Spectroscopy of Lanthanide Complexes

Sastri, V. S.; Bünzli, Jean‐Claude G.; Rao, V. Ramachandra; Rayudu, G.V.S.; Perumareddi, Jayarama R.

doi:10.1016/b978-044451010-5/50022-5

Cited by 10 publications

(7 citation statements)

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“…These quantum yields are lower than those of the comparable (tpen)Ln(OTf) 3 complexes, likely due to the increased number of C–H bonds present from the cyclohexane backbone and the resulting loss of sensitization energy through C–H vibrations . Utilizing the analogous gadolinium complex, the triplet energy of the tpdac ligand was determined to be around 24150 cm –1 (Figure S18), which is consistent with the energy levels of the emissive lanthanide states (17700 cm –1 , 17300 cm –1 , 20500 cm –1 , and 21000 cm –1 , respectively) and the respective quantum yields observed. As expected for lanthanide-based emitters, long luminescence lifetimes were observed for the strong emitters (0.95 and 3.3 ms for Eu and Tb, respectively), while shorter lifetimes were obtained for the weakly luminescent complexes (25 and 20 μs for Sm and Dy, respectively).…”

Section: Resultsmentioning

confidence: 61%

Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

2020

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We report the synthesis and characterization of C 2 -symmetrical lanthanide complexes supported by enantiopure hexadentate ligands derived from 1,2-diaminocyclohexane. Coordination of (R,R)-or (S,S)-N,N,N′,N′-tetrakis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane (tpdac) to samarium, europium, terbium, and dysprosium generates the corresponding C 2 -symmetrical (tpdac)Ln(OTf) 3 complexes in high yields. The tpdac ligands are competent sensitizers for lanthanide luminescence, yielding modest emissions (Φ of ≤28%). Additionally, the complexes exhibit strong circularly polarized luminescence (|g lum | values of up to 0.13, 0.09, 0.22, and 0.15 for Sm, Eu, Tb, and Dy, respectively) in solution. We also observed that some transitions typically associated with small dissymmetry factors exhibit unusually high |g lum | values and, therefore, should not be overlooked in future studies.

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Section: Resultsmentioning

confidence: 61%

Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

2020

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“…UV-Vis data for ligand and complexes are presented in Table S1. In the NIR region of spectrum, the characteristic f-f transitions form the ground state 6 H 5/2 to 6 F multiplet of Sm 3+ ion (4f 5 ) are observed (Figure 2) [40].…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Structural Investigation of New Bio-Relevant Complexes of Lanthanides with 5-Hydroxyflavone: DNA Binding and Protein Interaction Studies

et al. 2016

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Abstract:In the present work, we attempted to develop new metal coordination complexes of the natural flavonoid 5-hydroxyflavone with Sm(III), Eu(III), Gd(III), Tb(III). The resultant hydroxo complexes have been characterized by a variety of spectroscopic techniques, including fluorescence, FT-IR, UV-Vis, EPR and mass spectral studies. The general chemical formula of the complexes is [Ln(C 15 H 9 O 3 ) 3 (OH) 2 (H 2 O) x ]·nH 2 O, where Ln is the lanthanide cation and x = 0 for Sm(III), x = 1 for Eu(III), Gd(III), Tb(III) and n = 0 for Sm(III), Gd(III), Tb(III), n = 1 for Eu(III), respectively. The proposed structures of the complexes were optimized by DFT calculations. Theoretical calculations and experimental determinations sustain the proposed structures of the hydroxo complexes, with two molecules of 5-hydroxyflavone acting as monoanionic bidentate chelate ligands. The interaction of the complexes with calf thymus DNA has been explored by fluorescence titration and UV-Vis absorption binding studies, and revealed that the synthesized complexes interact with DNA with binding constants (K b )~10 4 . Human serum albumin (HSA) and transferrin (Tf) binding studies have also been performed by fluorescence titration techniques (fluorescence quenching studies, synchronous fluorescence spectra). The apparent association constants (K a ) and thermodynamic parameters have been calculated from the fluorescence quenching experiment at 299 K, 308 K, and 318 K. The quenching curves indicate that the complexes bind to HSA with smaller affinity than the ligand, but to Tf with higher binding affinities than the ligand.

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“…In complex [Yb 2 Tb], the neighboring DTPA-bound Tb III is more readily accessible due to a larger ionic radius and reduction in kinetic stability of the DTPA binding pocket, resulting in ∼1 bound water molecule ( Idée et al, 2009 ; Sørensen and Faulkner, 2018 ). Similarly, in the complex [Eu 2 Tb], q = 1.0 for the DO3A Eu III center as a result of the slightly larger 9 coordinate ionic radius ( Sastri et al, 2003 ) which competes with the steric bulk of the DO3A macrocycle to allow inclusion of 1 solvent donor. In the case of the Tb III (DTPA) centre in [Eu 2 Tb], an apparent q value of 2.4 is determined.…”

Section: Resultsmentioning

confidence: 99%

Heterometallic lanthanide complexes with site-specific binding that enable simultaneous visible and NIR-emission

Thornton,

Hemsworth,

Hay

et al. 2023

Front. Chem.

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Macrocyclic lanthanide complexes have become widely developed due to their distinctive luminescence characteristics and wide range of applications in biological imaging. However, systems with sufficient brightness and metal selectivity can be difficult to produce on a molecular scale. Presented herein is the stepwise introduction of differing lanthanide ions in a bis-DO3A/DTPA scaffold to afford three trinuclear bimetallic [Ln2Ln’] lanthanide complexes with site-specific, controlled binding [(Yb2Tb), (Eu2Tb), (Yb2Eu)]. The complexes display simultaneous emission from all LnIII centers across the visible (TbIII, EuIII) and near infra-red (YbIII) spectrum when excited via phenyl ligand sensitization at a wide range of temperatures and are consequently of interest for exploiting imaging in the near infra-red II biological window. Analysis of lifetime data over a range of excitation regimes reveals intermetallic communication between TbIII and EuIII centers and further develops the understanding of multimetallic lanthanide complexes.

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Spectroscopy of Lanthanide Complexes

Cited by 10 publications

References 3 publications

Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Synthesis and Structural Investigation of New Bio-Relevant Complexes of Lanthanides with 5-Hydroxyflavone: DNA Binding and Protein Interaction Studies

Heterometallic lanthanide complexes with site-specific binding that enable simultaneous visible and NIR-emission

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Spectroscopy of Lanthanide Complexes

Cited by 10 publications

References 3 publications

Circularly Polarized Luminescence from Enantiopure C2-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Circularly Polarized Luminescence from Enantiopure C2-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Synthesis and Structural Investigation of New Bio-Relevant Complexes of Lanthanides with 5-Hydroxyflavone: DNA Binding and Protein Interaction Studies

Heterometallic lanthanide complexes with site-specific binding that enable simultaneous visible and NIR-emission

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Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Circularly Polarized Luminescence from Enantiopure C₂-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes