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1.

001-es BibID:BIBFORM016483
Első szerző:Purgel Mihály (vegyész)
Cím:An NMR and DFT Investigation on the Conformational Properties of Lanthanide(III) 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetate Analogues Containing Methylenephosphonate Pendant Arms / Mihály Purgel, Zsolt Baranyai, Andrés de Blas, Teresa Rodríguez-Blas, István Bányai, Carlos Platas-Iglesias, Imre Tóth
Dátum:2010
ISSN:0020-1669
Megjegyzések:The conformational properties of lanthanide(III) complexes with the mono- and biphosphonate analogues of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) are investigated by means of density functional theory (DFT) calculations and NMR spectroscopy Geometry optimizations performed at the B3LYP/6-31G(d) level and using a 46 + 4f(n) effective core potential for lanthanides provide two energy minima corresponding to the square-antiprismatic (SAP) and twisted square-antiprismatic (TSAP) geometries Our calculations give relative free energies between the SAP and TSAP isomers in fairly good agreement with the experimental values The SAP isomer presents the highest binding energy of the ligand to the metal ion, which further increases with respect to that of the TSAP isomer across the lanthanide senes as the charge density of the metal ion increases The stabilization of the TSAR isomer upon substitution of the acetate arms of DOTA by methylenephosphonate ones is attributed to the higher steric demand of the phosphonate groups and the higher strain of the ligand in the SAP isomer A H-1 NMR band-shape analysis performed on the [Ln(DO(2)A(2)P)](3-) (Ln = La and Lu) complexes provided the activation parameters for enantiomerization of the TSAP form of the complexes. The TSAP isomerization process was also investigated by using DFT calculations on the [Lu(DOTA)](-) and [Ln(DO(2)A(2)P)](3-) (Ln = La and Lu) systems. Our results confirm that enantiomerization requires both rotation of the pendant arms and inversion of the four five-membered chelate rings formed upon coordination of the macrocyclic unit According to our calculations, the arm rotation pathway in [Lu(DOTA)](-) is a one-step process involving the simultaneous rotation of the four acetate arms, while in the DO(2)A(2)P analogue, the arm-rotation process is a multistep path involving the stepwise rotation of each of the four pendant arms The calculated activation free energies are in reasonably good agreement with the experimental data A comparison of the experimental C-13 NMR shifts of [Ln(DO(2)A(2)P)](3-) (Ln=La and Lu) complexes and those calculated by using the GIAO method confirms that the major isomer observed in solution for these complexes corresponds to the TSAP isomer.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
mri contrast agents
water exchange-rate
macrocyclic polyamino
carboxylates
density-functional theory
x-ray-diffraction
aqueous-solution
ab-initio
coordination sphere
gadolinium complexes
crystal-structure
Megjelenés:Journal of Biological Inorganic Chemistry. - 49 : 9 (2010), p. 4370-4382. -
További szerzők:Baranyai Zsolt (1977-) (vegyész) de Blas, Andrés Rodríguez-Blas, Teresa Bányai István (1953-) (vegyész) Platas-Iglesias, Carlos Tóth Imre (1950-) (vegyész)
Internet cím:DOI
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2.

001-es BibID:BIBFORM057619
Első szerző:Regueiro-Figueroa, Martín
Cím:Highly Stable Complexes of Divalent Metal Ions (Mg(II), Ca(II) , Cu(II), Zn(II), Cd(II), and Pb(II) with a Dota-Like Ligand Containing a Picolinate Pendant / Martín Regueiro-Figueroa, Erika Ruscsák, Laura Fra, Gyula Tircsó, Imre Tóth, Andrés de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias, David Esteban-Gómez
Dátum:2014
ISSN:1434-1948
Megjegyzések:The stability constants of complexes of the macrocyclic liganddo3a-pic4? (H4do3a-pic = 2,2 ,2 -{10-[(6-carboxypyridin-2-yl)methyl]-1,4,7,10-tetraazacyclododecane-1,4,7-triyl}triacetic acid) with several divalent metal ions (Pb2+,Cd2+, Zn2+, Cu2+, Ca2+, and Mg2+) have been determined byusing pH-potentiometric titrations (I = 0.1 M KCl, 25 ?C). Thestability of these complexes follows the trend Cu2+ Cd2+?Pb2+?Zn2+ Ca2+ Mg2+. A particularly high stabilityconstant has been determined for the Cu2+ complex[logKCuL = 23.20(4)]. Analysis of the titration curves indicatethe presence of protonated forms of the complexes in solution,with protonation constants of logKM(HxL) = 6.9?2.0 (x =1, 2, or 3). The structure of the complexes in solution hasbeen investigated by using 1H and 13C NMR spectroscopyand DFT calculations performed in aqueous solution at theTPSSh/6-31G(d) level. In the case of the Pb2+ and Cd2+ complexes,relativistic effects were considered with the use ofrelativistic effective core potentials. Calculations show thatthe complexes with the largest metal ions (Pb2+ and Ca2+)are nine-coordinate, with their coordination polyhedra beingbest described as capped twisted square antiprisms. TheCd2+ and Mg2+ complexes are seven-coordinate, with themetal ions being bound to the four nitrogen atoms of the cyclenunit and the three acetate pendant arms. Finally, in theCu2+ and Zn2+ complexes, the metal ions are six-coordinated,with the metal ions being asymmetrically placed inside themacrocyclic cavity of the ligand, and the coordination polyhedracan be described as an octahedron and a trigonalprism, respectively.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Highly Stable Complexes
DOTA-like ligands
Picolinate Pendant
Megjelenés:European Journal Of Inorganic Chemistry. - 2014 : 36 (2014), p. 6165-6173. -
További szerzők:Ruscsák Erika (1989-) (vegyész) Fra, Laura Tircsó Gyula (1977-) (vegyész, kémia tanár) Tóth Imre (1950-) (vegyész) de Blas, Andrés Rodríguez-Blas, Teresa Platas-Iglesias, Carlos Esteban-Gómez, David
Pályázati támogatás:Xunta de Galicia (CN 2012/011), (EM 2012/ 088)
Egyéb
Centro de Supercomputación de Galicia (CESGA)
Egyéb
K-84291
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0043
TÁMOP
János Bolyai Research Scholarship of the Hungarian Academy of Sciences
Egyéb
COST TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging-Guided Drug Delivery" Action.
Egyéb
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3.

