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Graphical abstract A high quality of tetramethyl ammonium decatungstate salt (TMADT) is a robust photocatalyst for the visible light-triggered oxidation of inert hydrocarbons by molecular oxygen in MeCN and its activity can be enhanced dramatically under the co-joint action of two additives water and 12 M HCl, originating from that the respective promotion effects of such two additives on photocatalysis can be well joined together. Highlights • The quality of decatungstate salt (DT) is influenced by its quaternary ammonium cations. • A high quality of TMADT can be synthesized directly using tetramthylammonium cations. • TMADT is a robust photocatalyst for visible-triggered oxidation of inert hydrocarbons. • The promoted effects of water and 12 M HCl are magnified in TMADT photocatalysis. • The co-joint action of water and 12 M HCl markedly enhances photocatalytic activity. Abstract Three decatungstates (DTs) were conveniently synthesized respectively using quaternary ammonium cations of tetramethyl, tetrapropyl and tetrabuthyl as counterions (marked as TMADT, TPADT and TBADT) and their quality, photoluminescence (PL) property and redox capacity were measured by UV–vis, XPS and PL spectra and cyclic voltammograms (CVs), respectively. The photo-catalysis activities of three DTs were checked using visible light-driven selective oxidation of cyclohexane, toluene, ethylbenzene and benzyl alcohol by dioxygens (O 2) in acetonitrile (MeCN). The results showed that the photo-catalysis activity of DT anion for these oxidations gradually increases with the shortening of its cationic alkyl chain, which is attributed to the continuous improvement of its quality from TBADT to TMADT. Furthermore, the additives water, 12 M hydrogen chloride (HCl) solution and especially the mixture of both can markedly promote the DTs-photocatalyzed oxidations and such promotion presents an enhancing trend from TBADT to TMADT. which is likely due to the beneficial effects of these additives as follows: i) Water can significantly stabilize the structure of DT anion under light illumination and improve its redox cycling in MeCN; ii) 12 M HCl may obviously improve the oxidative capacity and redox cycling of DT anion and stabilize its photo-excited states. iii) The respective promotion effects of such two additives on photo-catalysis can be well combined and such combined effect is enhanced drastically upon TMADT owing to its hydrophilic feature, thus significantly improving the photo-catalytic efficiency of TMADT under the joint action of water and 12 M HCl. [ABSTRACT FROM AUTHOR]

The development of a mild and highly efficient process for utilization of nitrous oxide (N 2 O) as a green oxidant has very important academic and applied values in the synthesis of oxygenated products. This paper first discloses that a series of vanadium-substituted molybdophosphoric acids (PMo 12− n V n , n = 1–3), assisted by HCl aqueous solution, can efficiently catalyze the visible light-driven liquid phase oxygenation of cyclohexane by N 2 O in acetonitrile (MeCN), providing ca. 26.2% cyclohexane conversion and 90.2% selectivity for cyclohexanol and cyclohexanone (KA oil) under optimized conditions, along with a small quantity of chlorination. Among the catalysts examined, PMo 10 V 2 and especially PMo 9 V 3 showed a higher activity for this photocatalytic oxygenation than PMo 11 V. Furthermore, the amount of water added strongly influenced this HCl-promoted photocatalysis oxygenation. The selectivity of cyclohexanone was continuously and significantly improved from 21.8 to 82.7% with increasing water amount from 0 to 0.15 mL, but the conversion of cyclohexane obviously decreased when the amount of water added was higher than 0.12 mL. The promoting effect of HCl on the present photocatalysis reaction is probably due to the fact that the donor–acceptor (D–A) adduct between HCl and PMo 12− n V n can be excited by visible light to achieve its intra-molecular electron transfer from Cl − to PMo 12− n V n anions, which leads to the generation of Cl radicals and the reduction of catalysts. The subsequent reactions initiated by the Cl radicals result in the oxygenation of cyclohexane by N 2 O to KA oil and the regeneration of catalysts, as supported by UV–vis spectral and cyclic voltammetric measurements. [ABSTRACT FROM AUTHOR]

The development of mild and efficient process for the selective oxygenation of organic compounds by molecular oxygen (O 2 ) can be one of the key technologies for synthesizing oxygenates. Here, the photo-oxygenation of cyclohexane to cyclohexanol and cyclohexanone over tetrabutylammonium decatungstate (W 10 O 32 4− ) was carried out under visible light irradiation and pure O 2 atmosphere. The W 10 O 32 4− was found to be active to this photo-oxygenation in a pure acetonitrile (MeCN), which can achieve ca. 8.1% cyclohexane conversion with ca. 64.3% selectivity for cyclohexanone under sustained visible light irradiation of 12 h. Notably, the above-described photo-catalysis oxygenation was improved to some extent in the presence of some acidic additives such as10 M HCl, H 2 SO 4 , or H 3 PO 4 aqueous solution and benzenesulfonic acid, providing ca . 12.4–14.3% cyclohexane conversion with ca . 59.7–69.4% cyclohexanone selectivity. Moreover, this acid-promoted effect was further magnified in the case of adding a suitable amount of water, which can lead to enhancing conversion (16.8–20.0%) and improving cyclohexanone selectivity (68.2–78.3%). This acidic aqueous solution-promoted effect was also observed upon the W 10 O 32 4− -photocatalyzed oxygenation of other substrates like toluene, ethylbenzene and butanone. This is likely due to the acidic aqueous solutions playing important roles in improving photo-redox cycling of W 10 O 32 4− and preserving its stability, as supported by the UV–vis spectra and cyclic voltammetry measurements. [ABSTRACT FROM AUTHOR]

Highlights: [•] Using more accessible 8-quinolinolato iron(III) (Q3FeIII) complexes to catalyze the selective oxidation of organic compounds by hydrogen peroxide. [•] Important substituent's effect of the Q3FeIII catalyst on their oxidative activity. [•] Significant and outstanding accelerating effect of visible light on the Q3FeIII-catalyzed oxidations. [Copyright &y& Elsevier]

