ACS Organic & Inorganic Au最新文献

Recently, we reported on the synthesis and performance of a cross-linked single-anion-conducting solid-state electrolyte (SSE) based on quaternized poly(dimethylaminomethylstyrene) (pDMAMS⁺) via initiated chemical vapor deposition (iCVD). In the homopolymer pDMAMS⁺-based SSE, the cross-linking occurs at the positively charged ammonium cation sites, hindering ion transport and conductivity. To improve ionic conductivity, we now report on a copolymer system, comprising DMAMS and divinylbenzene (DVB). Incorporating DVB moves the cross-links to the polymer backbone leaving the quaternary ammonium cation and its paired anion with maximal dynamic freedom. We evaluate the structure-transport relationships of a series of p[DVB-DMAMS] copolymers with varying DVB content using electrochemical impedance spectroscopy, nuclear magnetic resonance spectroscopy, and small- and wide-angle X-ray scattering. Our best composition containing 2.5 wt % DVB provides 1 mS cm^-1 single-ion OH^- conductivity under hydrated conditions, a significant improvement over the 0.01 mS cm^-1 of the hydrated homopolymer pDMAMS⁺ SSE. All copolymer compositions support Zn-ZnO and Ag-Zn electrochemical reduction-oxidation (redox) chemistry, which demonstrates the feasibility of a Ag-Zn battery using an alkaline single-ion-conducting SSE. Galvanostatic cycling shows some transport of Ag through the polymer electrolyte, however the deleterious effects of Ag migration can be partially mitigated by transitioning from a two-dimensional (2D) planar electrode to a 3D sponge electrode. With these promising results, the foundation is laid for using single-anion-conducting SSEs within alkaline Zn batteries.

Recently, we reported on the synthesis and performance of a cross-linked single-anion-conducting solid-state electrolyte (SSE) based on quaternized poly(dimethylaminomethylstyrene) (pDMAMS⁺) via initiated chemical vapor deposition (iCVD). In the homopolymer pDMAMS⁺-based SSE, the cross-linking occurs at the positively charged ammonium cation sites, hindering ion transport and conductivity. To improve ionic conductivity, we now report on a copolymer system, comprising DMAMS and divinylbenzene (DVB). Incorporating DVB moves the cross-links to the polymer backbone leaving the quaternary ammonium cation and its paired anion with maximal dynamic freedom. We evaluate the structure–transport relationships of a series of p[DVB-DMAMS] copolymers with varying DVB content using electrochemical impedance spectroscopy, nuclear magnetic resonance spectroscopy, and small- and wide-angle X-ray scattering. Our best composition containing 2.5 wt % DVB provides 1 mS cm^–1 single-ion OH^– conductivity under hydrated conditions, a significant improvement over the 0.01 mS cm^–1 of the hydrated homopolymer pDMAMS⁺ SSE. All copolymer compositions support Zn–ZnO and Ag–Zn electrochemical reduction–oxidation (redox) chemistry, which demonstrates the feasibility of a Ag–Zn battery using an alkaline single-ion-conducting SSE. Galvanostatic cycling shows some transport of Ag through the polymer electrolyte, however the deleterious effects of Ag migration can be partially mitigated by transitioning from a two-dimensional (2D) planar electrode to a 3D sponge electrode. With these promising results, the foundation is laid for using single-anion-conducting SSEs within alkaline Zn batteries.

Sulfinamides constitute adaptable S(IV) intermediates with a sulfur stereocenter, having emerging interest in divergent synthesis of high-valent S(VI) functional bioisosteres. Recent years have witnessed the strategic development of mild and selective synthetic routes for highly functionalized sulfinamides, employing stable organometallic reagents, carbon-centered radical precursors, and other abundant coupling partners merged with various sulfur reagents in the arena of metal, photoredox, and organocatalysis. Furthermore, asymmetric metal and organocatalysis have enabled the stereoselective synthesis of enantioenriched sulfinamides. In this Perspective, we present the recent (2021 to present) advancement of various synthetic methods toward sulfinamides.

Sulfinamides constitute adaptable S(IV) intermediates with a sulfur stereocenter, having emerging interest in divergent synthesis of high-valent S(VI) functional bioisosteres. Recent years have witnessed the strategic development of mild and selective synthetic routes for highly functionalized sulfinamides, employing stable organometallic reagents, carbon-centered radical precursors, and other abundant coupling partners merged with various sulfur reagents in the arena of metal, photoredox, and organocatalysis. Furthermore, asymmetric metal and organocatalysis have enabled the stereoselective synthesis of enantioenriched sulfinamides. In this Perspective, we present the recent (2021 to present) advancement of various synthetic methods toward sulfinamides.

