AMPED: a new platform for picolinate based luminescent lanthanide chelates

Guanci, Claudia; Giovenzana, Giovanni B.; Lattuada, Luciano; Platas‐Iglesias, Carlos; Charbonnière, Loı̈c J.

doi:10.1039/c5dt00077g

Cited by 18 publications

(22 citation statements)

References 79 publications

(30 reference statements)

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“…Finally, the luminescence quantum yields were determined to be, respectively, 0.10, 0.10, and 0.08, which are very similar to reported data for Eu‐based picolinate complexes that lack inner sphere water molecules , . Although the value obtained for the trinuclear complex is a little bit smaller than for the other two, the observed difference cannot be considered as significant regarding the 15 % absolute error on these determinations.…”

Section: Resultssupporting

confidence: 78%

Spectroscopic Properties of a Family of Mono‐ to Trinuclear Lanthanide Complexes

Esteban‐Gómez

Platas‐Iglesias

et al. 2017

Eur J Inorg Chem

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International audienceA series of mono-, di-, and trinuclear complexes of Eu and Tb was designed to study the influence of the number of Ln emitting centers on the luminescence properties of discrete polynuclear complexes. The complexes are based on a cyclen scaffold, functionalized by two picolinic acid pendant arms. These coordinating units are separated by a 1,3-dimethylbenzene spacer for the dinuclear complex and a 1,3,5-trimethylbenzene bridge in the case of the trinuclear complex. The synthesis and characterization of the ligands are presented, together with the preparation and spectroscopic characterization of the complexes. The luminescence properties of the complexes were determined by UV/Vis absorption spectroscopy and steady-state and time-resolved luminescence spectroscopy in buffered aqueous solutions. Comparison of the electronic absorption spectra showed that the absorption properties can almost be considered as extensive parameters within experimental error, as expected for electronically non-conjugated systems. A small drop of both the excited state luminescence lifetimes and the luminescence quantum yields was observed for the trinuclear complexes in the case of Tb. To understand this behavior, theoretical HF (Hartree-Fock) calculations were performed for the three complexes. Models indicate that the average intermetallic distance in the dinuclear complex is almost the same as in the trinuclear one, disfavoring a possible distance dependence of the observed phenomena

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Section: Resultssupporting

confidence: 78%

Spectroscopic Properties of a Family of Mono‐ to Trinuclear Lanthanide Complexes

Esteban‐Gómez

Platas‐Iglesias

et al. 2017

Eur J Inorg Chem

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“…Upon excitation into the ligand absorption bands, all complexes (Ln = Eu, Tb and Yb) display the characteristic emission pattern of the f–f Ln emission bands in the green ( 5 D 4 → 7 F J , transitions of Tb with J = 6 to 3), red ( 5 D 0 → 7 F J , transitions of Eu with J = 0 to 4) and NIR ( 2 F 5/2 → 2 F 7/2 , transition of Yb) regions (Figure ). The observed overall luminescence quantum yields are modest for all complexes and almost half of those generally observed for luminescent complexes based on carboxylated pyridine , . All luminescence decay profile could be nicely fitted with mono‐exponential components, pointing to single species in solutions or to different species being in rapid kinetic equilibrium.…”

Section: Resultsmentioning

confidence: 79%

Phosphonated Podand Type Ligand for the Complexation of Lanthanide CationsPhosphonated Podand Type Ligand for the Complexation of Lanthanide Cations

et al. 2019

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A new tripodal ligand, based on a central nitrogen atom tris‐functionalized with 6‐methylene‐2‐pyridyl phosphonic acid was synthesized and characterized, in particular by its X‐ray crystal structure. The coordination behaviour of the tripod with lanthanide cations in aqueous solutions was studied by means of UV/Vis electronic absorption spectroscopy and steady‐state and time‐resolved luminescence spectroscopy, revealing the formation of a [LnL] complex followed by polynuclear species with 2:1 and 3:1 metal/ligand stoichiometries. The [LnL] complexes (Ln = Eu, Tb and Yb) were isolated and characterized and the solid‐state structure of the Eu complex was determined by X‐ray diffraction analysis on monocrystals, revealing the observation of dimeric species, in which the Ln3+ cations are firmly held in the cavity formed by the three pyridylphosphonate arms, the coordination of the cations being completed by a water molecule and a phosphonate function of the second complex, allowing for the formation of the dimers, which are further stabilized by π–π stacking interactions between one pyridyl unit of each adjacent monomer. The spectroscopic properties of the complexes in aqueous solutions were studied, showing an impressive 16 µs excited state lifetime for the Yb complex in D2O, despite the presence of a water molecule in the first coordination sphere.

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“…a Estimated error ± 10%. Estimated Error ± 15%.The overall luminescence quantum yield of the [EuL1]and [TbL1]complexes are rather weak, being almost half of the values obtained for complexes based on pyridyl carboxylate79 or phosphinate arms.…”

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confidence: 92%

Formation of Heteropolynuclear Lanthanide Complexes Using Macrocyclic Phosphonated Cyclam-Based Ligands

et al. 2020

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Ligands L1 and L2, respectively based on a cyclam and a cross-bridged cyclam scaffold functionalised at N1 and N8 by 6-phosphonic-2-methylene pyridyl groups are described. While 2 complexation of lanthanide (Ln) cations with L2 was not possible, a family of complexes has been prepared with L1, of the general formulae [LnL1D2]Cl (Ln 3+ = Lu, Tb, Yb) or [LnL1D] (Ln 3+ = Eu). The solution, structural, potentiometric and photophysical data for these novel ligands and their complexes have been investigated, including solid-state study by X-ray diffraction (L1, L2 and [EuL1H]), 1 H NMR complexation investigations (Lu 3+) as well as UV-Vis absorption and luminescence spectroscopy in water and D2O (pH ≈ 7). L1 forms 1:1 metal-ligand stoichiometric octadentate complexes in solution. Importantly the pyridyl phosphonate functions are capable of simultaneous chelation to the metal centre and of interaction with a second metal centre. 1 H NMR (Lu 3+) and spectrophotometric titrations of the isolated [TbL1]complex by EuCl3 salts demonstrated the formation of high order (hetero)polymetallic species in aqueous solution (H2O, pH = 7). Global analysis of the luminescence titration experiment points to the formation of 4:1, 3:1, and 3:2 [TbL1]:Eu heteropolynuclear assemblies, exhibiting a strong preference to forming [TbL1]3Eu2 at increased europium concentrations, with energy transfer occurring between the kinetically inert terbium complex and added europium cations.

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AMPED: a new platform for picolinate based luminescent lanthanide chelates

Cited by 18 publications

References 79 publications

Spectroscopic Properties of a Family of Mono‐ to Trinuclear Lanthanide Complexes

Spectroscopic Properties of a Family of Mono‐ to Trinuclear Lanthanide Complexes

Phosphonated Podand Type Ligand for the Complexation of Lanthanide CationsPhosphonated Podand Type Ligand for the Complexation of Lanthanide Cations

Formation of Heteropolynuclear Lanthanide Complexes Using Macrocyclic Phosphonated Cyclam-Based Ligands

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