Highlights: [•] Using FeCl3 as efficiently agent or catalyst for photo-chlorination of cyclohexane. [•] Utilization of more accessible visible light. [•] Utilization of more costeffective acetonitrile or acetone as solvent. [•] An excellent selectivity for chlorinated products. [•] The concentrated HCl significantly promotes this photocatalyzed chlorination. [ABSTRACT FROM AUTHOR]

A chlorocuprateionic liquid functionalized biochar sulfonic acid(BCSA–IL-Cu) catalyst was proposed and conveniently preparedvia grafting 1-trimethoxysilyl propyl-3-methyl imidazolium chloride(IL)-CuCl2(IL-Cu) onto biochar sulfonic acid (BCSA). Theproposed catalyst showed much higher turnover numbers (TONs, 3.54for cellulose and 2.42 for bamboo) for the direct hydrolysis of celluloseand especially bamboo in water under microwave irradiation, comparedto the corresponding IL-functionalized BCSA (BCSA–IL, TONs,3.22 for cellulose and 0.46 for bamboo) and BCSA (TONs, 1.51 for celluloseand 0.15 for bamboo). Reducing sugars were the main hydrolysis products,with a concomitant formation of a small amount of 5-hydroxymethylfurfural. This is likely because the BCSA–IL-Cu bearing −IL-Cuand −SO3H groups shows not only a biomimetic delignification(BDL) function, but also a functionality mimicking the cellulose bindingdomain (CBD) and catalysis domain (CD) of cellulose, as supportedby the catalyst’s characterization and reaction results. [ABSTRACT FROM AUTHOR]

The development of a highly efficient and environmentally friendly process for the hydrolysis of cellulose into reducing sugars could be one of the key technologies for large-scale use of cellulosic biomass in the future. In order to pursue this goal, an ionic liquid (IL)-grafting biochar sulfonic acid catalyst (BC-SO3H-IL) was proposed and conveniently prepared with bamboo powder as a carbon resource and 1-(trimethoxy propyl silane)-3-methyl imidazolium chloride as the IL. Its catalytic performance for the heterogeneous hydrolysis of cellulose and bamboo was checked under microwave irradiation. The designed BC-SO3H-IL catalyst was found to show much higher turnover number (TON, 3.22–6.23 for cellulose and 0.26–2.53 for bamboo) and excellent repeatability for this hydrolysis compared to the corresponding biochar sulfonic acid (BC-SO3H, TON, 1.51–1.81 for cellulose and 0.14–1.33 for bamboo). This is likely to be because the IL groups flexibly joined to biochar sulfonic acid, like cellulose binding domain (CBD) of cellulase, efficiently breaks in the hydrogen bonding network of cellulose molecules. On the other hand, they probably play a harmonious role in the SO3H groups (as a catalysis domain (CD) of cellulase) catalyzing cleavage of the β-1,4 glycosidic bonds of cellulose, as supported by TGA characterization and catalytic reaction results. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of ethylbenzene with 30% aqueous hydrogen peroxide (H2O2) in an acetone–water medium at 30°C was investigated using hexadentate 8-quinolinolato manganese(III) complexes (Q3MnIII) as catalysts. The results indicated that the Q3MnIII complexes, with ammonium acetate and acetic acid as additives, selectively catalyzed the side chain oxidation of ethylbenzene at secondary carbon atoms, affording acetophenone as a major product. Among the Q3MnIII complexes examined, the 5,7-dibrominated Q3MnIII catalyst was the most active, and provided the ethylbenzene conversion of 26.1% and the oxidation yield of 65% under the optimum conditions. The influence of various parameters on the reaction was checked in detail. Based on the UV–vis spectra, a free radical mechanism for the Q3MnIII catalytic system was also proposed. [ABSTRACT FROM AUTHOR]

Abstract: Hexadentate 8-quinolinolato manganese(III) complexes (Q3MnIII) developed by us, with the help of NH4OAC and HOAc, were found to efficiently catalyze the mild oxidation of thioanisole with aqueous hydrogen peroxide in environmentally benign acetone–water media. The ligand''s halogen substituents could improve the catalytic efficiency of Q3MnIII complexes, and this is likely that they can strengthen the distorted effect of Q3MnIII, as supported by B3LYP/6-311G (d) calculation. The adjusting effect of additives on this sulfoxidation was also investigated and their mediation mechanisms were proposed. [Copyright &y& Elsevier]

Abstract: A series of hexadentate 8-quinolinolato manganese(III) complexes were synthesized and proven to own a distorted octahedral geometry via elemental analysis, solid UV–vis spectroscopy and Hartree–Fock/3-21G+ calculation. These Mn(III) complexes were found to be more efficient than their corresponding tetradentate 8-quinolinolato manganese(II) and salen-MnIIIOAc for the oxidation of alcohols in acetone medium, being due to their special hexadentate binding structures that could open an axial Mn form the more active pentadentate structures in the presence of aqueous hydrogen peroxide, as supported by UV–vis spectra. The halogen substituents in ligand''s aryl ring could significantly enhance the catalytic activities and 5-chloro-7-iodo-8-quinolinolato manganese(III) gave the highest turnover number (TON). A reasonable mechanism for the present catalytic system was proposed. [Copyright &y& Elsevier]

