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AgBiO3 is reported for the exclusive oxidation of Am3+ → AmO2+ at near-neutral pH conditions. Literature methods of AmO2+ generation are generally two-step processes; i.e., Am3+ → AmO22+ oxidation followed by AmO22+ → AmO2+ reduction. These methods for Am3+ → AmO2+ oxidation use high temperatures (80–100 °C) and/or several reagents, causing the in situ presence of the AmO2+-complex rather than the AmO2+aq ions. This not only interferes with the much-needed Am–Cm selectivity but also limits the use of AmO2+aq in any other experimental study. The single-step Am3+ → AmO2+ oxidation in the present work using AgBiO3 is done at 25 °C in a non-complexing medium at pH ∼4, making it a first-of-its-kind report. Am–Eu and Am–Cm separation in a single contact, with a separation factor >104, was achieved using the present method, which is unprecedented among aqueous feed solutions. The AmO2+ generated using the present method under non-complexing pH conditions makes it also suitable for exploring the fundamental chemistry of the higher valent americyl ion. A complexation study using the thus-generated AmO2+ ion with acetate ion supports the concept. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of carbon dioxide (CO2) or carbon monoxide (CO) to valuable multi-carbon (C2+) products like acetate is a promising approach for a sustainable energy economy. However, it is still challenging to achieve high activity and selectivity for acetate production, especially in neutral electrolytes. Herein, a bioinspired hemin/Cu hybrid catalyst was developed to enhance the surface *CO coverage for highly efficient electroreduction of CO to acetate fuels. The hemin/Cu electrocatalyst exhibits a remarkable faradaic efficiency of 45.2% for CO-to-acetate electroreduction and a high acetate partial current density of 152.3 mA cm−2. Furthermore, the developed hybrid catalyst can operate stably at 200 mA cm−2 for 14.6 hours, producing concentrated acetate aqueous solutions (0.235 M, 2.1 wt%). The results of in situ Raman spectroscopy and theoretical calculations proved that the Fe–N4 structure of hemin could enhance the CO adsorption and enrich the local concentration of CO, thereby improving C–C coupling for acetate production. In addition, compared to the unmodified Cu catalysts, the Cu catalysts functionalized with cobalt phthalocyanine with a Co–N4 structure also exhibit improved acetate performance, proving the universality of this bioinspired molecule-enhanced strategy. This work paves a new way to designing bioinspired electrolysis systems for producing specific C2+ products from CO2 or CO electroreduction. [ABSTRACT FROM AUTHOR]

A novel synthesis method has been developed for the construction of functionalized 2,4-diarylpyridines. The reaction involves several key processes, including a reduction reaction, Michael reaction, decarboxylation, intramolecular cyclization, oxidation, ring-opening and aromatization reaction. All of these processes are facilitated by heating a mixture of the starting materials in an environmentally benign solvent, propylene carbonate (PC), with the oxidant (air) and the catalyst Cu(OAc)2. This cascade reaction not only forms two new bonds but also cleaves three existing bonds in a single pot. The protocol presented in this study is a valuable tool for synthesizing functionalized unsymmetrical 2,4-diarylpyridines. [ABSTRACT FROM AUTHOR]

Treatment of the Schiff base ligands a–f with Li2[PdCl4]/NaAcO in methanol under reflux gave the single nuclear palladacycles 1a–1f, with the metal atom bonded to a terdentate monoanionic [C,N,S] iminic ligand and to a chloride ligand that completes the palladium coordination sphere. Reaction of 1a–1c with silver perchlorate/triphenylphosphine in acetone at room temperature yielded the single nuclear complexes 2a–2c as the perchlorate salts, after substitution of the chloride ligand by a triphenylphosphine. However, reaction of a–c with Na2[PdCl4]/NaAcO in methanol at room temperature also gave compounds 1a–1c albeit contaminated with small amounts of the corresponding free aldehyde (mixture A). Reaction of mixture A with silver perchlorate/triphenylphosphine in acetone at room temperature gave analogously 2a–2c with some of the corresponding free aldehyde (mixture B). Attempts to purify mixtures A and B via recrystallization produced single crystals of 5 and 6 respectively: two serendipitously formed complexes, bearing thiomethyl aniline and/or acetate ligands, and void of aldehyde or iminic residue; the structures contain eight- and six-membered rings of alternating palladium and nitrogen atoms, respectively. To clarify this situation the aniline itself was reacted with palladium(II) acetate or with Na2[PdCl4]; in the latter case after recrystallization a unique behavior is revealed, giving rise to a tetranuclear complex containing a Pd4N4 ring with three differing coordination environments on the palladium atoms. Treatment of 1d with Ph2PCH2PPh2 (dppm)/AgClO4 or with Ph2PCH2(PPh2)W(CO)5/AgClO4 gave 3d, with a mono-coordinated dppm ligand, and 4d, respectively; complex 3d could not be converted into 4d by reaction with W(CO)5(THF). Recrystallization of 4d gave a still further noticeable species, complex 8: a pentanuclear trans-configured heterometallic mixed valent Pd(II)/W(0) linear complex with the palladium atoms supported by two acetate and two thiomethyl aniline bridging ligands. The complexes were fully characterized by microanalysis, IR, 1H, and 31P NMR spectroscopies, as appropriate. The X-ray single-crystal analyses for compounds 1b, 5, 6, 7 and 8 are described. [ABSTRACT FROM AUTHOR]

