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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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2.

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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