Abstract: It was reported that the microwave-assisted in situ synthesis and encapsulation of Mn(III)–Salen complexes inside the pores of the amino-functionalized mesoporous silicas of HMS. The prepared heterogeneous Mn(III)–Salen complexes via this method were characterized by diffusion reflection UV–Vis, FT-IR, TG-DTA and N2 volumetric adsorption, and their catalytic properties were checked with the epoxidation of trans-stilbene with iodobenzene diacetate. The results indicated that, in comparison with the traditional adsorption method, the microwave-assisted approach was efficient and environmental-friendly, and could improve the loadings of Mn(III)–Salen complexes on HMS via a strengthening axial coordination of the surface’s NH2 groups of HMS toward the Mn(III)–Salen complexes. Furthermore, the encapsulation of Mn(III)–Salen complexes inside the host HMS could be rapidly achieved by the HMS’s porous outlets grafting a suitable molecular-size ester-terminated polyamidoester dendrimers under the microwave irradiation. As a result, the encapsulated Mn(III)–Salen complexes inside the HMS’s pores showed a lower leaching, better catalytic activity and reusability than the un-encapsulated counterparts in catalyzing the epoxidation of trans-stilbene. [Copyright &y& Elsevier]

A coupled process, of which Pd/γ-Al2O3–NH4VO3 catalyzed the hydroxylation of benzene with hydrogen peroxide produced in situ by an anthraquinone (AQ) redox route, was carried out via a sealed gaseous inner-circulated device under the atmospheric pressure. By means of such process, 0.57% of benzene conversion, 100% of phenol selectivity and 26.6% of anthraquinone-utilized efficiency were achieved upon the mixed Pd/γ-Al2O3–NH4VO3 (V/Pd molar ratio for 4) in the presence of benzene/acetic acid (4v/10v). Above all, after the coupled reaction system was recycled three times, the accumulated phenol amount could achieve ca. 0.833 mmol and its average value (ca. 0.278 mmol) was slightly higher than phenol amount obtained in the first run (ca. 0.255 mmol), indicating that such coupled reaction system could be recycled efficiently. In addition, a synergistic mechanism was proposed to explain the favorable effect of V compound on the Pd/γ-Al2O3 catalyst. [ABSTRACT FROM AUTHOR]

A series of novel non-salicylaldehyde based Salen ligands have been synthesized from the condensation of dialdehyde or diketone with o-aminophenol and the corresponding manganese(III) complexes prepared by further coordination of them with $${\hbox{Mn(OAc)}_{2}\cdot 2\hbox{H}_{2}\hbox{O}}$$ . FT-IR, UV–Vis spectra, chemical analysis and the structure optimized by Hartree-Fork/3-21G+ all indicated that the qualities of these novel Mn complexes were relative to their molecular structures. More specifically, glyoxal based Mn complex 2c, which was similar to the traditional Mn(III)-salicylethylenediamine, had a short carbon chain and non geometrical constraint of the aliphatic bridge in the two o-aminophenol, and its quality was the best when compared to glutaraldehyde, 2,4-pentanedione and 1,3-cyclohexanedione based Salen Mn(III) complexes (3c, 4c and 5c). And it was also the excellent catalyst for the epoxidations of several non-functionalized alkenes with molecular oxygen/sacrificial-isobutyaldehyde, PhI(OAc)2 or H2O2 as oxidant. [ABSTRACT FROM AUTHOR]

Abstract: It was first discovered that a novel micro-emulsion system, which was made of water, benzene, acetic acid, sodium dodecylbenzene sulfonate as a surfactant and ferric dodecane sulfonate as a catalyst, was very efficient for hydroxylation of benzene to phenol with hydrogen peroxide (H2O2) as an oxidant under mild reaction conditions. By use of this micro-emulsion system, the excellent selectivity for phenol (92.9%), the utilization efficiency of H2O2 (93.1%) and the efficient recycling utilization of the catalyst and un-reacted benzene could be realized at the same time. [Copyright &y& Elsevier]

Abstract: It is firstly discovered that ZnCl2 modified γ-Al2O3 solid Lewis acidic catalysts (ZnCl2/γ-Al2O3), which are prepared by solid-state reaction, are very active and extremely selective for the preparation of guaiacol by the vapor phase O-methylation of catechol with methanol in a fixed-bed reactor at 553K, under the optimum reaction conditions, the conversion of catechol and the selectivity for guaiacol are up to 81.8 and 90.9%, respectively over ZnCl2 (10%)/γ-Al2O3 and by far better than the reaction results over the solid Brønsted acid catalyst (HY), proposing that the weak coordination of catechol with the Zn2+ sites of ZnCl2/γ-Al2O3 plays a key impact on the high selectivity for guaiacol. The recycling tests indicate that the modification of ZnCl2 could significantly improve the catalytic stability of γ-Al2O3 by it efficiently restraining the catalyst''s coking. And the deactivation of ZnCl2/γ-Al2O3 is mainly caused by its ZnCl2 leaching and surface coking in the run procedure, therefore its catalytic activity can be only partly recovered by the calcination in air at 773K for 4h. [Copyright &y& Elsevier]

Three types of HMS supports, which were as-synthesized, HMS(u), HMS(c) calcined from HMS(u), and HMS(m) prepared by the modification of HMS(c) with 3-amino propyltriethoxysilane, were first used to assemble the Ti catalytic sites through the exchange reactions between them and Ti compounds such as Ti tetraisoproxide (Ti(OiPr)4), Ti tetrachloride (TiCl4)) and their Ti tartrate complexes. The Ti-assembled HMS catalysts were investigated in detail by means of FT-IR, UV–vis reflection spectra, chemical and elemental analyses. It is found that in Ti(OiPr4 and especially TiCl4, the exchange that takes place with the surface hydroxyls of the HMS(c) is easier than with the surface NH2 groups of HMS(u) and HMS(m). Ti tartrate complex can be successfully assembled on the HMS(c) through three assembled pathways. The UV–vis reflection spectra indicates that the Ti species are highly dispersed upon the surface of HMS. In catalyzing epoxidation of styrene with TBHP, the above-described catalysts show a higher catalytic activity and selectivity for the epoxides than unloading Ti tartrate complex, and the Ti-substituted HMS catalysts. Their outstanding advantage is that they can be reused many times with little loss of activity. [ABSTRACT FROM AUTHOR]

