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1. Understanding Soap Formation in Paint Films by 207Pb, 119Sn, and 13C Solid-State NMR

   Catalano, J. ; Yao, Y. ; Murphy, A. ; Zumbulyadis, N. ; Centeno, S.A. ; Dybowski, C. ( October 2014 , Materials science and technology)

   The formation of lead carboxylates (lead soaps) has been identified as the cause of deterioration of hundreds of oil paintings. Soaps form when heavy metal-containing pigments, for example lead white and lead-tin yellow, react with saturated fatty acids in the oil medium. Understanding the mechanism of the reactions requires chemical information, which can be obtained with solid-state ²⁰⁷Pb, ¹¹⁹Sn and ¹³C NMR spectroscopy. Using the chemical-shift tensors determined by solid-state NMR we can gain structural insights on the coordination environment of the lead carboxylates and identify and quantify components in a paint film mixture. We have examined the spectroscopy of lead-containing pigments, lead carboxylates, and model paint films that were subjected to accelerated aging. We have also begun to investigate the dynamics of soap formation by ¹³C NMR spectroscopy. The NMR methods applied to the model paint systems could also be applied to other lead-containing materials. 

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2. Enabling Visible Light Sensitization of Yb III , Nd III and Er III in Dimeric Ln III /Ga III Metallacrowns through Functionalization with Ru II Complexes for NIR‐II Multiplex Imaging

   https://doi.org/10.1002/ange.202416101  

   Bădescu‐Singureanu, Codruţa_C ; Nizovtsev, Anton_S ; Pecoraro, Vincent_L ; Petoud, Stéphane ; Eliseeva, Svetlana_V ( November 2024 , Angewandte Chemie)

   Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents suitable for this modality remains very scarce. In this work, we have synthesized and fully characterized, including theoretical calculations, a series of dimeric Ln^III/Ga^IIImetallacrowns bearing Ru^IIpolypyridyl complexes,LnRu‐3(Ln=Y^III, Yb^III, Nd^III, Er^III). Relaxed structures ofYRu‐3in the ground and the excited electronic states have been calculated using dispersion‐corrected density functional theory methods. Detailed photophysical studies ofLnRu‐3have demonstrated that characteristic emission signals of Yb^III, Nd^IIIand Er^IIIin the NIR‐II range can be sensitized upon excitation in the visible range through Ru^II‐centered metal‐to‐ligand charge transfer (MLCT) states. We have also showed that these NIR‐II signals are unambiguously detected in an imaging experiment using capillaries and biological tissue‐mimicking phantoms. This work opens unprecedented perspectives for NIR‐II multiplex imaging using Ln^III‐based molecular compounds.

    

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3. Enabling Visible Light Sensitization of Yb III , Nd III and Er III in Dimeric Ln III /Ga III Metallacrowns through Functionalization with Ru II Complexes for NIR‐II Multiplex Imaging

   https://doi.org/10.1002/anie.202416101  

   Bădescu‐Singureanu, Codruţa_C ; Nizovtsev, Anton_S ; Pecoraro, Vincent_L ; Petoud, Stéphane ; Eliseeva, Svetlana_V ( November 2024 , Angewandte Chemie International Edition)

   Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents suitable for this modality remains very scarce. In this work, we have synthesized and fully characterized, including theoretical calculations, a series of dimeric Ln^III/Ga^IIImetallacrowns bearing Ru^IIpolypyridyl complexes,LnRu‐3(Ln=Y^III, Yb^III, Nd^III, Er^III). Relaxed structures ofYRu‐3in the ground and the excited electronic states have been calculated using dispersion‐corrected density functional theory methods. Detailed photophysical studies ofLnRu‐3have demonstrated that characteristic emission signals of Yb^III, Nd^IIIand Er^IIIin the NIR‐II range can be sensitized upon excitation in the visible range through Ru^II‐centered metal‐to‐ligand charge transfer (MLCT) states. We have also showed that these NIR‐II signals are unambiguously detected in an imaging experiment using capillaries and biological tissue‐mimicking phantoms. This work opens unprecedented perspectives for NIR‐II multiplex imaging using Ln^III‐based molecular compounds.

    

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4. Fine-structure Transitions of Ne + , Ar + , Ne 2+ , and Ar 2+ Induced by Collisions with Atomic Hydrogen

   https://doi.org/10.3847/1538-4357/ad0e77  

   Yan, Pei-Gen ; Babb, James F ( January 2024 , The Astrophysical Journal)

   We calculate cross sections for fine-structure transitions of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with atomic hydrogen by using quantum-mechanical methods. Relaxation rate coefficients are calculated for temperatures up to 10,000 K. The temperature-dependent critical densities for the relaxation of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with H have been determined and compared to the critical densities for collisions with electrons. The present calculations will be useful for studies utilizing the infrared lines [Neii] 12.8, [Neiii] 15.6, [Neiii] 36.0, [Arii] 6.99, [Ariii] 8.99, and [Ariii] 21.8μm as diagnostics of, for example, planetary nebulae and star formation.

    

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5. Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53 Mn, 60 Fe, 182 Hf, and 244 Pu into Deep-sea Archives. Surfing the Wave?

   https://doi.org/10.3847/1538-4357/acafec  

   Wehmeyer, Benjamin ; López, Andrés Yagüe ; Côté, Benoit ; K. Pető, Maria ; Kobayashi, Chiaki ; Lugaro, Maria ( February 2023 , The Astrophysical Journal)

   While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a three-dimensional GCE model, we investigated the evolution of four SLRs:⁵³Mn,⁶⁰Fe,¹⁸²Hf, and²⁴⁴Pu with the aim of explaining detections of recent (within the last ≈1–20 Myr) deposition of live⁵³Mn,⁶⁰Fe, and²⁴⁴Pu of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneous arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar⁵³Mn,⁶⁰Fe, and²⁴⁴Pu are found within the same, or similar, layers of deep-sea sediments. We predict that¹⁸²Hf should also be found in such sediments at similar depths.

    

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