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, G. Tircsó, Ferenc Krisztián Kálmán, A. Bényei, Imre Tóth, Andrés De Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias

Research output: Contribution to journalArticle

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Abstract

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.

Original languageEnglish
Pages (from-to)2227-2239
Number of pages13
JournalInorganic Chemistry
Volume55
Issue number5
DOIs
Publication statusPublished - Mar 7 2016

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Complexation
Ions
Ligands
Metal ions
Lanthanoid Series Elements
metal ions
ligands
Kinetics
kinetics
X rays
ions
x rays
Charge density
Binding energy
coordination polymers
Discrete Fourier transforms
Chlorides
oxygen atoms
Polymers
platforms

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Rodríguez-Rodríguez, A., Regueiro-Figueroa, M., Esteban-Gómez, D., Tripier, R., Tircsó, G., Kálmán, F. K., ... Platas-Iglesias, C. (2016). Complexation of Ln3+ Ions with Cyclam Dipicolinates: A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties. Inorganic Chemistry, 55(5), 2227-2239. https://doi.org/10.1021/acs.inorgchem.5b02627

Complexation of Ln3+ Ions with Cyclam Dipicolinates : A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties. / Rodríguez-Rodríguez, Aurora; Regueiro-Figueroa, Martín; Esteban-Gómez, David; Tripier, Raphaël; Tircsó, G.; Kálmán, Ferenc Krisztián; Bényei, A.; Tóth, Imre; Blas, Andrés De; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos.

In: Inorganic Chemistry, Vol. 55, No. 5, 07.03.2016, p. 2227-2239.

Research output: Contribution to journalArticle

Rodríguez-Rodríguez, A, Regueiro-Figueroa, M, Esteban-Gómez, D, Tripier, R, Tircsó, G, Kálmán, FK, Bényei, A, Tóth, I, Blas, AD, Rodríguez-Blas, T & Platas-Iglesias, C 2016, 'Complexation of Ln3+ Ions with Cyclam Dipicolinates: A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties', Inorganic Chemistry, vol. 55, no. 5, pp. 2227-2239. https://doi.org/10.1021/acs.inorgchem.5b02627
Rodríguez-Rodríguez, Aurora ; Regueiro-Figueroa, Martín ; Esteban-Gómez, David ; Tripier, Raphaël ; Tircsó, G. ; Kálmán, Ferenc Krisztián ; Bényei, A. ; Tóth, Imre ; Blas, Andrés De ; Rodríguez-Blas, Teresa ; Platas-Iglesias, Carlos. / Complexation of Ln3+ Ions with Cyclam Dipicolinates : A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties. In: Inorganic Chemistry. 2016 ; Vol. 55, No. 5. pp. 2227-2239.
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