Di-halogenated 8-quinolinolato ironIII complexes can be activated by boron and fluorine doped carbon nitride to enhance its visible light catalysis rate for the oxidation of cyclohexane to cyclohexanol and cyclohexanone by H 2 O 2. • C 3 N 4 BF as additive can remarkably enhance FeIIIQ 3 -photocatalyzed oxidation efficiency. • Compact connection between two compounds facilitated electrons transfer and induced a weak structure distortion of catalyst. • Highly selective oxidation of cyclohexane to KA oil was achieved under visible light illumination and mild condition. This paper discloses that boron and fluorine-doped carbon nitride (C 3 N 4 BF), as a solid activator, can efficiently accelerate the relatively inert 5,7-dichloro-8-quinolinolato iron(III) complex (FeIII(Q b) 3) to photo-catalyze the oxidation of cyclohexane to cyclohexanol and cyclohexanone by hydrogen peroxide (H 2 O 2) in acetonitrile (MeCN) under visible light irradiation and achieve 25.87 % cyclohexane conversion, which is almost twice as high as without it and obviously higher than the results obtained using ordinary C 3 N 4 as an activator or under thermo-catalysis. Furthermore, its such activation effect on FeIII(Q b) 3 photocatalysis is also observed in the H 2 O 2 -involved oxidation of other substrates such as toluene, ethylbenzene, benzyl alcohol and thioanisole. UV–vis and PL spectra, photocurrent transient measurements and theoretical calculations support that C 3 N 4 and especially C 3 N 4 BF can form strong π-π stacking interactions with FeIII(Q b) 3 , thus inducing a weakly structural distortion of FeIII(Q b) 3 and enhancing its photo-reductive activation via capturing the photo-generated electrons of the activator. As a result, the synergistic catalytic effect of FeIII(Q b) 3 with C 3 N 4 /especillly C 3 N 4 BF can significantly accelerate the above thermo-/especially photo-oxidations. [ABSTRACT FROM AUTHOR]

MoO42−-H2O2 is an efficient oxidation system for the conversion of para-alkyl-phenols to high value-added para-peroxyquinols and para-quinols, but its large-scale application is still limited to difficulty in catalyst recovery. This paper discloses that a hydrated calcium silicate (CS)-supported calcium molybdate (CM) catalyst (CMS) is easily fabricated in high-yield and large-scale by simple coprecipitation. Compared to the unsupported CM and Na2MoO4, CMS has an enhanced catalytic activity for the selective oxidation of para-alkyl-phenols, but also it shows a drastically improved selectivity for the target products, which can achieve 84% conversion and 100% selectivity for the goal products in catalyzing the oxidation of 2,4-xylenol with H2O2 in water. Also, it is very efficient for the selective oxidation of other p-alkyl substituted phenols in water or methanol, especially including the highly selective oxidation of p-cresol which is easy to be overoxidized. More importantly, the CMS catalytic system can be conveniently recovered and repeatedly run without significant activity loss, showing a good reusability. In situ UV-DRS and FT-IR spectra, as well as H2O2 decomposition experiments support that the alkaline CS carrier can induce the reaction of CMS with H2O2 to preferentially generate the mono-/di-peroxomolybdates as the key species for the selective oxidation of para-alkyl-phenols. [ABSTRACT FROM AUTHOR]

The formation of photoactive species in the Keggin-type XPMo 12-n V n O 40 polyoxometalates (POMs, n = 1-3, X = H + , tetramethyl (TMA). tetrabutyl (TBA) or cetyltrimethyl (CTMA) ammonium cation (Q + ))-HCl system was researched in details by UV–vis and its photo-catalysis performance evaluated via the oxidation of cyclohexane by dioxygens (O 2 ) in acetonitrile (MeCN) under visible light irradiation The results showed that the V V -O-M (M for V V or Mo IV ) sites of POM can capture HCl to form a protonated photoactive species (PA, POM-(V V OHM) + Cl − ) and the solvent MeCN likely participates the formation of such PA species via weak coordination. This PA species, with a characteristic absorption band of 475 nm, a 51 V-NMR chemical shift of −550 ppm and an oxidative potential of higher than 0.9 V, should be responsible for the present photo-catalysis oxidation. The formation of PA species was accelerated significantly with increasing the V atoms incorporated into POMs, but hampered seriously in the presence of slight excess water due to the replaced effect of water for the coordinated HCl and MeCN. Notably, such impediment effect of water was weakened obviously over the Q + -containing POMs due to a hydrophobicity of these POM's. As a result, most of the Q + -containing POMs showed a higher activity for this photo-catalysis reaction in MeCN-HCl-H 2 O media than the H + -containing counterparts. Isotope tracing test of water-containing heavy oxygen 18 O (97%) in photo-catalysis reaction indicated that the oxygen atoms in water had partly contribution to the formation of cyclohexanol (ca.8.2%) and especially cyclohexanone (ca. 33.3%), which can drastically restrain chlorinated side reactions and thus improve cyclohexanone selectivity. Based on these findings, a free-radical mechanism initiated by the Cl atoms generated in the excited POM-(V V OHM) + Cl − species was proposed. [ABSTRACT FROM AUTHOR]