Solvent effects play a critical role in ionic chemical reactions and have been a research topic for a long time. The solvent molecules in the first solvation shell of the solute are the most important solvating species. Consequently, manipulation of the structure of this shell can be used to control the reactivity and selectivity of ionic reactions. In this work, we report extensive experimental and insightful computational studies of the effects of adding diverse fluorinated bulky alcohols with different solvation abilities to the fluorination reaction of alkyl bromides with potassium fluoride promoted by 18-crown-6. We found that adding a stoichiometric amount of these alcohols to the acetonitrile solution has an important effect on the kinetics and selectivity. The most effective alcohol was 2-trifluoromethyl-2-propanol (TBOH-F3), and the use of 3 equiv of this alcohol to fluorinate a primary alkyl bromide led to a 78% fluorination yield in just 6 h of reaction time at a mild temperature of 82 °C, with 8% of E2 yield. The more challenging secondary alkyl bromide substrate obtained 44% fluorination yield and 56% E2 yield at 18 h of reaction time. More fluorinated alcohols with six or more fluorine atoms have resulted in relatively acidic alcohols, leading to large amounts of the corresponding ethers of these alcohols as side products. The widely used hexafluoroisopropanol (HFIP) was the least effective one for monofluorination, indicating that both acidity and bulkiness are important features of the alcohols for promoting fluorination using KF salt. Nevertheless, the ether of HFIP can be easily formed with the substrate, generating a highly fluorinated ether product. Theoretical calculations predict ΔG^‡ in close agreement with the experiments and explain the higher selectivity induced by the fluorinated bulky alcohols in relation to the use of crown ether alone.

Solvent effects play a critical role in ionic chemical reactions and have been a research topic for a long time. The solvent molecules in the first solvation shell of the solute are the most important solvating species. Consequently, manipulation of the structure of this shell can be used to control the reactivity and selectivity of ionic reactions. In this work, we report extensive experimental and insightful computational studies of the effects of adding diverse fluorinated bulky alcohols with different solvation abilities to the fluorination reaction of alkyl bromides with potassium fluoride promoted by 18-crown-6. We found that adding a stoichiometric amount of these alcohols to the acetonitrile solution has an important effect on the kinetics and selectivity. The most effective alcohol was 2-trifluoromethyl-2-propanol (TBOH-F3), and the use of 3 equiv of this alcohol to fluorinate a primary alkyl bromide led to a 78% fluorination yield in just 6 h of reaction time at a mild temperature of 82 °C, with 8% of E2 yield. The more challenging secondary alkyl bromide substrate obtained 44% fluorination yield and 56% E2 yield at 18 h of reaction time. More fluorinated alcohols with six or more fluorine atoms have resulted in relatively acidic alcohols, leading to large amounts of the corresponding ethers of these alcohols as side products. The widely used hexafluoroisopropanol (HFIP) was the least effective one for monofluorination, indicating that both acidity and bulkiness are important features of the alcohols for promoting fluorination using KF salt. Nevertheless, the ether of HFIP can be easily formed with the substrate, generating a highly fluorinated ether product. Theoretical calculations predict ΔG ^‡ in close agreement with the experiments and explain the higher selectivity induced by the fluorinated bulky alcohols in relation to the use of crown ether alone.

Amide hydrogenation is an important process for producing amines, with the development of efficient heterogeneous catalysts relying on the creation of bimetallic active sites where the two components interact synergistically. In this study, we develop a method for preparing catalysts using ligand-functionalized organometallic polyoxometalates by synthesizing a Rh–Mo organometallic polyoxometalate, [(RhCp^E)₄Mo₄O₁₆] (Cp^E = C₅(CH₃)₃(COOC₂H₅)₂), with Rh–O–Mo interfacial structures and ethoxycarbonyl-functionalized ligands as a catalyst precursor. The activity of supported Rh–Mo catalysts for amide hydrogenation depend on the precursor used, with [(RhCp^E)₄Mo₄O₁₆] showing the highest activity, followed by [(RhCp*)₄Mo₄O₁₆] (Cp* = C₅(CH₃)₅), and then RhCl₃ combined with (NH₄)₆[Mo₇O₂₄]·4H₂O. The catalyst prepared from [(RhCp^E)₄Mo₄O₁₆] effectively hydrogenates tertiary, secondary, and primary amides under mild conditions (0.8 MPa H₂, 353–393 K), demonstrating a high activity and selectivity (conversion: 97%, selectivity: 76%) for primary amide hydrogenation under NH₃-free conditions. Furthermore, we determine that carbonyl oxygen atoms in Cp^E ligands contribute to the electrostatic interaction with Al₂O₃, leading to the high dispersibility of [(RhCp^E)₄Mo₄O₁₆] on the support. We conclude that the high efficiency of [(RhCp^E)₄Mo₄O₁₆] as a catalyst precursor originates from the effective formation of Rh/Mo interfacial active sites, which is assisted by the electrostatic interaction between the Cp^E ligands and support.

