phosphinate ligands : An integrated EPR study of microspeciation and coordination modes by the two-dimensional simulation method / Nóra Veronika Nagy, Terézia Szabó-Plánka, Gyula Tircsó, Róbert Király, Zsuzsanna Árkosi, Antal Rockenbauer, Ernő Brücher
Dátum:	2004
ISSN:	0162-0134
Megjegyzések:	Copper(II) complexes of bis(aminomethyl)phosphinic acid (L1), bis(N-glycino-N-methyl)phosphinic acid (L2), bis(N-benzylglycino-N-methyl)phosphinic acid (L3), bis(l-prolino-N-methyl)phosphinic acid (L4) and bis(iminodicarboxymethyl-N-methyl)phosphinic acid (L5) were studied in aqueous solution by pH-potentiometric and electron paramagnetic resonance (EPR) spectroscopic methods. The EPR spectrum packages recorded at various ligand-to-metal concentration ratios and pH's were analyzed (after matrix rank analysis by the method of residual intensities as a complementary method) by the two-dimensional computer simulation method, which simultaneously determines the formation constants and the EPR parameters of the various (micro)species. L1 forms mono and bis complexes in different protonation states; for the other ligands, the mono complexes are always prevalent. For steric reasons, the formation of CuL is shifted to increasingly higher pH regions in the sequence L2, L3 and L4. CuLH was identified for L3, L4 and L5, and also CuLH2 for L4 and L5. Cu2L2 was found in small amounts for L3 and L4, while it predominates at pH > 4 for L5. For L5, Cu2L2H2 was also detected. For the ligands that form dimeric metal complexes in equimolar solution or at a ligand excess, Cu2L is formed at a metal ion excess. Ligation of the phosphinate O was suggested by indirect proofs in the protonated complexes of L1. For the ligands L2, L3 and L4, the copper(II) coordination in various species in different protonation states is reminiscent of that in the mono and bis complexes of simple amino acids. For the bis(aminomethyl)phosphinates, however, the cis positions of the amino groups in CuL are ensured by the structure of the ligand, and the isomers differ from each other in the (equatorial or axial) position of the second carboxylate group.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Electron paramagnetic resonance Copper(II) complexes N-Substituted bis(aminomethyl)phosphinic acids Microspeciation Coordination modes
Megjelenés:	Journal of Inorganic Biochemistry 98 : 11 (2004), p. 1655-1666. -
További szerzők:	Szabó-Plánka Terézia Tircsó Gyula (1977-) (vegyész, kémia tanár) Király Róbert Árkosi Zsuzsanna Rockenbauer, Antal Brücher Ernő (1935-) (vegyész)
Pályázati támogatás:	T-032929 OTKA T-038364 OTKA T-046953 OTKA
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001-es BibID:	BIBFORM082453
Első szerző:	Sarka Lajos
Cím:	Studies on the kinetic stabilities of the Gd3+ complexes formed with the N-mono(methylamide), N'-mono(methylamide) and N,N"-bis(methylamide) derivatives of diethylenetriamine-N,N,N',N",N"-pentaacetic acid / Lajos Sarka, László Burai, Róbert Király, László Zékány, Ernő Brücher
Dátum:	2002
ISSN:	0162-0134
Megjegyzések:	High kinetic stability is an important requirement for the Gd3+ complexes used as contrast enhancement agents in magnetic resonance imaging. The kinetic stabilities of the Gd3+ complexes formed with DTPA-N-mono(methylamide) (L3), DTPA-N'-mono(methylamide) (L2) and DTPA-bis(methylamide) (L1) are characterized by the rates of the exchange reactions with Eu3+ and the endogenous Cu2+ and Zn2+. The exchange reactions occur via the proton-assisted dissociation of the complexes and direct attack of the exchanging metal ions on the complex. On the basis of the line-shape analysis of the 1H NMR spectra of the LaL2, obtained in the pH range 2.5-3.5, we assume that for the proton-assisted dissociation of the complexes the formation of an intermediate containing a free iminodiacetate group must be followed with the rupture of the metal-central nitrogen bond. At about pH>=5, the reactions between GdL2 or GdL3 and Cu2+ or Zn2+ proceed predominantly