Graphitic phase carbon nitride (CN) is a safe and green photocatalyst, but the activity of the pristine CN photocatalyst is still unsatisfactory due to the significant recombination of photogenerated charges, so it is still challenging to realize the practical application of CN for photocatalysis. Herein, we report that a mechanical mixture consisting of pre-thermally polymerized melamine (Me) and 3-amino-1,2,4-triazole (AT) can be transformed into a crystalline isotype heterojunction material (ISCN MT) by ionothermal synthesis. A series of characterizations and photocatalytic tests demonstrate that the polymerizability, porosity and photoelectric conversion efficiency of the constructed ISCN MT have been improved. The photogenerated charge pairs of the ISCN MT can migrate in S-scheme, indicating that ISCN MT retains the strongest reduction capacity and greatly improving the separation efficiency of photogenerated charge pairs. As a result, the ISCN MT exhibits outstanding performance. Its catalytic efficiency for visible light-triggered hydrogen evolution from water can reach 9.64 mmol·g−1·h−1 with an apparent quantum efficiency (AQE) of 26.23%, which is 21 or 45 times higher than that of the carbon nitride material directly polymerized by Me or AT (CNM or CN T). In addition, the ISCN MT has a catalytic efficiency of 15.64 μmol·g−1·h−1 for photocatalysis CO 2 reduction under water vapor. This work provides a facile pathway for designing S-scheme isotype heterojunction CN-based photocatalysts for the efficient conversion of solar energy. [Display omitted] • S-scheme carbon nitride isotype heterojunction ISCN MT were prepared by an in-stu ionothermal synthesis method. • Ionothermal synthesis method can significantly improve the crystallinity of material. • ISCN MT showed excellent activity for photocatalytic H 2 evolution (9.64 mmol·g−1·h−1) and CO 2 reduction (15.64 μmol·g−1·h−1). • The exciton dynamics was analyzed in detail using TAS to prove the existence of a strong built-in electric field. [ABSTRACT FROM AUTHOR]

This paper discloses that the oxygenation of cyclohexane by dioxygen (O2) to cyclohexanol and cyclohexanone over three vanadium-substituted tungstophosphoric acids (PW11V1, PW10V2, PW9V3) can occur in MeCN under visible-light irradiation, but provides very low cyclohexane conversion (0.8-2.4 %) with modest cyclohexanone selectivity (51-58.3 %). Importantly, an HCl aqueous solution was found to drastically promote this photooxygenation catalyzed by PW10V2 and especially PW9V3 acids, respectively providing approximately 20.4 and 23.4 % cyclohexane conversion and approximately 82.5 and 87.1 % cyclohexanone selectivity, with a concomitant formation of a small amount of chlorocyclohexane. However, such promoting effect was negligible in the PW11V1- photocatalyzed oxygenation and the other acids and the chlorine-containing salts did not show any promotion effect on the present photocatalysis reaction. Notably, the HCl-promoted photocatalytic oxygenation was significantly influenced by the amount of water. The cyclohexanone selectivity continuously and significantly increased with water amount, but photooxygenation efficiency drastically decreased if a slight excess amount of water was added. Based on these findings and the UV/Vis spectral and cyclic voltammetric measurements, a free-radical mechanism initiated by the Cl atoms generated in the present photocatalysis system was proposed. [ABSTRACT FROM AUTHOR]

The advanced coupled conversion technique based on the oxidative dehydrogenation (ODH) of alcohols and the reduction of CO2 is a potential strategy to solve the current energy and environmental crisis, and is of great significance for the upgrading conversion of CO2 to fuels. This work discloses that the Al3+ species-doped decatungstates (Al-DTs) can efficiently catalyze the coupled conversion of various aliphatic and aromatic primary/secondary alcohols with CO2 in MeCN under visible light illumination and very mild conditions, and the reductive efficiency of CO2 depends on the doping levels of Al3+ species in Al-DTs and the ODH reactivity of alcohols. After continuously illuminating for 12 h, the best, 4% Al-DT can provide 437 μmol acetophenone as the ODH product and 218 μmol CO2 reduction products (formic acid and methanol) with 1.82 h−1 turnover frequency in the photocatalytic coupled conversion of α-phenylethanol with CO2. Also, a trace amount of CO is detected from the photocatalytic coupled reactions. UV-vis spectra and isotope tracing tests using heavy oxygen water (H218O) support that the doubly-reduced blue H2DT species generated from the photocatalytic ODH of alcohols turns into its oxygen-deficient form ([DT2−]v) via an intra-molecular dehydration or lattice oxygen transfer and the latter, with the help of doped Al3+ species, may efficiently reduce CO2 to fuels via the multi-step proton-coupled electron transfer (PET) pathway. [ABSTRACT FROM AUTHOR]

Methylsulfonylmethane (MSM) is a newly discovered human nutrient that has significant health care and therapeutic function. In this work, we developed a new type of catalyst-free air oxidation of dimethyl sulfoxide (DMSO) to MSM under relatively mild conditions based on the mechanism of isopropylphenyl free radicals (R·) activating molecular oxygen (O2) generating reactive oxygen species (ROS). Experimental results showed that cumene as a solvent, due to its active tertiary sp3 C–H bond, promotes the efficient catalyst-free air oxidation of DMSO to MSM under relatively mild optimized conditions. Based on the quenching test of free radicals and theoretical calculation of the activation energies of two oxidation pathways of isopropylphenyl peroxy radicals (ROO·) and cumene hydroperoxide (CHP), it has been demonstrated that ROS in this reaction is mainly ROO· and hydroxyl radicals (HO·). Furthermore, we proposed a possible catalyst-free air oxidation mechanism. This work provided a simple and cost-efficient approach for the green synthesis of MSM. [ABSTRACT FROM AUTHOR]

