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In the crystal of the title compound, C 6 H 6 F 8 O 4 , O—H...O hydrogen bonds involving the hydroxy groups connect the molecules, forming a two-dimensional network parallel to (100). These hydrogen-bonding interactions appear to drive the O—C—C—O torsion angles into a gauche – trans – trans series of conformations along the backbone of the molecule. 

Some bacterial heme proteins catalyze the coupling of two NO molecules to generate N₂O. We previously reported that a heme Fe–NO model engages in this N−N bond‐forming reaction with NO. We now demonstrate that (OEP)Co^II(NO) similarly reacts with 1 equiv of NO in the presence of the Lewis acids BX₃(X=F, C₆F₅) to generate N₂O. DFT calculations support retention of the Co^IIoxidation state for the experimentally observed adduct (OEP)Co^II(NO⋅BF₃), the presumed hyponitrite intermediate (P^.+)Co^II(ONNO⋅BF₃), and the porphyrin π‐radical cation by‐product of this reaction, and that the π‐radical cation formation likely occurs at the hyponitrite stage. In contrast, the Fe analogue undergoes a ferrous‐to‐ferric oxidation state conversion during this reaction. Our work shows that cobalt hemes are chemically competent to engage in the NO‐to‐N₂O conversion reaction.

 

All‐inorganic metal halides such as Cs₄PbX₆and CsPbX₃(X = Cl, Br, and I) are attracting global attention owing to their promise in optoelectronic applications. However, the presence of the toxic heavy metal lead (Pb) in these materials is a major concern. Here, a family of nontoxic high‐efficiency blue‐emitting all‐inorganic halides Rb₂CuX₃(X = Br and Cl) is reported; the compounds exhibit 1D crystal structures featuring anionic²⁻ribbons separated by Rb⁺cations. The measured record high photoluminescence quantum yield values range from 64% to 100% for Rb₂CuBr₃and Rb₂CuCl₃, respectively. Furthermore, the measured emission linewidths are quite narrow with full width at half maximum values of 54 and 52 nm for Rb₂CuBr₃and Rb₂CuCl₃, respectively. Single crystals of Rb₂CuCl₃demonstrate an anti‐Stokes photoluminescence signal, shown for the first time for Pb‐free metal halides. The discovery of highly efficient narrow blue emitters based on a nontoxic and inexpensive metal copper paves a way for the consideration of low‐cost and environmentally friendly copper halides for practical applications.