by direct reaction of the reactants, through the formation of dinuclear intermediates. The contribution of the proton-assisted dissociation is highly important for GdL1, but its reaction with Zn2+ is significantly slower than the reactions of GdL2 and GdL3. The overall rates of dissociation of GdL1, GdL2, GdL3 and Gd(DTPA)2- through H+ (pH 7.4), Cu2+ (1x10-6 M) and Zn2+ (1x10-5 M)-assisted reactions are surprisingly very similar. Replacement of one or two carboxylates with amide groups results in significantly decreased stability constants, but has practically no effect on the kinetic stability of the Gd3+ complexes, indicating the lower reactivity of the amide groups with Cu2+ and Zn2+.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Journal of Inorganic Biochemistry. - 91 : 1 (2002), p. 320-326. -
További szerzők:	Burai László Király Róbert (1947-) (vegyész) Zékány László (1948-) (vegyész) Brücher Ernő (1935-) (vegyész)
Pályázati támogatás:	OTKA T025462 OTKA
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001-es BibID:	BIBFORM103942
035-os BibID:	(WOS)000528630900017 (Scopus)85080905990
Első szerző:	Tircsó Gyula (vegyész, kémia tanár)
Cím:	Comparison of the equilibrium, kinetic and water exchange properties of some metal ion-DOTA and DOTA-bis(amide) complexes / Gyula Tircsó, Enikő Tircsóné Benyó, Zoltán Garda, Jaspal Singh, Robert Trokowski, Ernő Brücher, A. Dean Sherry, Éva Tóth, Zoltán Kovács
Dátum:	2020
ISSN:	0162-0134 1873-3344
Megjegyzések:	The 1,7-diacetate-4,10-diacetamide substituted 1,4,7,10-tetraazacyclododecane structural unit is common to several responsive Magnetic Resonance Imaging (MRI) contrast agents (CAs). While some of these complexes (agents capable of sensing fluctuations in Zn2+, Ca2+ etc. ions) have already been tested in vivo, the detailed physico-chemical characterization of such ligands have not been fully studied. To fill this gap, we synthesized a representative member of this ligand family possessing two acetate and two n-butylacetamide pendant side-arms (DO2A2M(nBu) = 1,4,7,10-tetraazacyclodoecane-1,7-di(acetic acid)-4,10-di(N-butylacetamide)), and studied its complexation properties with some essential metal and a few lanthanide(III) (Ln(III)) ions. Our studies revealed that the ligand basicity, the stability of metal ion complexes, the trend of stability constants along the Ln(III) series, the formation rates of the Ln(III) complexes and the exchange rate of the bound water molecule in the Gd (III) complex fell between those of Ln(DOTA) - and Ln(DOTA-tetra(amide))(3+) complexes (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTAM = 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane). The only exception is the stability of Cu(DO2A2M(nBu)) which was found to be only slightly lower than that of Cu(DOTA)(2-) (log K-CuL = 19.85 vs. 21.98). This is likely reflects exclusive coordination of the negatively charged acetate donor atoms to the Cu2+ ion forming an octahedral complex with the amides remaining uncoordinated. The only anomaly observed during the study was the rates of acid assisted dissociation of the Ln(III) complexes, which occur at a rate similar to those observed for the Ln(DOTA)(-) complexes. These data indicate that even though the Ln(DO2A2M(nBu))(+) complexes have lower thermodynamic stabilities, their kinetic inertness should be sufficient for in vivo use.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény hazai lapban folyóiratcikk Coordination chemistry Complexes Physico-chemical parameters Synthesis Stability Inertness Water exchange rate
Megjelenés:	Journal of Inorganic Biochemistry. - 206 (2020), p. 1-12. -
További szerzők:	Tircsóné Benyó Enikő (1977-) (vegyész, kémia tanár) Garda Zoltán (1989-) (vegyész) Singh, Jaspal Trokowski, Robert Brücher Ernő (1935-) (vegyész) Sherry, A. Dean Tóth Éva Kovács Zoltán
Pályázati támogatás:	NKFIH-K-120224 Egyéb NKFIH-128201 Egyéb GINOP-2.3.2-15-2016-00008 GINOP
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