Search

The title compound, which is potentially interesting as a building block for electrochemically active metallopolymers, was synthesized and characterized by single-crystal X-ray diffraction, IR and NMR spectroscopies. [ABSTRACT FROM AUTHOR]

As a cathode material for lithium-ion batteries, lithium iron phosphate (LiFePO4, LFP) successfully transitioned from laboratory bench to commercial product but was outshone by high capacity/high voltage lithium metal oxide chemistries. Recent changes in the global economy combined with advances in the battery pack design brought industry attention back to LFP. However, well-recognized intrinsic drawbacks of LiFePO4 such as relatively low specific capacity and poor electronic and ionic conductivity have not yet been fully mitigated. Integration of electrochemically active electron-conducting polymers (EAECPs) into the cathode structure to replace conventional auxiliary electrode components has been proposed as an effective strategy for further performance improvement of LFP batteries. In this review, we show how various combinations of polymer properties/functions have been utilized in composite LiFePO4 electrodes containing EAECP components. We present recent advances in the cathode design, materials, and methods and highlight the impact of synthetic strategies for the cathode preparation on its electrochemical performance in lithium-ion cells. We discuss advantages and limitations of the proposed approaches as well as challenges of their adoption by the battery manufactures. We conclude with perspectives on future development in this area. [ABSTRACT FROM AUTHOR]

Structures of recombinant phosphopantetheine adenylyltransferase (PPAT) from Mycobacterium tuberculosis (PPATMt) in the apo form and in complex with the substrate ATP were determined at 1.62 and 1.70 Å resolution, respectively, using crystals grown in microgravity by the counter-diffusion method. The ATP molecule of the PPATMt-ATP complex was located with full occupancy in the active-site cavity. Comparison of the solved structures with previously determined structures of PPATMt complexed with the reaction product dephosphocoenzyme A (dPCoA) and the feedback inhibitor coenzyme A (CoA) was performed using superposition on Cα atoms. The peculiarities of the arrangement of the ligands in the active-site cavity of PPATMt are described. The conformational states of the PPAT molecule in the consequent steps of the catalyzed reaction in the apo enzyme and the enzyme-substrate and enzyme-product complexes are characterized. It is shown that the binding of ATP and dPCoA induces the rearrangement of a short part of the polypeptide chain restricting the active-site cavity in the subunits of the hexameric enzyme molecule. The changes in the quaternary structure caused by this rearrangement are accompanied by a variation of the size of the inner water-filled channel which crosses the PPAT molecule along the threefold axis of the hexamer. The molecular mechanism of the observed changes is described. [ABSTRACT FROM AUTHOR]

Metal–ligand interactions in monomeric and polymeric transition metal complexes of Schiff base ligands largely define their functional properties and perspective applications. In this study, redox behavior of a nickel(II) N4-anilinosalen complex, [NiAmben] (where H2Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) was studied by cyclic voltammetry in solvents of different Lewis basicity. A poly-[NiAmben] film electrochemically synthesized from a 1,2-dichloroethane-based electrolyte was investigated by a combination of cyclic voltammetry, electrochemical quartz crystal microbalance, in situ UV-Vis spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag+. The polymer displayed multistep redox processes involving reversible transfer of the total of ca. 1.6 electrons per repeat unit, electrical conductivity over a wide potential range, and multiple color changes in correlation with electrochemical processes. Performance advantages of poly-[NiAmben] over its nickel(II) N2O2 Schiff base analogue were identified and related to the increased number of accessible redox states in the polymer due to the higher extent of electronic communication between metal ions and ligand segments in the nickel(II) N4-anilinosalen system. The obtained results suggest that electrosynthesized poly-[NiAmben] films may be viable candidates for energy storage and saving applications. [ABSTRACT FROM AUTHOR]