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1. Low-energy magnetic states of Tb adatom on graphene

   https://doi.org/10.1088/1361-648X/ad8fe9  

   Shaikh, Monirul; Klein, Alison; Wysocki, Aleksander L (November 2024, Journal of Physics: Condensed Matter)

   Abstract Electronic structure and magnetic interactions of a Tb adatom on graphene are investigated from first principles using combination of density functional theory and multiconfigurational quantum chemistry techniques including spin–orbit coupling (SOC) . We determine that the six-fold symmetry hollow site is the preferred adsorption site and investigate electronic spectrum for different adatom oxidation states including Tb³⁺, Tb²⁺, Tb¹⁺, and Tb⁰. For all charge states, the Tb $4f^8$configuration is retained with other adatom valence electrons being distributed over $5d_{xy}$, $5d_{x2+y2}$, and $6s/5d_0$single-electron orbitals. We find strong intra-site adatom exchange coupling that ensures that the $5d6s$spins are parallel to the4fspin. For Tb³⁺, the energy levels can be described by theJ = 6 multiplet split by the graphene crystal field (CF). For other oxidation states, the interaction of4felectrons with spin and orbital degrees of freedom of $6s5d$electrons in the presence of SOC results in the low-energy spectrum composed closely lying effective multiplets that are split by the graphene CF. Stable magnetic moment is predicted for Tb³⁺and Tb²⁺adatoms due to uniaxial magnetic anisotropy and effective anisotropy barrier around 440 cm⁻¹controlled by the temperature assisted quantum tunneling of magnetization through the third excited doublet. On the other hand, in-plane magnetic anisotropy is found for Tb¹⁺and Tb⁰adatoms. Our results indicate that the occupation of the $6s5d$orbitals can dramatically affect the magnetic anisotropy and magnetic moment stability of rare earth adatoms. 

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2. Dual Functions of CO ₂ Molecular Activation and 4 f Levels as Electron Transport Bridge in Dysprosium Single Atom Composite Photocatalysts with Enhanced Visible‐Light Photoactivities

   https://doi.org/10.1002/adfm.202104976  

   Zhao, Yue; Han, Zhendong; Gao, Guoyang; Zhang, Wanying; Qu, Yang; Zhu, Hongyang; Zhu, Peifen; Wang, Guofeng (July 2021, Advanced Functional Materials)

   Abstract The effect of rare earth (RE) single atoms on photocatalytic activity is very complex due to its special electronic configuration, which leads to few reports on the RE single atoms. Here, Dy³⁺single atom composite photocatalysts are successfully constructed based on both the special role of Dy³⁺and the special advantages of CdS/g‐C₃N₄heterojunction in the field of photocatalysis. The results show that an efficient way of electron transfer is provided to promote charge separation, and the dual functions of CO₂molecular activation of rare‐earth single atom and 4flevels as electron transport bridge are fully exploited. It is exciting that under visible‐light irradiation, the catalytic performance of CdS:Dy³⁺/g‐C₃N₄is≈6.9 times higher than that of pure g‐C₃N₄. The catalytic performance of CdS:Dy³⁺and CdS:Dy³⁺/g‐C₃N₄are≈7 and≈13.7 times higher than those of pure CdS, respectively. Besides, not all RE ions are suitable for charge transfer bridges, which is not only related to the 4flevels of RE ions but also related to the bandgap structure of CdS and g‐C₃N₄. The pattern of combining single‐atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity. 

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3. Introducing the Bis(mesitoyl)phosphide Ligand into Dinuclear Trivalent Rare Earth Metal Coordination Chemistry

   https://doi.org/10.1002/cplu.202400311  

   Deshapriya, Saroshan; Delano, IV, Francis; Demir, Selvan (August 2024, ChemPlusChem)

