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1. X-ray absorption spectroscopy insights on the structure anisotropy and charge transfer in Chevrel Phase chalcogenides

   https://doi.org/10.1039/d1cp04851a  

   Hyler, Forrest P.; Wuille Bille, Brian A.; Ortíz-Rodríguez, Jessica C.; Sanz-Matias, Ana; Roychoudhury, Subhayan; Perryman, Joseph T.; Patridge, Christopher J.; Singstock, Nicholas R.; Musgrave, Charles B.; Prendergast, David; et al (July 2022, Physical Chemistry Chemical Physics)

   The electronic structure and local coordination of binary (Mo 6 T 8 ) and ternary Chevrel Phases (M x Mo 6 T 8 ) are investigated for a range of metal intercalant and chalcogen compositions. We evaluate differences in the Mo L 3 -edge and K-edge X-ray absorption near edge structure across the suite of chalcogenides M x Mo 6 T 8 (M = Cu, Ni, x = 1–2, T = S, Se, Te), quantifying the effect of compositional and structural modification on electronic structure. Furthermore, we highlight the expansion, contraction, and anisotropy of Mo 6 clusters within these Chevrel Phase frameworks through extended X-ray absorption fine structure analysis. Our results show that metal-to-cluster charge transfer upon intercalation is dominated by the chalcogen acceptors, evidenced by significant changes in their respective X-ray absorption spectra in comparison to relatively unaffected Mo cations. These results explain the effects of metal intercalation on the electronic and local structure of Chevrel Phases across various chalcogen compositions, and aid in rationalizing electron distribution within the structure. 

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2. Structural and electronic switching of a single crystal 2D metal-organic framework prepared by chemical vapor deposition

   https://doi.org/10.1038/s41467-020-19220-y  

   Claire, F. James; Solomos, Marina A.; Kim, Jungkil; Wang, Gaoqiang; Siegler, Maxime A.; Crommie, Michael F.; Kempa, Thomas J. (November 2020, Nature Communications)

   Abstract The incorporation of metal-organic frameworks into advanced devices remains a desirable goal, but progress is hindered by difficulties in preparing large crystalline metal-organic framework films with suitable electronic performance. We demonstrate the direct growth of large-area, high quality, and phase pure single metal-organic framework crystals through chemical vapor deposition of a dimolybdenum paddlewheel precursor, Mo₂(INA)₄. These exceptionally uniform, high quality crystals cover areas up to 8600 µm²and can be grown down to thicknesses of 30 nm. Moreover, scanning tunneling microscopy indicates that the Mo₂(INA)₄clusters assemble into a two-dimensional, single-layer framework. Devices are readily fabricated from single vapor-phase grown crystals and exhibit reversible 8-fold changes in conductivity upon illumination at modest powers. Moreover, we identify vapor-induced single crystal transitions that are reversible and responsible for 30-fold changes in conductivity of the metal-organic framework as monitored by in situ device measurements. Gas-phase methods, including chemical vapor deposition, show broader promise for the preparation of high-quality molecular frameworks, and may enable their integration into devices, including detectors and actuators. 

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3. Resolving the Solvation Structure and Transport Properties of Aqueous Zinc Electrolytes from Salt-in-Water to Water-in-Salt Using Neural Network Potential

   https://doi.org/10.1103/PRXEnergy.4.023004  

   Cao, Chuntian; Kingan, Arun; Hill, Ryan C; Kuang, Jason; Wang, Lei; Zhang, Chunyi; Carbone, Matthew R; van_Dam, Hubertus; Yoo, Shinjae; Yan, Shan; et al (April 2025, PRX Energy)