To gain mechanistic insights into the acetate-assisted cyclometallations of arylimines promoted by [RuCl2(p-cymene)]2 in polar protic media, DFT geometry optimizations (with M06 and ωB97X-D3 functionals and the cc-pVDZ-PP[Ru] basis set) followed by DLPNO-CCSD(T)/CBS energy evaluations were performed using benzaldimine as a model substrate and methanol as the solvent (with CPCM or SMD models). The calculation results show that coordination of the imine to an acetate ruthenium precursor is followed by anion (chloride or acetate) dissociation as the rate-determining step of the process. H-Bonding of two explicit MeOH to the anion reduces the calculated activation energy to ca. 23 kcal mol−1, in good agreement with the experimental half-life at room temperature. Subsequent AMLA/CMD C–H activation of the intermediate cationic complexes is a faster, reversible process. Alternative reaction pathways involving neutral diacetate ruthenium complexes offer AMLA/CMD transition state structures of lower energy but are precluded due to higher energy barriers for the initial ligand exchange processes at ruthenium. Solvent assistance accelerates the final chloride/acetate exchange processes on the cycloruthenate intermediates, particularly when compression in the condensed phase is taken into consideration. The performance of six DFT functionals (with the aug-pVTZ-PP[Ru] basis set) was assessed using the DLPNO-CCSD(T)/CBS reference energies. Neutral diacetate ruthenium complexes were incorrectly predicted as being kinetically relevant when using hybrid DFT methods (PBE0-D3(BJ), M06-2X or ωB97M-V). Good agreement between the calculated barrier heights and our benchmark energy results was obtained by using double-hybrid DFT methods. PWPB95 with D3(BJ) or D4 dispersion energy corrections was found to be the most accurate (ΔG≠ MUE of ca. 1 kcal mol−1). This study may aid our understanding of and help with further experimental investigations of synthetically useful carboxylate-assisted C–H bond functionalizations involving (N,C)-cyclometallated (p-cymene)Ru(II) intermediate complexes in sustainable polar protic solvents. [ABSTRACT FROM AUTHOR]

The hydrogenation of acetic acid-derived cyclohexyl acetate (CHA) is becoming a safe, efficient and promising route for the production of cyclohexanol (CHOL), an important chemical to produce e-caprolactam. In this work, Cu-Zr catalysts were prepared via different methods for the hydrogenation of CHA. The results showed that a Cu3Zr7-SG catalyst prepared by the sol-gel (SG) method was superior to Cu3Zr7-CP and Cu3Zr7-IM catalysts prepared by the coprecipitation (CP) and impregnation (IM) method, respectively. The Cu3Zr7-SG catalyst showed 97.4% CHA conversion and 95.5% selectivity to CHOL along with 96.3% selectivity to ethanol at 250 1C under 3 MPa of H2. Moreover, the Cu3Zr7-SG catalyst showed a mass specific activity of up to 29.8 gCHA gCu-1 h-1, higher than other Cu-based catalysts under similar conditions. Based on detailed characterization studies, it was found that the larger weak acid sites, more weak and moderate basic sites, higher Cu+/(Cu0 + Cu+) and oxygen vacancies on the surface of the Cu3Zr7-SG catalyst were beneficial for the hydrogenation of CHA. [ABSTRACT FROM AUTHOR]

Puerarin 6′′-O-acetate (P6′′A), a puerarin derivative with a high stability and an improved permeability, exhibits a promising potential in drug development. The large-scale production of P6′′A through green synthesis procedures has never been achieved owing to the low availability of acetyl-CoA. Herein, the enzymatic synthesis of P6′′A in Escherichia coli cell factories overproducing acetyl-CoA has been achieved. Firstly, the effect of three acetyl-CoA-producing pathways on P6′′A conversion in E.coli was compared comprehensively. The pathways containing acetyl-CoA synthetase (ACS) or the pyruvate dehydrogenase (PDH) complex were thereby identified as favorable fluxes yielding more acetyl-CoA. Hence, cells co-expressing ACS and the PDH complex were selected as cell factories overproducing acetyl-CoA owing to the positive cooperativity of ACS and PDH. Subsequently, the maa gene encoding maltose acetyltransferase (MAT) was introduced into these acetyl-CoA-producing cell factories to form engineered strains Q1–Q14. After condition optimization, the engineered strain Q5 got a P6′′A yield of 0.98 g L−1 in M9P-Glc medium supplemented with 2.5 mM puerarin and 1.5% glucose. To further improve P6′′A production, the maa gene in Q5 was replaced by a mutant maaE125N gene to generate another engineered strain (Q15). Microbial production of P6′′A in Q15 was achieved through the centrifuge tube culture, the shake-flask culture and the 6-L reactor culture and the highest P6′′A yield of up to 2.02 g L−1 was obtained in the reactor fermentation. Enzymatically synthesized P6′′A displayed a high stability in human and mouse plasma, a dose-dependent cytotoxicity in HepG2 cells and an improved liposolubility. This research provides a feasible procedure for the green synthesis of puerarin monoesters and lays a foundation for druggability research on P6′′A. [ABSTRACT FROM AUTHOR]