Summary: Oxidation of organic sulfides is a significant reaction due to its application in many fields. Herein, we have developed a novel catalyst-free oxidation of organic sulfides by O2 under relatively mild conditions. The choice of the procedure was based on the well-acknowledged reactivity of the active C(sp3)-H bond of organic compounds to form the corresponding alkyl carbon free radicals (R•) in the presence of O2. The results showed that hydrocarbons such as tetrahydronaphthalene (THN) and cumene possessing the active C(sp3)-H bonds due to their lower bond dissociation energy (BDE), as a solvent, markedly promoted this catalyst-free sulfoxidation. It has been proved that reactive oxygen species (ROS) in this reaction are alkyl-peroxide radicals that are produced from R•, which is derived from the homolytic cleavage of the active C(sp3)-H bond with the help of heating and dioxygen, and further its activation of molecular oxygen. On this basis, combined with the DFT calculation of the activation energy of two reaction pathways, a possible reaction mechanism is proposed. The work provided a green synthesis approach of sulfoxide and sulfone compounds, and a scientific basis for a green process of ultra-deep desulfurization of fuel oils. [ABSTRACT FROM AUTHOR]

Abstract: The development of mild and efficient process for the selective oxidation of organic compounds with molecular oxygen can be one of the key technologies for synthesizing oxygenates. Here, a visible light-driven metal chloride to catalyze the selective oxidation of cyclohexane was carried out at ambient temperature under a pure O2 atmosphere. Among the metal salts examined, only a few metal chlorides, with easily changeable valence, such as CuCl2·2H2O, VOCl3, and FeCl3·6H2O, were found to be active to this photo-oxidation reaction in acetonitrile or acetone, providing cyclohexanol, cyclohexanone, chlorocyclohexane, and cyclohexene as main products. This is likely because the weak coordination of these metal chlorides with solvent molecules plays key roles in absorbing visible light and realizing photoredox cycle, as supported by UV–Vis spectrum and cyclic voltammetry measurements. Among these active metal chlorides, CuCl2·2H2O showed a higher conversion and better selectivity for cyclohexanol and cyclohexanone (the oxygenated products) than the other two metal chlorides, and its activity and selectivity for chlorocyclohexane were significantly improved in the case of adding concentrated HCl, because HCl promotes the photocatalytic cycling, as supported by UV–Vis spectra. Notably, a high turnover frequency (TOF, 7.4h−1) and an excellent selectivity for the oxygenated products (93%) were achieved upon a low concentration of CuCl2·2H2O (0.002molL−1), 0.1ml of concentrated HCl and 2atm of O2 pressure. Based on these findings, a free radical mechanism for the present photocatalysis system was proposed. [Copyright &y& Elsevier]

Abstract: Novel hexadentate binding 8-quinolinolato manganese(III) complexes were proposed and conveniently synthesized for the epoxidation of olefins with aqueous hydrogen peroxide in water–acetone media with ammonium acetate and acetic acid as additives. The catalytic efficiencies of the suggested catalysts were found to be obviously superior to the traditional tetradentate salen–MnIIICl, due to their special hexadentate binding structures that could be easily converted to the corresponding pentadentate with pendant hydroxyl groups by opening an axial Mn the reaction media, as supported by UV–vis spectra, in situ cyclic voltammetry, and quartz crystal microbalance characterizations. [Copyright &y& Elsevier]

This paper reports that the optical properties of anthraquinone (AQ) and its photo-catalytic performance in the visible light-driven p -xylene (PX) oxidation can be fine-tuned and improved through varying its skeleton substituents at the molecular level, and the electron-withdrawing substituent exhibits a better improvement effect than the electron-donating one. The best catalyst 2-carboxyanthraquinone (AQ-COOH) can achieve 70.9% PX conversion and 88.2% p -toluic acid selectivity under visible light illumination and 1 atm O 2 pressure. The addition of benzenesulfonic acid in the above photocatalytic system can further increase PX conversion to 86.7%, along with a significant improvement in the selectivity of p -carboxybenzaldehyde and terephthalic acid, which likely originates from the unique recombination behavior of the photo-generated charge carriers of the catalyst and the additive driven by the strong interactions between their aromatic skeletons and acidic substituents. Furthermore, AQ-COOH can achieve almost quantitative yield of acetylacetone in ethylbenzene photooxidation and the regulating effect of toluene's para-position substituents on its reactivity is also reported in the AQ-COOH photocatalysis system. Based on quenching tests and EPR spectral characterizations, the oxygen vacancies (h+), superoxide free radicals (O 2 •-) and singlet oxygen (1O 2) as the photo-generated active species are involved in the proposed photo-catalysis mechanism. [Display omitted] • AQs-based photo-catalytic protocol is very efficient for PX oxidation to p -TA. • This protocol uses inexpensive visible light and O 2 /air as green reactants. • This protocol employs mild reaction conditions and its operating is very simple. • This protocol has a good adaptability for the photooxidation of other substituted toluene. • Photosensitive PhSO 3 H plays a unique adjusting effect in this photo-catalytic protocol. [ABSTRACT FROM AUTHOR]

This article reveals that molybdenum (Mo) heteroatoms isomorphously substituted decatungstates (Mo–DTs) can be conveniently synthesized via copolymerization of tungstate and molybdate in acidic solution. A series of characterizations support that the incorporated Mo heteroatoms play crucial roles in improving the redox capacity and visible light harvesting efficiency of Mo–DTs, especially the photo‐excited probability and lifetimes, so that the novel Mo–DTs exhibit a remarkably enhanced photo‐catalytic efficiency in the visible‐light‐triggered selective oxidation of inert hydrocarbons by O2 under mild conditions. In the photo‐oxidation of cyclohexane under continuous visible light irradiation for 30 h, the best 1 % Mo–DT can achieve 44.8 % conversion and 89.7 % cyclohexanone selectivity in the presence of 2 M HCl, and the regenerated catalyst after simple hydrothermal treatment has excellent reusability. This is the first successful example of incorporating Mo atoms into the skeleton of non‐lacunary DTs, which has special significance for expanding the application of DTs in visible‐light‐catalysis. [ABSTRACT FROM AUTHOR]

