Diastereoselective formation of luminescent dinuclear lanthanide(iii) helicates with enantiomerically pure tartaric acid derived bis(β-diketonate) ligands

Albrecht, Markus; Schmid, Sören; Dehn, Sabrina; Wickleder, Claudia; Zhang, Shuang; Bassett, Andrew P.; Pikramenou, Zoe; Fröhlich, Roland

doi:10.1039/b705090a

Cited by 50 publications

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“…For Eu III ions the luminescence spectra consist of sharp peaks at given positions due to 4f 6 →4f 6 transitions, for example, 5 D 0 → 7 F J ( J =0–6) in the emission spectrum. In most cases the peak with the highest intensity is that of J =2, located in the red at about 620 nm 45. The absence of these signals clearly shows the absence of any Eu 3+ impurity.…”

Section: Resultsmentioning

confidence: 96%

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Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)

Harder

Naglav

Ruspic

et al. 2013

Chemistry A European J

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The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)⋅⋅⋅Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215 K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature strong orange photoluminescence (quantum yield: 45 %): excitation at 412 nm (24,270 cm(-1)) gives a symmetrical single band in the emission spectrum at 606 nm (νmax =16495 cm(-1), FWHM: 2090 cm(-1), Stokes-shift: 2140 cm(-1)), which is assigned to a 4f(6)5d(1) → 4f(7) transition of Eu(II). These remarkable values compare well to those for Eu(II)-doped ionic host lattices and are likely caused by the rigidity of the [Eu(Cp(BIG))2] complex. Sharp emission signals, typical for Eu(III), are not visible.

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Section: Resultsmentioning

confidence: 96%

“…In most cases the peak with the highest intensity is that of J = 2, located in the red at about 620 nm. [45] The absence of these signals clearly shows the absence of any Eu 3 + impurity.…”

Section: Photoluminescence Of [Eu(cp Big ) 2 ]mentioning

confidence: 99%

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)

Harder

Naglav

Ruspic

et al. 2013

Chemistry A European J

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“…Control of this stereoselectivity 6-9 is a key issue in these self-assemblies, in particular to develop chiral functional materials such as chiroptical probes, 10 molecular switches 11,12 and sensors. 10, [15][16][17] We are interested in discovering a new type of chiral supramolecule as a potential chiroptical probe for biological and sensing applications. Research in this area has led to a number of unique structures of chiral lanthanide assemblies appearing in various studies over the past decade.…”

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Lanthanide supramolecular helical diastereoselective breaking induced by point chirality: mixture or P-helix, M-helix

et al. 2015

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The self-assembly of lanthanide (europium or lanthanium) bimetallic triple helicates from two closely related chiral ligands resulted in a very different supramolecular phenomenon. One gave rise to significantly diastereoselective formation of a triple helicate, whereas the other led to diastereoselective breaking to generate a mixture of P and M diastereomers in ∼1 : 1.1 ratio. The first X-ray crystal structure of a chiral ligand based lanthanide triple-helicate indicates that successive CH-π interactions were found to maintain the supramolecular helical structure.

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“…The sensitising ability of the ligands improves in the series 3a < 3b << 3d . The corresponding terbium(III) ( 3d ) 3 Tb 2 and holmium(III) complexes ( 3d ) 3 Ho 2 also show characteristic spectra for the respective lanthanide(III) metal ions 13.…”

Section: Homodinuclear Lanthanide Helicatesmentioning

confidence: 99%

Homodinuclear f–f and Heterodinuclear f–p Lanthanide Helicates

Albrecht

2010

Zeitschrift anorg allge chemie

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Lanthanide helicates are of interest due to their ability to emit either in the visible or in the NIR region. In this context it is important to prepare heterodinuclear helicates and to use them for the investigation of intramolecular communication processes between different complex units. In here we describe the ligand synthesis and selfassembly of homo-and heterodinuclear helicates based on β-diketonate, catechol-acyl hydrazone and 2-amido-8-hydroxyquinoline li-

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Diastereoselective formation of luminescent dinuclear lanthanide(iii) helicates with enantiomerically pure tartaric acid derived bis(β-diketonate) ligands

Abstract: The chiral tartaric acid derived bis(b-diketonate) ligands 1-3-H 2 diastereoselectively form dinuclear triple-stranded helicates with a series of lanthanide(III) ions

Cited by 50 publications

References 57 publications

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)

Lanthanide supramolecular helical diastereoselective breaking induced by point chirality: mixture or P-helix, M-helix

Homodinuclear f–f and Heterodinuclear f–p Lanthanide Helicates

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Diastereoselective formation of luminescent dinuclear lanthanide(iii) helicates with enantiomerically pure tartaric acid derived bis(β-diketonate) ligands

Abstract: The chiral tartaric acid derived bis(b-diketonate) ligands 1-3-H 2 diastereoselectively form dinuclear triple-stranded helicates with a series of lanthanide(III) ions

Cited by 50 publications

References 57 publications

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [EuII(CpBIG)2] (CpBIG=(4‐nBu‐C6H4)5‐Cyclopentadienyl)

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [EuII(CpBIG)2] (CpBIG=(4‐nBu‐C6H4)5‐Cyclopentadienyl)

Lanthanide supramolecular helical diastereoselective breaking induced by point chirality: mixture or P-helix, M-helix

Homodinuclear f–f and Heterodinuclear f–p Lanthanide Helicates

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Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)

Physical Properties of Superbulky Lanthanide Metallocenes: Synthesis and Extraordinary Luminescence of [Eu^II(Cp^BIG)₂] (Cp^BIG=(4‐nBu‐C₆H₄)₅‐Cyclopentadienyl)