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1.

001-es BibID:bibEBI00020529
Első szerző:Antal Károly
Cím:On the effect of cyanide ion on the reaction of pentacyanonitrosylferrate(2-) with cysteine / Károly Antal, István Bányai, Mihály T. Beck
Dátum:1985
ISSN:0300-9246
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal of the Chemical Society. Dalton Transactions. - 1985 : 6 (1985), p. 1191-1193. -
További szerzők:Bányai István (1953-) (vegyész) Beck Mihály (1929-2017) (kémikus)
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2.

001-es BibID:BIBFORM016458
Első szerző:Budimir, Ana
Cím:Water exchange rates of water-soluble manganese(III) porphyrins of therapeutical potential / Ana Budimir, József Kalmár, István Fábián, Gábor Lente, István Bányai, Ines Batinić-Haberle, Mladen Biruš
Dátum:2010
ISSN:1477-9226
Megjegyzések:The activation parameters and the rate constants of the water-exchange reactions of (MnTE)-T-III-2-PyP5+ (meso-tetrakis(N-ethylpyridinium-2-yl) porphyrin) as cationic, Mn(III)TnHex-2-PyP5+ (meso-tetrakis(N-n-hexylpyridinium-2-yl) porphyrin) as sterically shielded cationic, and (MnTSPP3-)-T-III (meso-tetrakis(4-sulfonatophenyl) porphyrin) as anionic manganese(III) porphyrins were determined from the temperature dependence of O-17 NMR relaxation rates. The rate constants at 298 K were obtained as 4.12 x 10(6) s(-1), 5.73 x 10(6) s(-1), and 2.74 x 10(7) s(-1), respectively. On the basis of the determined entropies of activation, an interchange-dissociative mechanism (I-d) was proposed for the cationic complexes (Delta double dagger S = similar to 0 J mol(-1) K-1) whereas a limiting dissociative mechanism (D) was proposed for (MnTSPP3-)-T-III complex (Delta S double dagger = + 79 J mol(-1) K-1). The obtained water exchange rate of (MnTSPP3-)-T-III corresponded well to the previously assumed value used by Koenig et al. (S. H. Koenig, R. D. Brown and M. Spiller, Magn. Reson. Med., 1987, 4, 52-260) to simulate the H-1 NMRD curves, therefore the measured value supports the theory developed for explaining the anomalous relaxivity of (MnTSPP3-)-T-III complex. A magnitude of the obtained water-exchange rate constants further confirms the suggested inner sphere electron transfer mechanism for the reactions of the two positively charged Mn(III) porphyrins with the various biologically important oxygen and nitrogen reactive species. Due to the high biological and clinical relevance of the reactions that occur at the metal site of the studied Mn(III) porphyrins, the determination of water exchange rates advanced our insight into their efficacy and mechanism of action, and in turn should impact their further development for both diagnostic (imaging) and therapeutic purposes.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
superoxide-dismutase activity
deficient escherichia-coli
nuclear
magnetic-resonance
iron(iii) porphyrins
oxidative stress
redox
modulation
contrast-media
mechanism
relaxation
complexes
Megjelenés:Dalton Transactions. - 39 (2010), p. 4405-4410. -
További szerzők:Kalmár József (1985-) (vegyész) Fábián István (1956-) (vegyész) Lente Gábor (1973-) (vegyész) Bányai István (1953-) (vegyész) Batinić-Haberle, Ines Biruš, Mladen
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3.

