Molecular Complexes of Emerging Tetravalent <scp>Rare‐Earth</scp> Metals

Li, Nan; Zhang, Wen‐Xiong

doi:10.1002/cjoc.202000258

Cited by 7 publications

(9 citation statements)

References 11 publications

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“…Until very recently, no other lanthanide than cerium was reported as a molecular complex in the formal +IV oxidation state [23, 25] . Also, formal Ce IV complexes are not restricted to organometallic complexes and other coordination compounds have been reported (Figure 8).…”

Section: Spectroscopic Singularitiesmentioning

confidence: 99%

“…If any unexpected properties appear in those unusual oxidation state species, it would then indicate that some aspects of the metal–ligand bonding nature might have been underestimated. In low‐valent species, the participation of the empty 5d‐manifold is in question, [18, 24] as is the role of strongly donating ligands in high‐valent species [23, 25] . This observation notably tends to indicate that the choice of the ligand should not be dictated only by the sterics but also by symmetry and energetic considerations, which is an important paradigm shift in lanthanide chemistry.…”

Section: Introductionmentioning

confidence: 99%

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Intermediate Valence States in Lanthanide Compounds

Tricoire

Mahieu

Simler

et al. 2021

Chemistry A European J

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Over more than 50 years, intermediate valence states in lanthanide compounds have often resulted in unexpected or puzzling spectroscopic and magnetic properties. Such experimental singularities could not be rationalised until new theoretical models involving multiconfigurational electronic ground states were established. In this minireview, the different singularities that have been observed among lanthanide complexes are highlighted, the models used to rationalise them are detailed and how such electronic effects may be adjusted depending on energy and symmetry considerations is considered. Understanding and tuning the ground‐state multiconfigurational behaviour in lanthanide complexes may open new doors to modular and unusual reactivities.

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Section: Spectroscopic Singularitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intermediate Valence States in Lanthanide Compounds

Tricoire

Mahieu

Simler

et al. 2021

Chemistry A European J

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“…There are seventeen elements in the periodic tables [including Sc (21), Y (39), and La (57)-Lu (71)] that are considered as rareearth elements and commonly exhibit +3 (III) oxidation states (Gai et al, 2014;Sharma et al, 2017a). In addition, other elements may also exhibit +4 and +2 oxidation states such as Sm 2+ , Ce 4+ , Eu 2+ , Tb 4+ , and Yb 2+ ions (Su et al, 2002;Anghel et al, 2017;Runowski et al, 2020a;Li and Zhang, 2020). The electronic configuration of the lanthanide (Ln 3+ ) series, particularly in the +3 state, is represented as [Xe] 4f n .…”

Section: Fundamentals Of Lanthanide Ions and Origin Of Their Spectroscopic Featuresmentioning

confidence: 99%

Lanthanide-Doped Luminescent Nanophosphors via Ionic Liquids

Sharma¹,

Ghosh

2021

Front. Chem.

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Lanthanide (Ln3+) ion(s)-doped or rare-earth ion(s)-doped nanomaterials have been considered a very important class of nanophosphors for various photonic and biophotonic applications. Unlike semiconductors and organic-based luminescent particles, the optical properties of Ln3+-doped nanophosphors are independent of the size of the nanoparticles. However, by varying the crystal phase, morphology, and lattice strain of the host materials along with making core-shell structure, the relaxation dynamics of dopant Ln3+ ions can be effectively tuned. Interestingly, a judicious choice of dopant ions leads to unparallel photophysical dynamics, such as quantum cutting, upconversion, and energy transfer. Recently, ionic liquids (ILs) have drawn tremendous attention in the field of nanomaterials synthesis due to their unique properties like negligible vapor pressure, nonflammability, and, most importantly, tunability; thus, they are often called “green” and “designer” solvents. This review article provides a critical overview of the latest developments in the ILs-assisted synthesis of rare-earth-doped nanomaterials and their subsequent photonic/biophotonic applications, such as energy-efficient lighting and solar cell applications, photodynamic therapy, and in vivo and in vitro bioimaging. This article will emphasize how luminescence dynamics of dopant rare-earth ions can be tuned by changing the basic properties of the host materials like crystal phase, morphology, and lattice strain, which can be eventually tuned by various properties of ILs such as cation/anion combination, alkyl chain length, and viscosity. Last but not least, different aspects of ILs like their ability to act as templating agents, solvents, and reaction partners and sometimes their “three-in-one” use in nanomaterials synthesis are highlighted along with various photoluminescence mechanisms of Ln3+ ion like up- and downconversion (UC and DC).

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“…It is the efforts led independently by Mazzanti 32−35 and La Pierre 36−38 that have broken new ground in the chemistry of tetravalent lanthanide complexes. 39 A number of representative Tb(IV) complexes are collected in time order as shown in Scheme 1, the first being . 33,34 Out of the small number of tetravalent lanthanide complexes, these of Pr(IV) and Tb(IV), featuring, respectively, 4f 1 and 4f 7 electron configurations, are magnetically attractive, both capable of providing a pure nuclear-spin environment and hyperfine coupling between nuclear and electronic spins.…”

Section: ■ Introductionmentioning

confidence: 99%

Tetravalent Terbium Chelates: Stability Enhancement and Property Tuning

Xue,

Ding,

Jiang

et al. 2023

Precision Chemistry

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Coordination chemistry of rare-earth elements has been dominated by the +3 oxidation state. Complexes with highervalence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials. Herein, four tetravalent terbium complexes (2−5) of the common formula [Tb(OSiPh 3 ) 4 L] (L = ethylene glycol dimethyl ether (DME), 2,2 ' -bipyridine (bpy), 2,2 'bipyrimidine (bpym), and 1,10-phenanthroline (phen)) are reported. Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV) ion situated in a distorted octahedral coordination environment formed by four triphenylsiloxido ligands and a bidentate chelating ligand. The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor. More significantly, the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes, as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III) process and by the changes in their absorption spectra. The experimental findings are augmented with quantum theoretical calculations in which the ligand π-donation to the 5d orbitals of the Tb(IV) center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed. Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes, ranging from 0.1071(22) to 1.1484(112) cm −1 and comparable to the values reported for analogous Tb(IV) complexes.

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Molecular Complexes of Emerging Tetravalent Rare‐Earth Metals

Cited by 7 publications

References 11 publications

Intermediate Valence States in Lanthanide Compounds

Intermediate Valence States in Lanthanide Compounds

Lanthanide-Doped Luminescent Nanophosphors via Ionic Liquids

Tetravalent Terbium Chelates: Stability Enhancement and Property Tuning

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