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1.

001-es BibID:bibKLT00100248
Első szerző:Brücher Ernő (vegyész)
Cím:Complexation properties of 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7-malonate, -7,16-bis(malonate) and -7,16-bis(α-methylacetate) / E. Brücher, B. Győri, J. Emri, S. Jakab, Z. Kovács, P. Solymosi, I. Tóth
Dátum:1995
Tárgyszavak:idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of the Chemical Society. Dalton Transactions. - 20 (1995), p. 3353-3357. -
További szerzők:Győri Béla (vegyész) Emri József (vegyész) Jakab Sándor Kovács Zoltán Solymosi Piroska Tóth Imre (1950-) (vegyész)
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2.

001-es BibID:bibEBI00008428
Első szerző:Burai László
Cím:Synthesis, potentiometry, and NMR studies of two new 1,7-disubstituted tetraazacyclododecanes and their complexes formed with lanthanide, alkaline earth metal, Mn2+, and Zn2+ ions / L. Burai, J. Ren, Z. Kovács, E. Brücher, A. D. Sherry
Dátum:1998
ISSN:0020-1669
Megjegyzések:Two new 1,7-disubstituted-1,4,7,10-tetraazacyclododecane ligands, DO2P and DO2PME, and their complexes with Mg2+, Ca2+, Sr2+, Mn2+, Zn2+ and Ln3+ were prepared and characterized by pH potentiometry. The pH titration data showed that DO2P and DO2PME both form 1:1 M:L complexes with all divalent and trivalent metal ions. Protonated complexes did not appear to form with the bis(phosphonate ester) ligand, DO2PME, but were evident for all of the metal ion?DO2P complexes. The alkaline earth metal ion?DO2P complexes formed both ML and MHL complexes while the lanthanide ion (Ln3+), Zn2+, and Mn2+ complexes of DO2P formed ML, MHL, and MH2L species. Zn2+ formed the most stable complex with both ligands. The stability (β101) of the LnDO2PME+ complexes increased by about 2 orders of magnitude along the lanthanide series (La3+ to Lu3+) while the stability of the LnDO2P- complexes over this same series increased by over 3 orders of magnitude. The bis(phosphonate) ligand, DO2P, and some of its complexes formed with Ln3+ ions were further examined by NMR spectroscopy. 1H and 31P spectra of DO2P collected as a function of pH provided evidence that the first two protonations on the ligand take place largely at the tertiary nitrogens. The similarity of the 31P chemical shifts of EuDO2P- and EuDOTP5- indicate that DO2P forms an ?in-cage" complex with Eu3+ using all four macrocyclic ring nitrogens and the two phosphonate sidearms as ligands. 17O NMR shifts of the water signal indicated that the DyDO2P- complex has two inner-sphere coordinated water molecules. In the presence of excess of DO2P, a 1:2 metal:ligand, LnDO2P(HDO2P)4-, complex forms with the second ligand interacting only weakly with the coordination sites left vacant by the first DO2P. Both water proton relaxivity data for GdDO2P- and 31P NMR spectra of EuDO2P- provide evidence for formation of an ?out-of-cage" LnH2DO2P+ complex at low pH values (<6.5) in which the two phosphonate groups of DO2P are only involved in bonding with the lanthanide cation.
Tárgyszavak:idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Inorganic Chemistry. - 37 : 1 (1998), p. 69-75. -
További szerzők:Ren, Jimin Kovács Zoltán Brücher Ernő (1935-) (vegyész) Sherry, A. Dean
Internet cím:DOI
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3.

