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1. The metallo-formate anions, M(CO ₂ ) ⁻ , M = Ni, Pd, Pt, formed by electron-induced CO ₂ activation

   https://doi.org/10.1039/c9cp01915d  

   Liu, Gaoxiang; Ciborowski, Sandra M.; Zhu, Zhaoguo; Chen, Yinlin; Zhang, Xinxing; Bowen, Kit H. (May 2019, Physical Chemistry Chemical Physics)

   The metallo-formate anions, M(CO 2 ) − , M = Ni, Pd, and Pt, were formed by electron-induced CO 2 activation. They were generated by laser vaporization and characterized by a combination of mass spectrometry, anion photoelectron spectroscopy, and theoretical calculations. While neutral transition metal atoms are normally unable to activate CO 2 , the addition of an excess electron to these systems led to the formation of chemisorbed anionic complexes. These are covalently bound, formate-like anions, in which their CO 2 moieties are significantly reduced. In addition, we also found evidence for an unexpectedly attractive interaction between neutral Pd atoms and CO 2 . 

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2. 10 ⁶ -fold faster C–H bond hydroxylation by a Co ^III,IV ₂ (µ-O) ₂ complex [via a Co ^III ₂ (µ-O)(µ-OH) intermediate] versus its Fe ^III Fe ^IV analog

   https://doi.org/10.1073/pnas.2307950120  

   Li, Yan; Abelson, Chase; Que, Lawrence; Wang, Dong (December 2023, Proceedings of the National Academy of Sciences)

   The hydroxylation of C–H bonds can be carried out by the high-valent Co^III,IV₂(µ-O)₂complex2asupported by the tetradentate tris(2-pyridylmethyl)amine ligand via a Co^III₂(µ-O)(µ-OH) intermediate (3a). Complex3acan be independently generated either by H-atom transfer (HAT) in the reaction of2awith phenols as the H-atom donor or protonation of its conjugate base, the Co^III₂(µ-O)₂complex1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm⁻¹associated with the symmetric Co–O–Co stretching mode of the Co₂O₂diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for1aand2aby Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their “diamond core” structural assignments. The independent generation of3aallows us to investigate HAT reactions of2awith phenols in detail, measure the redox potential and pK_aof the system, and calculate the O–H bond strength (D_O–H) of3ato shed light on the C–H bond activation reactivity of2a. Complex3ais found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal2ato be 10⁶-fold more reactive in oxidizing hydrocarbon C–H bonds than corresponding Fe^III,IV₂(µ-O)₂and Mn^III,IV₂(µ-O)₂analogs, an unexpected outcome that raises the prospects for using Co^III,IV₂(µ-O)₂species to oxidize alkane C–H bonds. 

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3. Application and Properties of Co ²⁺ -Doped BaAl ₂ Si ₂ O ₈ Blue Pigments in Glazes

   https://doi.org/10.1021/acsaom.3c00419  

   Wang, Zhiwei; Wang, Qiuying; Liu, Qin; Suthirakun, Suwit; Kaewraung, Wongsathorn; Jiang, Peng; Zhao, Hang; Xin, Xin; Subramanian, M A (February 2024, ACS Applied Optical Materials)
4. Infrared Photodissociation Spectra of [Sn(CO ₂ ) _n ] ⁻ Cluster Ions

   https://doi.org/10.1021/acs.jpca.8b00362  

   Thompson, Michael C.; Weber, J. Mathias (March 2018, The Journal of Physical Chemistry A)
5. White light emission from co-doped La ₂ Hf ₂ O ₇ nanoparticles with suppressed host → Eu ³⁺ energy transfer via a U ⁶⁺ co-dopant

   https://doi.org/10.1039/D1QI00134E  

   Gupta, Santosh K.; Modak, Brindaban; Modak, Pampa; Mao, Yuanbing (August 2021, Inorganic Chemistry Frontiers)

   null (Ed.)

   Controlled energy transfer has been found to be one of the most effective ways of designing tunable and white photoluminescent phosphors. Utilizing host emission to achieve the same would lead to a new dimension in the design strategy for novel luminescent materials in solid state lighting and display devices. In this work, we have achieved controlled energy transfer by suppressing the host to dopant energy transfer in La 2 Hf 2 O 7 :Eu 3+ nanoparticles (NPs) by co-doping with uranium ions. Uranium acts as a barrier between the oxygen vacancies of the La 2 Hf 2 O 7 host and Eu 3+ doping ions to increase their separation and reduce the non-radiative energy transfer between them. Density functional theory (DFT) calculations of defect formation energy showed that the Eu 3+ dopant occupies the La 3+ site and the uranium ion occupies the Hf 4+ site. Co-doping the La 2 Hf 2 O 7 :Eu 3+ NPs with uranium ions creates negatively charged lanthanum and hafnium vacancies making the system highly electron rich. Formation of cation vacancies is expected to compensate the excess charge in the U and Eu co-doped La 2 Hf 2 O 7 NPs suppressing the formation of oxygen vacancies. This work shows how one can utilize the full color gamut in the La 2 Hf 2 O 7 :Eu 3+ ,U 6+ NPs with blue, green and red emissions from the host, uranium and europium, respectively, to produce near perfect white light emission. 

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