Amide hydrogenation is an important process for producing amines, with the development of efficient heterogeneous catalysts relying on the creation of bimetallic active sites where the two components interact synergistically. In this study, we develop a method for preparing catalysts using ligand-functionalized organometallic polyoxometalates by synthesizing a Rh-Mo organometallic polyoxometalate, [(RhCp^E)₄Mo₄O₁₆] (Cp^E = C₅(CH₃)₃(COOC₂H₅)₂), with Rh-O-Mo interfacial structures and ethoxycarbonyl-functionalized ligands as a catalyst precursor. The activity of supported Rh-Mo catalysts for amide hydrogenation depend on the precursor used, with [(RhCp^E)₄Mo₄O₁₆] showing the highest activity, followed by [(RhCp*)₄Mo₄O₁₆] (Cp* = C₅(CH₃)₅), and then RhCl₃ combined with (NH₄)₆[Mo₇O₂₄]·4H₂O. The catalyst prepared from [(RhCp^E)₄Mo₄O₁₆] effectively hydrogenates tertiary, secondary, and primary amides under mild conditions (0.8 MPa H₂, 353-393 K), demonstrating a high activity and selectivity (conversion: 97%, selectivity: 76%) for primary amide hydrogenation under NH₃-free conditions. Furthermore, we determine that carbonyl oxygen atoms in Cp^E ligands contribute to the electrostatic interaction with Al₂O₃, leading to the high dispersibility of [(RhCp^E)₄Mo₄O₁₆] on the support. We conclude that the high efficiency of [(RhCp^E)₄Mo₄O₁₆] as a catalyst precursor originates from the effective formation of Rh/Mo interfacial active sites, which is assisted by the electrostatic interaction between the Cp^E ligands and support.

Herein, we report a novel organometallic series of potent purine-functionalized ferrocene derivatives (PFD) as redox catalysts. The synthesized PFDs were characterized through FTIR, ^H/CNMR, and liquid chromatography–mass spectrometry (LCMS). Their thermogravimetric analysis (TGA) revealed the thermal stability up to 250 °C, and degradation was noted in the range of 300–500 °C. Their catalytic performance was tested and found for oxidative degradation of methyl blue (MB) up to 99% and reductive conversion of trinitrophenol (TNP) into triaminophenol (TAP) up to 92%, which is supported by their band gap analysis (2.7 eV). The highest unoccupied molecular orbital (HUMO) and lowest unoccupied molecular orbital (LUMO) calculations confirmed the stable geometry of PFDs, and negative values of HOMO and LUMO have supported the oxidation and reduction performance of PFDs as they were noted as Vb > Va > Vc > Vd > Ve due functions of variable substitution. The analysis of the Lagergren pseudo-first-order kinetic model, in support of catalytic performance, revealed that the mobility of dye/phenol molecules with the PFD is what regulates the catalytic conversion rate.

Herein, we report a novel organometallic series of potent purine-functionalized ferrocene derivatives (PFD) as redox catalysts. The synthesized PFDs were characterized through FTIR, ^H/CNMR, and liquid chromatography-mass spectrometry (LCMS). Their thermogravimetric analysis (TGA) revealed the thermal stability up to 250 °C, and degradation was noted in the range of 300-500 °C. Their catalytic performance was tested and found for oxidative degradation of methyl blue (MB) up to 99% and reductive conversion of trinitrophenol (TNP) into triaminophenol (TAP) up to 92%, which is supported by their band gap analysis (2.7 eV). The highest unoccupied molecular orbital (HUMO) and lowest unoccupied molecular orbital (LUMO) calculations confirmed the stable geometry of PFDs, and negative values of HOMO and LUMO have supported the oxidation and reduction performance of PFDs as they were noted as Vb > Va > Vc > Vd > Ve due functions of variable substitution. The analysis of the Lagergren pseudo-first-order kinetic model, in support of catalytic performance, revealed that the mobility of dye/phenol molecules with the PFD is what regulates the catalytic conversion rate.