001-es BibID:BIBFORM084830
Első szerző:Csajbók Éva (vegyész, kémikus)
Cím:Dynamic NMR properties of DOTA ligand: variable pH and temperature 1H NMR study on [K(HxDOTA)](3-x)- species / Éva Csajbók, István Bányai, Ernő Brücher
Dátum:2004
ISSN:1477-9226
Megjegyzések:The (1)H NMR spectra of [H(x)DOTA]((4-x)-) species are reported as a function of pH and temperature in aqueous solution. The spectra show line broadening both in ligand proton signals and also in the water proton signal by titration with KOH solution. The formation of different [K(H(x)DOTA)]((3-x)-) complexes is found to be responsible for this behaviour. At high pH the usual fluxional motions, i.e. the ring inversion and the change in the acetate arms' helicity, which are also characteristic for other but inert metal-DOTA complexes, have been detected. However, because of the kinetic lability of K(+)-O and K(+)-N coordinative bonds a new type of rearrangement appears. This new motion requires breaking of coordinative bonds in the complex and can be described as a certain type of "ring slewing" around the ring C-C bonds. At low temperature (about 270 K) the ring slewing slows down and becomes negligible compared with the ring inversion and the change in the arms' helicity. These two latter processes have the same rate. When the temperature is higher (about 320 K) the ring slewing accelerates and its rate exceeds the rate of ring inversion. At this temperature the change in the acetate arms' helicity has the same rate as the ring slewing. Additionally, in the pH range 4-5 a slow intermolecular proton exchange process has been observed between the water and the dissociable protons of [K(H(x)DOTA)]((3-x)-). A water-assisted proton exchange mechanism is proposed on the basis of the activation parameters. This finding supports the previously suggested slow proton motion hypothesis for the formation of DOTA complexes.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Dalton Transactions. - 2004 : 14 (2004), p. 2152-2156. -
További szerzők:Bányai István (1953-) (vegyész) Brücher Ernő (1935-) (vegyész)
Pályázati támogatás:OTKA T035127
OTKA
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4.

001-es BibID:BIBFORM095293
Első szerző:Jászberényi Zoltán
Cím:Equilibrium and NMR studies on Gd-III, Y-III, Cu-II and Zn-II complexes of various DTPA-N,N"-bis(amide) ligands. Kinetic stabilities of the gadolinium(III) complexes / Zoltán Jászberényi, István Bányai, Ernö Brücher, Róbert Király, Kálmán Hideg, Tamás Kálai
Dátum:2006
ISSN:1477-9226
Megjegyzések:Three DTPA-derivative ligands, the non-substituted DTPA-bis(amide) (L-0), the mono-substituted DTPA-bis(n-butylamide) (L-1) and the di-substituted DTPA-bis[bis(n-butylamide)] (L-2) were synthesized. The stability constants of their Gd3+ complexes (GdL) have been determined by pH-potentiometry with the use of EDTA or DTPA as competing ligands. The endogenous Cu2+ and Zn2+ ions form ML, MHL and M2L species. For the complexes CuL0 and CuL1 the dissociation of the amide hydrogens (CuLH-1) has also been detected. The stability constants of complexes formed with Gd3+, Cu2+ and Zn2+ increase with an increase in the number of butyl substituents in the order ML0 < ML1 < ML2. NMR studies of the diamagnetic YL0 show the presence of four diastereomers formed by changing the chirality of the terminal nitrogens of their enantiomers. At 323 K, the enantiomerization process, involving the racemization of central nitrogen, falls into the fast exchange range. By the assignment and interpretation of H-1 and C-13 NMR spectra, the fractions of the diastereomers were found to be equal at pH = 5.8 for YL0. The kinetic stabilities of GdL0, GdL1 and GdL2 have been characterized by the rates of the exchange reactions occurring between the complexes and Eu3+, Cu2+ or Zn2+. The rates of reaction with Eu3+ are independent of the [Eu2+] and increase with increasing [H+], indicating the rate determining role of the proton assisted dissociation of complexes. The rates of reaction with Cu2+ and Zn2+ increase with rising metal ion concentration, which shows that the exchange can take place with direct attack of Cu2+ or Zn2+ on the complex, via the formation of a dinuclear intermediate. The rates of the proton, Cu2+ and Zn2+ assisted dissociation of Gd3+ complexes decrease with increasing number of the n-butyl substituents, which is presumably the result of steric hindrance hampering the formation or dissociation of the intermediates. The kinetic stabilities of GdL0 and GdL1 at pH = 7.4, [Cu2+] = 1 x 10(-6) M and [Zn2+] = 1 x 10(-5) M are similar to that of Gd(DTPA)(2-), while the complex GdL2 possesses a much higher kinetic stability.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Dalton Transactions. - 2006 : 8 (2006), p. 1082-1091. -
További szerzők:Bányai István (1953-) (vegyész) Brücher Ernő (1935-) (vegyész) Király Róbert (1947-) (vegyész) Hideg Kálmán Kálai Tamás
Pályázati támogatás:T 34307
OTKA
T 038364
OTKA
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5.

