Synthesis and structural characterization of nitrite-coordinating CoII and CoIII complexes as models for the reaction center of Co-substituted nitrite reductase

Regeneration of NCM622 from end-of-life lithium-ion battery cathode materials

The boom of the electric vehicle industry significantly aggravates the demand for lithium-ion batteries (LIBs), especially the ternary cathode materials, however, the majority of end-of-life (EOL) LIBs on the market are batteries utilized in customer electronics. Here, we utilized the mixed EOL LIBs from cell phones and laptops to manufacture the LiNi_0.6Co0_.2Mn_0.2O₂ (NCM622) cathode material. A feasible, high efficiency (99.98% Co, 99.98% Ni, 99.99% Mn, and 99.99% Li), and ultra-fast leaching of EOL LIB cathodes was achieved. Thermodynamic calculations suggested that the coordination number, coordination species concentrations, and fractions have significant effects on the apparent activation energy and the equilibrium of the leaching reactions. The remanufactured NCM622 cathode material demonstrated a well-ordered layered hexagonal structure with a low Li⁺/Ni²⁺ mixing ratio, which facilitated reliable reversible capacity, low polarization, high rate capabilities (163.8 mA h g^-1), and capacity retention ratio (94.3%).

NO Generation from the Cross-Talks between Ene-diol Antioxidants and Nitrite at Metal Sites

The one-electron reduction of nitrite (NO₂^-) to nitric oxide (NO) and ene-diol oxidation are two important biochemical transformations. Employing mononuclear cobalt-nitrite complexes with Co^III and Co^II oxidation states, [(Bz₃Tren)Co^III(nitrite)₂](ClO₄) (1) and [(Bz₃Tren)Co^II(nitrite)](ClO₄) (2), this report illustrates NO release coupled to stepwise oxidation of ene-diol antioxidants such as l-ascorbic acid (AH₂) and catechol. Analysis of the AH₂ end-product reveals that the reaction with complex 1 affords dehydroascorbic acid. Intriguingly, a controlled oxidation of AH₂ with complex 2 results in a [Co^II]-bound ascorbyl radical-anion (8). Finally, NO release with the concomitant generation of metal-bound 3,5-di-tert-butyl-semiquinone radical anion from the reactions of 3,5-di-tert-butyl-catechol and [(Bz₃Tren)M^II(nitrite)](ClO₄) (2, M = Co; 4, M = Zn) provides mechanistic insights into the cross-talk between nitrite and ene-diols at the metal sites.

Synthesis and Structural Characterisation of Palladium(II) Complexes with N,N′,N-Tridentate N′-Substituted N,N-Di(2-picolyl)amines and their Application to Methyl Methacrylate Polymerisation

The reaction of [Pd(CH3CN)2Cl2] with N′-substituted N,N-di(2-picolyl)amine-based ancillary ligands, for example N,N-di(2-picolyl)cyclohexylmethylamine (L1), N,N-di(2-picolyl)benzylamine (L2), N,N-di(2-picolyl)aniline (L3), and 1,4-bis[bis(2-pyridylmethyl)aminomethyl]benzene (L4), in the presence of NaClO4 in ethanol yields a new series of [(NN′N)PdCl]X (X = ClO4, Cl) complexes, i.e. mononuclear [LnPdCl]ClO4 (Ln = L1, L2, L3) and binuclear [L4Pd2Cl2]Cl2. X-Ray crystallographic analysis determined that the Pd atom in complexes [(NN′N)PdCl]X showed a slightly distorted square-planar geometry involving three nitrogen atoms and a chlorido ligand. Moreover, the unit cell included a ClO4– or Cl– anion as the counterion. The complex [L1PdCl]ClO4 showed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane at 60°C among the mononuclear PdII complexes. Specifically, the activity of binuclear [L4Pd2Cl2]Cl2 was 2-fold higher than the corresponding mononuclear [L2PdCl]ClO4 per active palladium metal centre.