In this work, low-crystalized and defective NiOx/graphene was synthesized by a facile electrolysis-solvothermal method. In the electrolytic process, Ni ions originate from the Ni anode, and graphene is produced from the graphite cathode. Then, Ni ions are reduced into oxides and deposited on graphene in the subsequent solvothermal process. The NiOx/graphene displays excellent electrocatalytic activity and selectivity for ethanol oxidation reaction to acetate. The peak current density was 296.5 mA cm−2 on a glassy carbon electrode. The FE of acetate was more than 93% at the potential range between 1.4 and 1.7 V. We propose that the mechanism is a cooperation between the chemical deprotonating process of ethanol by Ni3+ species and the electrochemical oxidation of the CH3CH2O* intermediate to acetate at the interface between NiOx and graphene. [ABSTRACT FROM AUTHOR]

A dinuclear nickel compound that features vanillin (van) and acetate (OAc) bridging ligands, [Ni2(μ-van)2(μ-OAc)(NCS)3(H2O)]·5H2O 1, was synthesized and characterized using various techniques. Crystal structure analysis revealed a pair of Ni(II) ions bridged by an acetate anion through a μ2-η1:η1 coordination mode. At the same time, vanillin bridges both nickel(II) centers through phenolic oxygen, separating the two Ni ions by a distance of 3.001(7) Å. The temperature-dependent magnetism indicates weak antiferromagnetic behaviour in compound 1, following the Curie–Weiss law with Curie constant C = 1.0145 cm3 K mol−1 and Weiss constant = −4.1 K. Compound 1 was evaluated for its ability to mimic the catechol oxidase enzyme using 3,5-di-tert-butylcatechol as a model substrate with a Kcat value of 157.1 × 102 h−1. Furthermore, compound 1 was tested for its cytotoxicity against HepG2 cancer cells and DNA cleavage properties. [ABSTRACT FROM AUTHOR]

A protocol for efficient N-alkylation of benzamides with alcohols in the presence of cobalt-nanocatalysts is described. Key to the success of this general methodology is the use of highly dispersed cobalt nanoparticles supported on carbon, which are obtained from the pyrolysis of cobalt(II) acetate and o-phenylenediamine as a ligand at suitable temperatures. The catalytic material shows a broad substrate scope and good tolerance to functional groups. Apart from the synthesis of a variety of secondary amides (>45 products), the catalyst allows for the conversion of more challenging aliphatic alcohols and amides, including biobased and macromolecular amides. The practical applicability of the catalyst is underlined by the successful recycling and reusability. [ABSTRACT FROM AUTHOR]

Hybrid phosphines usually combine a phosphine moiety with another heteroatom secondary donor group in their structures while compounds equipped with hydrocarbyl π–donor moieties remain uncommon. This contribution reports the synthesis and structural characterization of the first P/π-allyl-chelating complexes that were obtained using the structurally flexible and redox-active ferrocene unit as the scaffold, viz. [PdCl(R2PfcCHCHCH2-η3:κP)] (1R; R = Ph and cyclohexyl (Cy); fc = ferrocene-1,1′-diyl). These compounds were synthesized from the respective phosphinoferrocene carboxaldehydes R2PfcCHO via reaction with vinylmagnesium bromide to generate 1-(phosphinoferrocenyl)allyl alcohols, which were subsequently acetylated. The resulting allyl acetates reacted smoothly with [Pd2(dba)3]/[Et3NH]Cl (dba = dibenzylideneacetone) to produce the target compounds. Complexes 1R and their nontethered analogues [PdCl(η3-C3H5)(FcPR2-κP)] (5R; Fc = ferrocenyl) were evaluated as pre-catalysts for the Pd-catalysed allylic amination of cinnamyl acetate with aliphatic amines and Suzuki–Miyaura-type cross-coupling of 4-tolylboronic acid with benzoyl chloride. In these reactions, better results were achieved with compounds 5R (particularly with 5Ph), presumably because they form more stable LPd(0)-type catalysts. [ABSTRACT FROM AUTHOR]