001-es BibID:BIBFORM076212
Első szerző:Do, Quyen N. (vegyész)
Cím:General Synthetic and Physical Methods / Quyen N. Do, James S. Ratnakar, Zoltán Kovács, Gyula Tircsó, Ferenc Krisztián Kálmán, Zsolt Baranyai, Ernő Brücher, Imre Tóth
Dátum:2017
Megjegyzések:Contrast agents for magnetic resonance imaging (MRI) currently used and approved by the Food and Drug Administration (FDA) of the United States of America are GdIII-based. Yet, GdIII complexes are only one class of contrast agents for MRI. The fundamentals described in this chapter are intended to assist with the design of future imaging agents for MRI. Ligands affect not only relaxivity but also thermodynamic stability and kinetic inertness of GdIII complexes, which in turn affect the safety profiles of contrast agents. Divided into four sections, this chapter describes syntheses and characterization of ligands and metal complexes as well as the determination of the stability and lability of metal complexes.
ISBN:978-1-78262-447-9
Tárgyszavak:Természettudományok Kémiai tudományok könyvfejezet
Megjelenés:Contrast Agents for MRI: Experimental Methods / ed. Valérie C Pierre, Matthew J Allen. - p. 1-120. -
További szerzők:Ratnakar, James S. Kovács Zoltán Tircsó Gyula (1977-) (vegyész, kémia tanár) Kálmán Ferenc K. (1978-) (vegyész) Baranyai Zsolt (1977-) (vegyész) Brücher Ernő (1935-) (vegyész) Tóth Imre (1950-) (vegyész)
Pályázati támogatás:GINOP-2.3.2-15-2016-00008
GINOP
OTKA-120224
OTKA
Bolyai János Kutatási Ösztöndíj
Egyéb
COST CA15209
Egyéb
Le Studium - Loire Valley Institute for Advanced Studies
Egyéb
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4.

001-es BibID:BIBFORM006198
Első szerző:Kálmán Ferenc K. (vegyész)
Cím:Synthesis, potentiometric, kinetic, and NMR studies of 1,4,7,10-tetraazacyclododecane-1,7-bis(acetic acid)-4,10-bis(methylenephosphonic acid) (DO2A2P) and its complexes with Ca(II), Cu(II), Zn(II) and lanthanide(III) ions / Kalman, F. K., Baranyai, Z., Toth, I., Banyai, I., Kiraly, R., Brucher, E., Aime, S., Sun, X., Sherry, A. D., Kovacs, Z.
Dátum:2008
ISSN:0020-1669
Megjegyzések:A cyclen-based ligand containing trans-acetate and trans-methylenephosphonate pendant groups, H(6)DO2A2P, was synthesized and its protonation constants (12.6, 11.43, 5.95, 6.15, 2.88, and 2.77) were determined by pH-potentiometry and H-1 NMR spectroscopy. The first two protonations were shown to occur at the two macrocyclic ring N-CH2-PO32- nitrogens while the third and fourth protonations occur at the two phosphonate groups. In parallel with protonation of the two -PO32- groups, the protons from the NH+-CH2-PO32- are transferred to the N-CH2-COO- nitrogens. The stability constants of the Ca2+, Cu2+, and Zn2+ (ML, MHL, MH2L, and M2L) complexes were determined by direct pH-potentiometry. Lanthanide(III) ions (Ln(3+)) form similar species, but the formation of complexes is slow; so, "out-of-cell" pH-potentiometry (La3+, Eu3+, Gd3+, Y3+) and competitive spectrophotometry with Cu(II) ion (Lu3+) were used to determine the stability constants. By comparing the log K-ML values with those of the corresponding DOTA (H(4)DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and DOTP (H8DOTP = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid) complexes, the order DOTA < DO2A2P < DOTP was found for all the metal ion complexes examined here with the exception of the Ca2+ complexes, for which the order is reversed. The relaxivity of Gd(DO2A2P) decreases between pH 2 and 7 but remains constant in the pH range of 7 < pH < 12 (r(1) = 3.6 mM(-1) s(-1)). The linewiths of the O-17 NMR signals of water in the absence and presence of Gd(DO2A2P) (at pH = 3.45 and 8.5) between 274 and 350 K are practically the same, characteristic of a q = 0 complex. Detailed kinetic studies of the Ce3+ and Gd3+ complexes with DO2A2P showed that complex formation is slow and involves a high stability diprotonated intermediate Ln(H(2)DO2A2P)*. Rearrangement of the diprotonated intermediate into the final complex is an OH- assisted process but, unlike formation of Ln(DOTA) complexes, rearrangement of Ln(H(2)DO2A2P)* also takes place spontaneously likely as a result of transfer of one of the protons from a ring nitrogen to a phosphonate group. The order of the OH- assisted formation rates of complexes is DOTA > DO2A2P > DOTP while the order of the proton assisted dissociation rates of the Gd3+ complexes is reversed, DOTP > DO2A2P > DOTA. H-1 and C-13 NMR spectra of Eu(DO2A2P) and Lu(DO2A2P) were assigned using two-dimensional correlation spectroscopy (2D COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear chemical shift correlation (HETCOR), and exchange spectroscopy (EXSY) NMR methods. Two sets of H-1 NMR signals were observed for Eu(DO2A2P) characteristic of the presence of two coordination isomers in solution, a twisted square antiprism (TSAP) and a square antiprism (SAP), in the ratio of 93% and 7%, respectively. Line shape analysis of the H-1 NMR spectra of Lu(DO2A2P) gave lower activation parameters compared to La(DOTP) for interconversion between coordination isomers. This indicates that the Ln(DO2A2P) complexes are less rigid probably due to the different size and spatial requireents of the carboxylate and phosphonate groups.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Inorganic Chemistry. - 47 : 9 (2008), p. 3851-3862. -
További szerzők:Baranyai Zsolt (1977-) (vegyész) Tóth Imre (1950-) (vegyész) Bányai István (1953-) (vegyész) Király Róbert Brücher Ernő (1935-) (vegyész) Aime, Silvio Sun, Xiankai Sherry, A. Dean Kovács Zoltán
Internet cím:elektronikus változat
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5.