Zr-Based catalysts have been extensively applied in Meerwein–Ponndorf–Verley type catalytic transfer hydrogenation (CTH) reactions, but they are easily deactivated in the CTH conversion of high concentrations of levulinic acid (LA) to γ-valerolactone (γ-GVL). This work discloses that by using cheap glucose and ZrCl4 as two main raw materials, glucose phosphate carbamide zirconium (GluPC-Zr) is easily synthesized at large scale and low cost via a simple two-step conversion. The constructed GluPC-Zr has enhanced Lewis acid–base properties and good porosity, thus exhibiting outstanding activity for the CTH reactions of LA or its esters with isopropanol (IPA), providing 95–98% γ-GVL yields. Because of the excellent esterification performance of the introduced acidic phosphate groups, GluPC-Zr also works well at high LA concentrations, achieving a much higher turnover frequency (TOF, 8.2 mmol γ-GVL per g catalyst per h) than previously reported Zr-based catalysts (TOF, 0.2–2.4). And it shows excellent reusability in the reaction of LA with IPA, still providing ca. 95% γ-GVL yield after the seventh cycle run. This work provides a preferential esterification strategy for LA to hamper catalyst deactivation, which is of special significance for the large-scale production of γ-GVL from biomass-derived LA and a low-cost GluPC-Zr catalyst. [ABSTRACT FROM AUTHOR]

• An effective strategy is developed to successfully fabricate CQD-hybridized TBADT. • CQD hybridization slightly improves the quality and redox capacity of TBADT. • CQD hybridization enhances visible light use and photoexcited state lifetime of TBADT. • CQD hybridization significantly enhances photocatalyic oxidation performance of TBADT. • The favorable hybridizing effects of CQD on TBADT are magnified by 2 M HCl solution. This paper discloses an efficient strategy for the preparation of carbon quantum dot (CQD)- hybridized (nBu 4 N) 4 W 10 O 32 (TBADT). A key step in this strategy is to hydrothermally treat CQD with TBABr solution to form the TBA+ micelle-encapsulated CQD, which acts as a cationized hybridizer to combine with the W 10 O 32 4− anion to yield the target catalyst. XPS, UV–vis, PL and CV characterizations indicated that CQD hybridizer plays unique roles in improving the structural stability, redox capacity and visible light response of TBADT, especially in enhancing the stability of its photo-excited state. In the visible light-triggered selective oxidation of cyclohexane, toluene, ethylbenzene and benzyl alcohol with dioxygens in acetonitrile, the optimized hybrid containing 3% CQD shows much higher photo-catalytic activity than pure TBADT, affording ca. 21.7% conversion and 84.8% cyclohexanone selectivity in cyclohexane photo-oxidation, Additionally, the additive 2 M HCl further enhances the above hybridization effects, thereby significantly promoting the current photo-catalytic oxidations. [ABSTRACT FROM AUTHOR]

para-Xylene (PX) is a basic building block of polyethylene terephthalate, which is currently produced from petroleum resources. Developing a renewable route to PX is highly desirable to address both economic and environmental concerns. Several attempts used noble metal catalysts, e.g. Pd/Al2O3, to synthesize PX from biomass-derived 4-methyl-3-cyclohexene-1-carboxaldehyde (4-MCHCA), but suffered from a severe decarbonylation reaction, resulting in toluene as the main product. In this paper, we report an FeOx modification strategy to suppress the decarbonylation reaction on a Pd/Al2O3 catalyst, leading to a drastic shift in selectivity towards PX with a yield up to 81% via a cascade dehydroaromatization–hydrodeoxygenation (DHA–HDO) pathway. Characterization and control experiments revealed that the electron density of Pd sites decreased in an FeOx-modified Pd/Al2O3 catalyst compared to Pd/Al2O3, thus tuning the preferential adsorption mode of the substrate from η2-(C,O), the key transition state of the decarbonylation reaction, to the η1-(O) mode that favors the hydrodeoxygenation process. Notably, this designed catalyst is highly stable and is readily applicable in the selective synthesis of a broad range of desired aromatic chemicals via the same DHA–HDO pathway from cyclohex-3-enecarbaldehyde derivatives. Overall, this work develops a controllable catalyst modification strategy that tailors an efficient catalyst for petroleum-independent bio-PX synthesis. [ABSTRACT FROM AUTHOR]

In this work a series of bamboo-derived biochars rich in micropores (its micropore ratio as high as 76%) were prepared by ZnCl 2 chemical activation of bamboo processing residues, further modified with oxidation using concentrated HNO 3 , and characterized by N 2 adsorption, XRD, Raman spectra, elemental analysis and Boehm titration. Their adsorptive desulfurization (ADS) performances were examined using dibenzothiophene from model fuels as an adsorbate. The results showed that the pore structure properties of these biochars are dominated by ZnCl 2 chemical activation, the graphitization degrees are mainly governed by activation temperature, and the significantly increased surface acidic groups are primarily contributed from the HNO 3 oxidation treatment. The biochar’s abundant micropore characteristic is an indispensable prerequisite for its good ADS performance, and also its high graphitization degree and surface acidic groups play important roles in improving ADS performance. Meanwhile, the optimized biochar can achieve an sulfur removal (%) of 96% with a selectivity close to 96%, its maximum adsorption amount and its breakthrough capacity reach 38.4 mg-S/g and 9.5 mg-S/g, respectively, and it shows much superior ADS performance to commercial activated carbon (AC) used in this work. Furthermore, the biochar can be reused for three times after regeneration without significant loss of ADS capacity. Thus, the biochar may become an excellent ADS adsorbent for production of clean fuel oils. [ABSTRACT FROM AUTHOR]

