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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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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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