. (2014). Pristine organo-imido polyoxometalates as an anode for lithium ion batteries. RSC Advances: an international journal to further the chemical sciences, 4 (15), 7374-7379. Pristine organo-imido polyoxometalates as an anode for lithium ion batteries AbstractHere we have designed a strategy to improve the electronic conductivities of polyoxometalates (POMs) via property-oriented organic grafting for use in lithium-ion batteries (LIBs). POMs usually exhibit limited electronic conductivity that hinders their use in electronic applications. Organic grafting of POMs defines a valuable path for improving electronic conductivities of POMs, due to the enhanced metal to ligand charge transfer (MLCT) via d-π electronic interactions, and results in their feasible application in LIBs. Comparative practical and theoretical study of the effect of functional groups revealed that grafting of the remote electron withdrawing group (-SCN) on POMs via organo-imidoylization along with lower values of lowest unoccupied molecular orbitals (LUMO) results in an enhanced performance as Mo6-SCN shows initial discharge capacity of ∼1678 mA h g-1 with ∼85% capacity retention and coulombic efficiency ∼100% after 100 cycles. 2014 The Royal Society of Chemistry. Comparative practical and theoretical study of the effect of functional groups revealed that grafting of the remote electron withdrawing group (-SCN) on POMs via organo-imidoylization along with lower values of lowest unoccupied molecular orbitals (LUMO) results in an enhanced performance as Mo 6 -SCN shows initial discharge capacity of $1678 mA h g À1 with $85% capacity retention and coulombic efficiency $100% after 100 cycles.
A novel nanorod-like inorganic-organic hybrid compound based on polyoxometalate architectures and organic linkers was successfully synthesized, which exhibits reversible reduction-oxidation properties and fascinating photochromism under sunlight illumination.
Four novel organoimido derivatives of hexamolybdate containing a remote carboxyl group have been synthesized: [Bu4N]2[Mo6O18(N-C6H4-3-COOH)] (1), [Bu4N]2[Mo6O18(N-C6H4-2-CH3-4-COOH)] (2), [Bu4N]2[Mo6O18(N-C6H4-2-CH3-5-COOH)] (3), and [Bu4N]2[Mo6O18(N-C6H4-2-CH3-3-COOH)] (4) with 3-aminobenzoic acid, 4-amino-3-methylbenzoic acid, 3-amino-4-methylbenzoic acid, and 3-amino-2-methylbenzoic acid as the imido-releasing agents, respectively. Their structures have been characterized by IR, UV-vis, (1)H NMR, ESI-MS, and single-crystal X-ray diffraction techniques. Hydrogen bonding interactions play an important role in the supramolecular assemblies of these compounds in the solid state. Although the incorporated organic ligands are similar to each other, their supramolecular assembly behaviors are quite different. For compound 1, the dimer structure is formed via hydrogen bonding between the carboxyl group and the POM cluster of two neighboring cluster anions. For compound 2, the 1D chain structure is formed via hydrogen bonding between the carboxyl groups and the POM clusters of the cluster anions. For compound 3, the 2D plane structure is formed via two types of hydrogen bonding between the aromatic rings and the POM clusters of the cluster anions. For compound 4, the 1D plus 2D structures are formed via three types of hydrogen bonding between the aromatic rings and the POM clusters of the two types of cluster anions with different orientations.
Doubly modified: Polyoxometalates can incorporate a large number of different functionalities in a way that mixes the ligands in a one‐pot reaction. A class of mixed organoimido bifunctionalized hexamolybdates is presented that involves two different moieties L1 and L2, namely, differing aromatic, aromatic and aliphatic, and aliphatic moieties.
The functionalization of polyoxometalates (POMs), especially with an amino group to yield organonitrogenous derivatives of POMs, is an efficient approach to the enrichment of their structures and the diversification of their properties for various applications. The mechanism for the formation of organonitrogenous-derivatized hexamolybdates was explored by investigating the monofunctionalization of the [Mo(6)O(19)](2-) ion with methylamine using the density functional theory (DFT) method. The calculations show that the direct imidoylization of hexamolybdate with methylamine is both kinetically and thermodynamically unfavorable. However, this imidoylization was found to take place readily in the presence of dimethylcarbodiimide (DMC), for which the free-energy barrier was calculated to be +32.5 kcal mol(-1) in acetonitrile. Moreover, various factors controlling the efficiency of the imidoylization were examined. The calculations show that [W(5)MoO(19)](2-) has a relatively lower reactivity than [Mo(6)O(19)](2-), and that the imidoylization of [W(6)O(19)](2-) is an unfavorable process. With respect to the effect of carbodiimides, it is found that the catalytic activity is directly proportional to the electron-withdrawing effects of the substituents. As to the reactivity of R-NH(2) , the computation results indicate that the free-energy barriers of the substitution reactions are linearly correlated with the basicity constants (pK(b)) of the amino groups. It is noteworthy that the introduction of the proton dramatically decreases the free-energy barrier of the imidoylization of [Mo(6)O(19)](2-) catalyzed by DMC to 24.3 kcal mol(-1) in acetonitrile.
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