Synthesis and Characterization of a New Cu(II) Paddle-Wheel-like Complex with 4-Vinylbenzoate as an Inorganic Node for Metal-Organic Framework Material Design

A new Cu(II) paddle-wheel-like complex with 4-vinylbenzoate was synthesized using acetonitrile as the solvent. The complex was characterized by X-ray crystal diffraction, FT-IR, diffuse reflectance spectroscopy, thermogravimetric, differential scanning calorimetric, magnetic susceptibility, and electronic paramagnetic resonance analyses. The X-ray crystal diffraction analysis indicated that each copper ion was bound at an equatorial position to four oxygen atoms from the carboxylate groups of the 4-vinylbenzoate ligand in a square-based pyramidal geometry. The distance between the copper ions was 2.640(9) Å. The acetonitrile molecules were coordinated at the axial position to the copper ions. Exposure of the Cu(II) complex to humid air promoted the gradual replacement of the coordinated acetonitrile by water molecules, but the complex structure integrity remained. The EPR spectra exhibited signals attributed to the presence of a mixture of the monomeric (S = ½) and dimeric (S = 1) copper species in a possible 3:1 ratio. The magnetic studies revealed a peak at 50-100 K, which could be associated with the oxygen absorption capacity of the Cu(II)-vba complex.

Ion-Imprinted Polymer Structurally Preorganized Using a Phenanthroline-Divinylbenzoate Complex with the Cu(II) Ion as Template and Some Adsorption Results

The novel [Cuphen(VBA)₂H₂O] complex (phen: phenanthroline, VBA: vinylbenzoate) was prepared and used as a functional monomer to preorganize a new ion-imprinted polymer (IIP). By leaching the Cu(II) from the molecular imprinted polymer (MIP), [Cuphen(VBA)₂H₂O-co-EGDMA]_n (EGDMA: ethylene glycol dimethacrylate), the IIP was obtained. A non-ion-imprinted polymer (NIIP) was also prepared. The crystal structure of the complex and some physicochemical, spectrophotometric techniques were also used for the MIP, IIP, and NIIP characterization. The results showed that the materials are nonsoluble in water and polar solvents, which are the main features of polymers. The surface area of the IIP is higher than the NIIP demonstrated by the blue methylene method. The SEM images show monoliths and particles smoothly packed together on spherical and prismatic-spherical surfaces in the morphology of MIP and IIP, respectively. Moreover, the MIP and IIP could be considered as mesoporous and microporous materials, shown by the size of the pores determined by the BET and BJH methods. Furthermore, the adsorption performance of the IIP was studied using copper(II) as a contaminant heavy metal. The maximum adsorption capacity of IIP was 287.45 mg/g at 1600 mg/L Cu²⁺ ions with 0.1 g of IIP at room temperature. The Freundlich model was found to best describe the equilibrium isotherm of the adsorption process. The competitive results indicate that the stability of the Cu-IIP complex is higher than the Ni-IIP complex with a selectivity coefficient of 1.61.

In Situ Transformed Solid Electrolyte Interphase by Implanting a 4-Vinylbenzoic Acid Nanolayer on the Natural Graphite Surface

A solid electrolyte interphase (SEI) layer on a graphite anode plays a crucial role in deciding electrochemical properties of the electrode including the first Coulombic efficiency, rate capability, operating temperature, and long-term cycling stability. However, the ultrathin functional SEI layer is always naturally grown via electrolyte reduction decomposition reactions. Herein, we report a new strategy of in situ transformed solid electrolyte interphase of high stability by implanting a 4-vinylbenzoic acid (4-VBA) nanolayer on a mildly oxidized graphite surface. A 4-VBA layer of 40 nm contributes to the transformation of a robust and stable SEI layer, which not only significantly enhances the overall electrochemical performances of the natural graphite electrode but also greatly prolongs the cycle life of the full cell with the LiNi_0.6Co_0.2Mn_0.2O₂ cathode. The effectively suppressed surface evolution aroused from the stable organic SEI transformed from the implanted 4-VBA nanolayer explains the enhanced electrochemical properties.