001-es BibID:BIBFORM018843
Első szerző:Regueiro-Figueroa, Martín
Cím:Lanthanide dota-like Complexes Containing a Picolinate Pendant: Structural Entry for the Design of LnIII-Based Luminescent Probes / Martín Regueiro-Figueroa, Bachir Bensenane, Erika Ruscsák, David Esteban-Gómez, Loïc J. Charbonnière, Gyula Tircsó, Imre Tóth, Andrès de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias
Dátum:2011
ISSN:0020-1669
Megjegyzések:In this contribution we present two ligands based on a do3a platform containing a picolinate group attached to the fourth nitrogen atom of the cyclen unit, which are designed for stable lanthanide complexation in aqueous solutions. Potentiometric measurements reveal that the thermodynamic stability of the complexes is very high (log K = 21.2?23.5), being comparable to that of the dota analogues. Luminescence lifetime measurements performed on solutions of the EuIII and TbIII complexes indicate that the complexes are nine coordinate with no inner-sphere water molecules. A combination of density functional theory (DFT) calculations and NMR measurements shows that for the complexes of the heaviest lanthanides there is a major isomer in solution consisting of the enantiomeric pair ?(????) and ?(????), which provides square antiprismatic coordination (SAP) around the metal ion. Analysis of the YbIII-induced paramagnetic shifts unambiguously confirms that these complexes have SAP coordination in aqueous solution. For the light lanthanide ions however both the SAP and twisted-square antiprismatic (TSAP) isomers are present in solution. Inversion of the cyclen ring appears to be the rate-determining step for the ?(????) ? ?(????) enantiomerization process observed in the LuIII complexes. The energy barriers obtained from NMR measurements for this dynamic process are in excellent agreement with those predicted by DFT calculations. The energy barriers calculated for the arm-rotation process are considerably lower than those obtained for the ring-inversion path. Kinetic studies show that replacement of an acetate arm of dota by a picolinate pendant results in a 3-fold increase in the formation rate of the corresponding EuIII complexes and a significant increase of the rates of acid-catalyzed dissociation of the complexes. However, these rates are 1?2 orders of magnitude lower than those of do3a analogues, which shows that the complexes reported herein are remarkably inert with respect to metal ion dissociation.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Molekulatudomány
Megjelenés:Inorganic Chemistry. - 50 : 9 (2011), p. 4125-4141. -
További szerzők:Bensenane, Bachir Ruscsák Erika (1989-) (vegyész) Esteban-Gómez, David Charbonnière, Loïc J. Tircsó Gyula (1977-) (vegyész, kémia tanár) Tóth Imre (1950-) (vegyész) Blas, Andrès de Rodríguez-Blas, Teresa Platas-Iglesias, Carlos
Pályázati támogatás:TÁMOP-4.2.1/B-09/1/KONV-2010-0007
TÁMOP
Ritkaföldfém munkacsoport
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4.