   ${\mathrm{Zn}\mathrm{Cl}}_2$solutions are promising electrolytes for aqueous zinc-ion batteries. Here, we report a joint computational and experimental study of the structural and dynamic properties of aqueous ${\mathrm{Zn}\mathrm{Cl}}_2$electrolytes with concentrations ranging from salt-in-water to water-in-salt (WIS). By developing a neural network potential (NNP) model, we perform molecular dynamics (MD) simulations with accuracy but at much larger lengths and longer timescales. The NNP predicted structures are validated by the structure factors measured by X-ray total scattering experiments. The MD trajectories provide a comprehensive and quantitative picture of the ${\mathrm{Zn}}^{2+}$solvation shell structures. Additionally, we find that the $\mathrm{O}-\mathrm{H}$covalent bonds in water are strengthened with increasing salt concentration, thus expanding the electrochemical stability window of aqueous electrolytes. In terms of dynamic properties, the calculated and experimentally measured conductivities are in good agreement. Through the analysis of the calculated cation transference number, we propose a three-stage charge carrier transport mechanism with increasing concentration: independent ion transport, strongly correlated ion transport, and small positive charge carrier diffusion through negatively charged polymeric clusters. Our study provides fundamental atomic scale insights into the structure and transport properties of the ${\mathrm{Zn}\mathrm{Cl}}_2$electrolyte that can aid the optimization and development of WIS electrolytes. 

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4. Mössbauer studies of the redox state of the ferric uptake regulator [2Fe–2S]2+ cluster in Escherichia coli

   https://doi.org/10.1016/j.jinorgbio.2025.112928  

   Fontenot, Chelsey R; Hoepner, Thomas; Xiong, Jin; Ding, Huangen; Popescu, Codrina V (September 2025, Journal of Inorganic Biochemistry)

   Ciurli, S (Ed.)

   The Ferric uptake regulator (Fur) proteins from Haemophilus influenzae and Escherichia coli overexpressed in E. coli cells (MC4100) grown in M9 medium supplemented with 57Fe were studied with Mössbauer spectroscopy. Previous studies have shown that Fur proteins from H. influenzae and E. coli bind a [2Fe-2S]2+ cluster in response to elevation of intracellular free iron content. Here we find that when the [2Fe-2S] 2+ clusters in purified Fur proteins are reduced with dithionite, the reduced clusters are quickly decomposed, forming compounds with two distinct spectral signatures of high spin Fe(II) in tetrahedral and octahedral coordination, respectively. The instability of the reduced [2Fe-2S]1+ cluster in Fur is unique, as the [2Fe-2S]2+ clusters in many other proteins can reversibly undergo one-electron reduction-oxidation. The Mössbauer spectra of whole E. coli cells overexpressing Fur proteins show a quadrupole doublet with the isomer shift of δ1 = 0.28 mm/s and ΔEQ1 = 0.52 mm/s, typical for oxidized [2Fe-2S]2+ clusters and identical with that in the purified Fur protein. The corresponding spectra in large applied magnetic fields show the diamagnetic pattern that unambiguously reveals an exchange-coupled system with a diamagnetic electronic ground state, which confirms its assignment to the oxidized [2Fe-2S]2+ cluster clusters from Fur. No reduced [2Fe-2S]1+ clusters of Fur are observed in the whole-cell E. coli spectra. The Mössbauer spectra of the whole-cell E. coli without the Fur expression do not contain the components associated with the [2Fe-2S]2+ cluster of Fur. 

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5. Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks

   https://doi.org/10.1039/D1SC01262B  

   Ghosh, Raja; Paesani, Francesco (June 2021, Chemical Science)

   null (Ed.)

   Understanding the underlying physical mechanisms that govern charge transport in two-dimensional (2D) covalent organic frameworks (COFs) will facilitate the development of novel COF-based devices for optoelectronic and thermoelectric applications. In this context, the low-energy mid-infrared absorption contains valuable information about the structure–property relationships and the extent of intra- and inter-framework “hole” polaron delocalization in doped and undoped polymeric materials. In this study, we provide a quantitative characterization of the intricate interplay between electronic defects, domain sizes, pore volumes, chemical dopants, and three dimensional anisotropic charge migration in 2D COFs. We compare our simulations with recent experiments on doped COF films and establish the correlations between polaron coherence, conductivity, and transport signatures. By obtaining the first quantitative agreement with the measured absorption spectra of iodine doped (aza)triangulene-based COF, we highlight the fundamental differences between the underlying microstructure, spectral signatures, and transport physics of polymers and COFs. Our findings provide conclusive evidence of why iodine doped COFs exhibit lower conductivity compared to doped polythiophenes. Finally, we propose new research directions to address existing limitations and improve charge transport in COFs for applications in functional molecular electronic devices. 

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