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1. Investigation of Pb–B Bonding in PbB ₂ (BO) _n ⁻ ( n = 0–2): Transformation from Aromatic PbB ₂ ⁻ to Pb[B ₂ (BO) ₂ ] ^−/0 Complexes with BB Triple Bonds

   https://doi.org/10.1039/D3CP02800C  

   Chen, Qiang; Chen, Wei-Jia; Wu, Xin-Yao; Chen, Teng-Teng; Yuan, Rui-Nan; Lu, Hai-Gang; Yuan, Dao-Fu; Li, Si-Dian; Wang, Lai-Sheng (February 2024, Physical Chemistry Chemical Physics)

   Joint photoelectron spectroscopy and first-principles theory investigations indicate that the Pb-doped PbB₂(BO)_n⁻clusters (n= 0−2) undergo a transformation from σ + π doubly aromatic triangle PbB₂⁻to PbB₄(BO)₂^−/0complexes with a B≡B triple bond. 

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2. Organo‐Functionalized Lacunary Double Cubane‐Type Oxometallates: Synthesis, Structure, and Properties of [(M ^II Cl) ₂ (V ^IV O) ₂ {((HOCH ₂ CH ₂ )(H)N(CH ₂ CH ₂ O))(HN(CH ₂ CH ₂ O) ₂ )} ₂ ] (M=Co, Zn)

   https://doi.org/10.1002/chem.202301389  

   Shuaib, Damola T.; Swenson, LaSalle; Kaduk, James A.; Chang, Tieyan; Chen, Yu‐Sheng; McNeely, James; Khan, M. Ishaque (October 2023, Chemistry – A European Journal)

   Abstract Organofunctionalized tetranuclear clusters [(M^IICl)₂(V^IVO)₂{((HOCH₂CH₂)(H)N(CH₂CH₂O))(HN(CH₂CH₂O)₂)}₂] (1, M=Co,2: M=Zn) containing an unprecedented oxometallacyclic {M₂V₂Cl₂N₄O₈} (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo‐alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single‐crystal X‐ray diffraction structure analysis. The isostructural clusters are formed of edge‐sharing octahedral {VO₅N} and trigonal bipyramidal {MO₃NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of1and2in an unusual two‐mode fashion, unobserved previously. In the crystalline state, the clusters of1and2are joined by hydrogen bonds to form a three‐dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [J_iso(V^IV−V^IV)=−5.4(1); −3.9(2) cm⁻¹], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [J_iso(V^IV−Co^II)=−12.6 and −7.5 cm⁻¹] contained in1. 

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3. Solvent Effects in Hyperpolarization of ¹⁵ N Nuclei in [ ¹⁵ N ₃ ]Metronidazole and [ ¹⁵ N ₃ ]Nimorazole Antibiotics via SABRE‐SHEATH**

   https://doi.org/10.1002/anse.202400045  

   Yi, Anna P; Salnikov, Oleg G; Burueva, Dudari B; Chukanov, Nikita V; Chekmenev, Eduard Y; Koptyug, Igor V (August 2024, Analysis & Sensing)

   Abstract Metronidazole and nimorazole are antibiotics of a nitroimidazole group which also may be potentially utilized as hypoxia radiosensitizers for the treatment of cancerous tumors. Hyperpolarization of¹⁵N nuclei in these compounds using SABRE‐SHEATH (Signal Amplification By Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei) approach provides dramatic enhancement of detection sensitivity of these analytes using magnetic resonance spectroscopy and imaging. Methanol‐d₄is conventionally employed as a solvent in SABRE hyperpolarization process. Herein, we investigate SABRE‐SHEATH hyperpolarization of isotopically labeled [¹⁵N₃]metronidazole and [¹⁵N₃]nimorazole in nondeuterated methanol and ethanol solvents. Optimization of such hyperpolarization parameters as polarization transfer magnetic field, temperature, parahydrogen flow rate and pressure allowed us to obtain an average¹⁵N polarization of up to 7.2–7.4 % for both substrates. The highest¹⁵N polarizations were observed in methanol‐d₄for [¹⁵N₃]metronidazole and in ethanol for [¹⁵N₃]nimorazole. At a clinically relevant magnetic field of 1.4 T the¹⁵N nuclei of these substrates possess long characteristic hyperpolarization lifetimes (T₁) of ca. 1 to ca. 7 min. This study represents a major step toward SABRE in more biocompatible solvents, such as ethanol, and also paves the way for future utilization of these hyperpolarized nitroimidazoles as molecular contrast agents for MRI visualization of tumors. 