001-es BibID:BIBFORM090737
Első szerző:Kalmár József (vegyész)
Cím:Detailed mechanism of the autoxidation of N-hydroxyurea catalyzed by a superoxide dismutase mimic Mn(iii) porphyrin: formation of the nitrosylated Mn(ii) porphyrin as an intermediate / József Kalmár, Bernadett Biri, Gábor Lente, István Bányai, Ana Budimir, Mladen Biruš, Ines Batinić-Haberlee, István Fábiána
Dátum:2012
ISSN:1477-9226
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Dalton Transactions. - 41 : 38 (2012), p. 11875-11884. -
További szerzők:Biri Bernadett (1986-) (vegyész) Lente Gábor (1973-) (vegyész) Bányai István (1953-) (vegyész) Budimir, Ana Biruš, Mladen Batinić-Haberle, Ines Fábián István (1956-) (vegyész)
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6.

001-es BibID:BIBFORM089116
Első szerző:Sarka Lajos
Cím:Synthesis, equilibrium and NMR studies of lanthanide(III) complexes of the N-mono(methylamide) and N'-mono(methylamide) derivatives of diethylenetriamine-N,N,N',N'',N''-pentaacetic acid / Lajos Sarka, István Bányai, Ernő Brücher, Róbert Király, Johannes Platzek, Bernd Radüchel, Heribert Schmitt-Willich
Dátum:2000
ISSN:0300-9246 1364-5447
Megjegyzések:Two derivative ligands of diethylenetriamine-N,N,N',N ",N "-pentaacetic acid (H(5)DTPA; H5L1) were synthesized: the symmetric and asymmetric mono(methylamides) DTPA-N'-MA (H4L3) and DTPA-N-MA (H4L4). The protonation constants (log K-i(H)) of L-3 and L-4 were obtained by pH-potentiometric titration: 10.04, 8.41, 2.73, 1.94 and 10.18, 6.19, 3.55, 2.0, respectively. The protonation constants and the sites of protonation were interpreted on the basis of the pH dependence of the chemical shifts of the non-labile protons. The stability constants (K-LnL) of the complexes of these ligands with lanthanide(III) ions were determined by direct pH-potentiometry and competition titration. The stability constants decrease in the sequence LnL(1) > LnL(3) > LnL(4). The log K-LnL values of the complexes LnL(3) and LnL(4) increase with increasing atomic number of Ln(3+) from La to Gd, then remain roughly unchanged up to Er and subsequently decrease slightly to Lu. The H-1 and C-13 NMR spectra reveal the presence of 2 isomers for the complexes LnL(3) and 4 isomers for LnL(4) at around 0 degrees C. The AB multiplets of the acetate methylene protons demonstrate the long lifetime of the Ln(3+)-N bonds. The coupling observed between the methyl and methylene protons of the methylamide group in the 2-D COSY spectra indicates partial double bond character of the C-NMe bond.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal of the Chemical Society. Dalton Transactions. - 2000 : 20 (2000), p. 3699-3703. -
További szerzők:Bányai István (1953-) (vegyész) Brücher Ernő (1935-) (vegyész) Király Róbert (1947-) (vegyész) Platzek, Johannes Radüchel, Bernd Schmitt-Willich, Heribert
Pályázati támogatás:OTKA 23810
OTKA
OTKA T 026115
OTKA
FKFP 0448/1997
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