   Abstract Anionic ancillary ligands play a critical role in the construction of rare earth (RE) metal complexes due to the large influence on the stability of the molecule and engendering emergent electronic properties that are of interest in a plethora of applications. Supporting ligands comprising oxygen donor atoms are highly pursued in RE chemistry owing to the high oxophilicity innate to these ions. The scarcely employed bis(acyl)phosphide (BAP) ligands feature oxygen coordination sites and contain a phosphide backbone rendering it attractive for RE‐coordination chemistry. Here, we integrate bis(mesitoyl)phosphide (^mesBAP) as an ancillary ligand into RE^IIIchemistry to generate the first dinuclear trivalent RE complexes containing BAP ligands; [{^mesBAP}₂RE(THF)(μ‐Cl)]₂(RE=Y, (1), Gd (2), and Dy (3); THF=tetrahydrofuran). Each RE center is ligated to two monoanionic^mesBAP ligands, one THF molecule and one chloride ion. All three molecules were characterized through single‐crystal X‐ray diffraction,³¹P NMR, IR and UV‐Vis spectroscopy.³¹P,¹H and¹³C NMR on the diamagnetic yttrium congener1confirm asymmetric ligand coordination. DFT calculations conducted on2provided insight into the electronic structure. The magnetic properties of2and3were investigated via SQUID magnetometry. The Gd^IIIions exhibit weak antiferromagnetic coupling, corroborated by DFT results. 

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4. Solvent‐Dependent Spin‐Crossover Behavior in Semiconducting Co–Crystals of [Fe(1‐bpp) ₂ ] ²⁺ Cations and TCNQ ^δ− Anions (0<δ<1)

   https://doi.org/10.1002/ejic.202100707  

   Üngör, Ökten; Choi, Eun_Sang; Shatruk, Michael (November 2021, European Journal of Inorganic Chemistry)

   Abstract Co‐crystallization of the spin‐crossover (SCO) cationic complex, [Fe(1‐bpp)₂]²⁺(1‐bpp=2,6‐bis(pyrazol‐1‐yl)pyridine) with fractionally charged organic anion TCNQ^δ−(0<δ<1) afforded hybrid materials [Fe(1‐bpp)₂](TCNQ)_3.5 ⋅ 3.5MeCN (1) and [Fe(1‐bpp)₂](TCNQ)₄ ⋅ 4DCE (2), where TCNQ=7,7,8,8‐tetracyanoquinodimethane, MeCN=acetonitrile, and DCE=1,2‐dichloroethane. Both materials exhibit semiconducting behavior, with the room‐temperature conductivity values of 1.1×10⁻⁴ S/cm and 1.7×10⁻³ S/cm, respectively. The magnetic behavior of both complexes exhibits strong dependence on the content of the interstitial solvent. Complex1undergoes a gradual temperature‐driven SCO, with the midpoint temperature ofT_1/2=234 K. The partial solvent loss by1leads to the increase in theT_1/2value while complete desolvation renders the material high‐spin (HS) in the entire studied temperature range. In the case of2, the solvated complex shows a gradual SCO withT_1/2=166 K only when covered with a mother liquid, while the facile loss of interstitial solvent, even at room temperature, leads to the HS‐only behavior. 

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5. A Triply Negatively Charged Nanographene Bilayer with Spin Frustration

   https://doi.org/10.1002/anie.202217788  

   Wang, Wenqing; Ma, Xiao‐Hui; Liu, Min; Tang, Shuxuan; Ding, Xuguang; Zhao, Yue; Tan, Yuan‐Zhi; Kertesz, Miklos; Wang, Xinping (January 2023, Angewandte Chemie International Edition)

   Abstract We report on the largest open‐shell graphenic bilayer and also the first example of triply negatively charged radical π‐dimer. Upon three‐electron reduction, bilayer nanographene fragment molecule (C₉₆H₂₄Ar₆)₂(Ar=2,6‐dimethylphenyl) (1₂) was transformed to a triply negatively charged species1₂^3.−, which has been characterized by single‐crystal X‐ray diffraction, electron paramagnetic resonance (EPR) spectroscopy and magnetic properties on a superconducting quantum interference device (SQUID).1₂^3.−features a 96‐center‐3‐electron (96c/3e) pancake bond with a doublet ground state, which can be thermally excited to a quartet state. It consists of 34 π‐fused rings with 96 conjugatedsp²carbon atoms. Spin frustration is observed with the frustration parameterf>31.8 at low temperatures in1₂^3.−, which indicates graphene upon reduction doping may behave as a quantum spin liquid. 

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