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4. WAIS Divide Ice Core δ ¹⁵ N(NO ₃ ⁻ ) Variability Over the Last Glacial‐Interglacial Cycle: Controlling Factors and Implications for Retrieving Surface Mass Balance Using Ice Core δ ¹⁵ N(NO ₃ ⁻ ) Records

   https://doi.org/10.1029/2025JD043712  

   Jiang, Zhuang; Alexander, Becky; McConnell, Joseph R; Schauer, Andrew; Geng, Lei (July 2025, Journal of Geophysical Research: Atmospheres)

   Abstract Ice core nitrate can serve as a valuable tracer for past atmospheric nitrogen oxide (NO_x) and oxidant concentrations. However, photolysis‐driven postdepositional processing can alter ice core nitrate signals and complicate their interpretation. We present a new nitrogen isotope (δ¹⁵N) record of nitrate measured in the West Antarctic Ice Sheet (WAIS) Divide ice core covering the last glacial period and Holocene. The glacialδ¹⁵N(NO₃⁻) is substantially higher than the Holoceneδ¹⁵N(NO₃⁻), with a glacial‐interglacial difference of (26.6 ± 5.7) ‰. All samples exhibit a strong negative correlation betweenδ¹⁵N(NO₃⁻) and the snow accumulation rate, suggesting that postdepositional processing is the primary driver of theδ¹⁵N(NO₃⁻) variability. Photochemical model calculations indicate that changes in the degree of postdepositional processing can fully explain the observed glacial‐interglacialδ¹⁵N(NO₃⁻) difference, with 12.7% and 31.8% of nitrate mass loss during the Holocene and glacial climate, respectively. Comparison with the Greenland GISP2δ¹⁵N(NO₃⁻) record indicates that the glacial level of postdepositional modification was higher at WAIS Divide despite its snow accumulation rate was twice that at Summit, Greenland. This is due to the higher light‐absorbing impurity contents in the GISP2 ice core that reduced postdepositional losses. We also assess the ability of usingδ¹⁵N(NO₃⁻) for past surface mass balance (SMB) reconstruction at WAIS Divide. We find this proxy is reliable for regions/periods with snow accumulation rates lower than 150 kg m⁻²a⁻¹. While exceeding this threshold, the assumption of a constantδ¹⁵N of initially deposited nitrate is no longer valid, leading to significant bias in SMB reconstruction such as WAIS Divide. 

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5. Enabling High‐Temperature Persistence Luminescence in Ca ₂ Si ₅ N ₈ :Eu ²⁺ , RE ³⁺ via Trap State Engineering

   https://doi.org/10.1002/adom.202502228  

   Akbar, Arslan; Zeler, Justyna; Owczarek, Aleksandra; Brgoch, Jakoah (November 2025, Advanced Optical Materials)

   Abstract Persistent luminescence at elevated temperatures can enable applications in high‐temperature thermal sensing, structural health monitoring, and anticounterfeiting. However, achieving long persistent luminescence lifetimes under such conditions requires careful control over trap state energies within the host crystal structure. Shallow traps (near the conduction band) release charge carriers too readily, quenching luminescence at high temperatures, whereas excessively deep traps may not depopulate at all. In this study, trap state engineering is investigated as a route to enable high‐temperature persistent luminescence in Ca₂Si₅N₈:Eu²⁺, a red‐orange‐emitting phosphor, by systematically exploring the addition of a second trivalent rare‐earth (RE= Dy³⁺, Tm³⁺, Nd³⁺, Tb³⁺). Co‐doping modifies the trap depth energy and distribution, enabling control over thermally activated charge release. Through detailed analysis of emission spectra, trap depths, and luminescence decay profiles from room temperature to 325 °C, it is demonstrated that the trap states can be tuned to maintain persistent luminescence at high temperatures, thereby enhancing high‐temperature performance. These findings establish a strategy for optimizing phosphor behavior in extreme thermal environments through targeted defect chemistry. 

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