001-es BibID:BIBFORM067299
035-os BibID:(WoS)000371753500032 (Scopus)84960430930
Első szerző:Rodríguez-Rodríguez, Aurora
Cím:Complexation of Ln3+ Ions with Cyclam Dipicolinates: A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties / Aurora Rodríguez-Rodríguez, Martín Regueiro-Figueroa, David Esteban-Gómez, Raphaël Tripier, Gyula Tircsó, Ferenc Krisztián Kálmán, Attila Csaba Bényei, Imre Tóth, Andrés de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias
Dátum:2016
ISSN:0020-1669
Megjegyzések:The coordination properties toward the lanthanide ions of two macrocyclic ligands based on a cyclam platform containing picolinate pendant arms have been investigated. The synthesis of the ligands was achieved by using the well-known bis-aminal chemistry. One of the cyclam derivatives (cb-tedpa2?) is reinforced with a cross-bridge unit, which results in exceptionally inert [Ln(cb-tedpa)]+ complexes. The X-ray structures of the [La(cb-tedpa)Cl], [Gd(cb-tedpa)]+, and [Lu(Me2tedpa)]+ complexes indicate octadentate binding of the ligands to the metal ions. The analysis of the Yb3+-induced shifts in [Yb(Me2tedpa)]+ indicates that this complex presents a solution structure very similar to that observed in the solid state for the Lu3+ analogue. The X-ray structures of [La(H2Me2tedpa)2]3+ and [Yb(H2Me2tedpa)2]3+ complexes confirm the exocyclic coordination of the metal ions, which gives rise to coordination polymers with the metal coordination environment being fulfilled by oxygen atoms of the picolinate groups and water molecules. The X-ray structure of [Gd(Hcb-tedpa)2]+ also indicates exocyclic coordination that in this case results in a discrete structure with an eight-coordinated metal ion. The nonreinforced complexes [Ln(Me2tedpa)]+ were prepared and isolated as chloride salts in nonaqueous media. However, these complexes were found to undergo dissociation in aqueous solution, except in the case of the complexes with the smallest Ln3+ ions (Ln3+ = Yb3+ and Lu3+). A DFT investigation shows that the increased stability of the [Ln(Me2tedpa)]+ complexes in solution across the lanthanide series is the result of an increased binding energy of the ligand due to the increased charge density of the Ln3+ ion.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
lanthanide
complex
cross-bridged
equilibrium
kinetic
cyclam
Megjelenés:Inorganic Chemistry. - 55 : 5 (2016), p. 2227-2239. -
További szerzők:Regueiro-Figueroa, Martín Esteban-Gómez, David Tripier, Raphaël Tircsó Gyula (1977-) (vegyész, kémia tanár) Kálmán Ferenc K. (1978-) (vegyész) Bényei Attila (1962-) (vegyész) Tóth Imre (1950-) (vegyész) Blas, Andrès de Rodríguez-Blas, Teresa Platas-Iglesias, Carlos
Pályázati támogatás:OTKA-84291
OTKA
OTKA-109029
OTKA
COST CM1006 "European F-Element Network (EuFen)"
Egyéb
COST TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging- Guided Drug Delivery"
Egyéb
Bolyai János Kutatási Ösztöndíj
MTA
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DOI
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5.

001-es BibID:BIBFORM057620
Első szerző:Rodríguez-Rodríguez, Aurora
Cím:Lanthanide(III) Complexes with a Reinforced Cyclam Ligand Show Unprecedented Kinetic Inertness / Aurora Rodríguez-Rodríguez, David Esteban-Gómez, Raphaël Tripier, Gyula Tircsó, Zoltán Garda, Imre Tóth, Andrés de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias
Dátum:2014
ISSN:0002-7863
Megjegyzések:Lanthanide(III) complexes of a cross-bridged cyclam derivative containing two picolinate pendant arms are kinetically inert in very harsh conditions such as 2 M HCl, with no dissociation being observed for at least 5 months. Importantly, the [Ln(dota)] complexes, which are recognized to be extremely inert, dissociate under these conditions with lifetimes in the range ca. 1 minute to 12 hours depending upon the Ln3+ ion. X-ray diffraction studies reveal octadentate binding of the ligand to the metal ion in the [Eu(cb-tedpa)]+ complex, while 1H and 13C NMR experiments in D2O point to the presence of a single diastereoisomer in solution with a very rigid structure. The structure of the complexes in the solid state is retained in solution, as demonstrated by the analysis of the Yb3+-induced paramagnetic shifts.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Lanthanide(III) Complexes
Reinforced Cyclam Ligand
kinetics inertness
picolinates
Megjelenés:Journal Of The American Chemical Society. - 136 : 52 (2014), p. 17954-17957. -
További szerzők:Esteban-Gómez, David Tripier, Raphaël Tircsó Gyula (1977-) (vegyész, kémia tanár) Garda Zoltán (1989-) (vegyész) Tóth Imre (1950-) (vegyész) de Blas, Andrés Rodríguez-Blas, Teresa Platas-Iglesias, Carlos
Pályázati támogatás:Ministerio de Educación y Ciencia (MEC, CTQ2009-10721), Fondo Europeo de Desarrollo Regional (FEDER, CTQ2009-10721) and Xunta de Galicia (CN 2012/011) for generous financial support and Centro de Supercomputación de Galicia (CESGA)
Egyéb
COST CM1006 "European F-Element Network (EuFen)
Egyéb
COST TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging-Guided Drug Delivery"
Egyéb
János Bólyai Research Scholarship of the Hungarian Academy of Sciences
MTA
K-84291
OTKA
K-109029
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0043
TÁMOP
Internet cím:Szerző által megadott URL
DOI
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