001-es BibID:BIBFORM087718
Első szerző:Szilágyi Erika
Cím:Equilibria and formation kinetics of some cyclen derivative complexes of lanthanides / Erika Szilágyi, Éva Tóth, Zoltán Kovács, Johannes Platzek, Bernd Radüchel, Ernö Brücher
Dátum:2000
ISSN:0020-1693
Megjegyzések:The kinetics of the formation reactions between the lanthanide(III) ions Ce 3+, Eu 3+ and Yb 3+ and four cyclen derivative ligands, DO3A-B, DO3A-ME, DO2A and DO2A-2B, were studied by spectrophotometry and a stopped-flow method at 25?C in 1.0 M KCl solutions. The reactions were found to be of first order, which was interpreted in terms of the formation of a diprotonated intermediate, Ln(H 2L) +. The formation of products occurs via deprotonation and rearrangement of the intermediate, characterised by the rate constant, k r. The rate law obtained, k r= k OH[OH ?], is similar to those obtained for the formation reactions of DOTA and DOTA derivative complexes. The rate constants, k OH, decrease with decrease in the number of charged carboxylate functional groups in the ligands; the lowest rates were found for the formation of the DO2A complexes. The formation rates increase significantly from Ce 3+ to Yb 3+. The direct proportionality between the formation rates and [H +] ?1 was interpreted by assuming the equilibrium formation of a monoprotonated intermediate, Ln(HL), which undergoes deprotonation in a slow, rate-determining step. The validity of general base catalysis was detected in the formation reactions, which supports the assumption of the rate-controlling role of deprotonation of the monoprotonated intermediate. The protonation constants of the ligands DO3A-ME and DO2A-2B and the stability constants of their complexes were also determined. The ligand DO2A forms the usual complexes Ln(DO2A) + and the unusual species Ln(DO2A) 2 ? . In the complexes Ln(DO2A) 2 ? , the two ligands exhibit different coordination modes which were demonstrated by 1H NMR spectroscopy.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Stability constants
Lanthanide complexes
Cyclen complexes
Megjelenés:Inorganica Chimica Acta. - 298 : 2 (2000), p. 226-234. -
További szerzők:Tóth Éva (1960-) (kémikus) Kovács Zoltán Platzek, Johannes Radüchel, Bernd Brücher Ernő (1935-) (vegyész)
Pályázati támogatás:T 025462
OTKA
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6.

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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7.

001-es BibID:bibKLT00129073
Első szerző:Varga L. P.
Cím:Mobilization of radioactive strontium from mouse and rat using dicarboxylic acid derivatives of cryptand-(2.2) / L. P. Varga, L. B. Sztanyik, É. Rónai, K. Bodó, E. Brücher, B. Győri, J. Emri, Z. Kovács
Dátum:1994
Tárgyszavak:idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:International Journal of Radiation Biology & Related Studies in Physics , Chemistry & Medicine, 66 : 4 (1994), p. 399-405. -
További szerzők:Sztanyik L. B. Rónai É. Bodó K. Brücher Ernő (1935-) (vegyész) Győri Béla (vegyész) Emri József (vegyész) Kovács Zoltán
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