Amphiphilic [C 12 mim]Cl and AAIL [C 4 mim][Cys] improved the reactivity and reusability of nano/submicroscale MOFs owing to the synergistic effects of IL - containing nano/submicro-structures constructed in-situ. [Display omitted] • Nano/submicroscale MOFs with meso- or macropores were built via simple linkers. • IL-assisted conversion of anethole over nano/submicroscale MOFs was developed. • [C 12 mim]Cl and [C 4 mim][Cys] improved the reactivity and reusability of MOFs. • Synergistic effects between IL and Cu-BTC-1 or Fe(PMA) were well characterized. A synergistic strategy involving ionic liquid (IL) and Cu- or Fe-based metal-organic frameworks (MOFs) has been developed for the selective oxidation of anethole with H 2 O 2 and tert -butyl hydroperoxide (TBHP). Under the optimum conditions, 74.8%–91.5% conversion of substrate and 92.1%–94.6% selectivity for anisaldehyde were obtained over Cu-BTC-1 (BTC : benzene-1,3,5-tricarboxylate) with the aid of 5.0 mol% [C 12 mim]Cl using aqueous H 2 O 2 as the oxygen source. In contrast, Fe(PMA) (PMA : pyromellitate) nanorods provided up to 84.0% yield of 4-methoxyphenylacetone in the presence of 5.0 mol% [C 4 mim][Cys] by using TBHP oxidant. Notably, amphiphilic [C 12 mim]Cl and multifunctional [C 4 mim][Cys] are favorable for the improved reactivity and good reusability of Cu-BTC-1 or Fe(PMA) owing to the synergistic effects of Cu-BTC-1/ [C 12 mim]Cl or Fe(PMA)/ [C 4 mim][Cys] nano/submicro-structures fabricated in-situ. In particular, nanoscale stacking of [C 4 mim][Cys] on Fe(PMA) can be directly demonstrated by TEM. In-depth understanding of the reaction mechanism can be achieved using XRD, FT-IR, DRUV-vis and UV–vis techniques. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructed crystalline carbon nitride nanosheets by integrated strategy of spatially restricted growth and hydrochloric acid induced exfoliation. • K+ was revealed to help the formation of ultra-long-lived and highly reactive radicals. • Grabbing and storing electrons enhances the dissociation of excitons, thus greatly improving the photocatalytic performance. • The photocatalytic hydrogen evolution rate by modified carbon nitride is 49 times higher than that of ordinary ones, and the AQE can reach 27.79%. Two-dimensional carbon nitride nanosheets continue to attract attention in photocatalysis, but inefficient exciton dissociation and charge separation limit further improvement of their photocatalytic performance. Herein, we have prepared highly crystalline carbon nitride sheets using a integrated strategy of spatially restricted growth in solid salt media and hydrochloric acid induced exfoliation. In the confined space of the solid salt, K+ induce the ordered growth of carbon nitride and diffuse into the carbon nitride bulk phase with thermodynamically feasible paths. Pickling was also found to control the K+ concentration gradient distribution and regulate the charge characteristic of cyanoamino, thereby controlling the quantity and activity of trapped long-lived electrons. The storage free electron behavior of carbon nitride dual-functionalized with cyanoamino and K+ (KCCN) greatly facilitates the dissociation of excitons, resulting in photocatalytic hydrogen evolution efficiency of 10.78 mmol·g−1·h−1, which was 49 times higher than that of ordinary carbon nitride. KCCN had a hydrogen production quantum efficiency of 27.79%, higher than the majority of the similar materials reported. This study provides new insights into the design of more excellent carbon nitride-based photocatalysts through exciton engineering. [ABSTRACT FROM AUTHOR]

A series of Fe 2 O 3 doped SBA-15 materials were prepared via an equivalent-volume impregnation method. The resultant Fe 2 O 3 -containing SBA-15 materials showed good performance in phenol methylation. Under the same conditions, the mesoporous catalyst with 5 wt.% Fe 2 O 3 showed the superior catalytic activity to that of pristine α -Fe 2 O 3 even at lower reaction temperature (320 °C vs. 350 °C). The elevated catalytic activity observed for the mesoporous catalyst could be due to high level dispersion of Fe 2 O 3 species in the mesoporous framework. Furthermore, the mesoporous catalyst possessed long lifetimes, which could be used continuously for 2000 h without significant loss of activity. [ABSTRACT FROM AUTHOR]

• Ultrathin metal-porphyrinic MOF nanosheets were prepared. • A substrate-specific strategy for CO 2 cycloaddition was developed. • Cyclic carbonates were obtained in 84-99% yields at ambient and solvent-free conditions. • Insights into Co-TCPP-based cooperative systems were provided. A series of ultrathin (∼1.11–4.80 nm) 2D porphyrinic MOF nanosheets are developed and novel synergistic systems are conveniently constructed for the facile formation of cyclic carbonates. Using n -Bu 4 NBr (TBAB) as a co-catalyst, ultrathin (ca. 2.58 nm) Co-TCPP exhibited high catalytic activity for the solvent-free conversion of styrene oxide to cyclic carbonate, affording 99% yield at ambient conditions (25 °C and 1 atm CO 2). A relatively low energy (19.6 kcal/mol) for the rate-determining step is required for Co-TCPP/TBAB nanosystem as calculated by DFT. Notably, utilizing amino acid ionic liquid (AAIL, [Bmim][Glu] or [Bmim][His]) as the modifier, a substrate-dependent protocol was proposed to fix CO 2 with terminal epoxides or cyclohexene oxide, giving cyclic carbonates in 84–99% yields under mild conditions (solvent-free, 80 °C and 1 atm CO 2). 13C NMR and UV-vis studies provided insights into the vital roles of AAIL during CO 2 capture via carbamate dianion and in situ fabrication of Co-TCPP-AAIL. Moreover, DFT calculations also confirmed the AAIL-regulated substrate-dependent transformation strategy. 2D Co-TCPP-based synergistic systems are developed for the highly efficient synthesis of cyclic carbonates at ambient condition. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of a mild and efficient activation protocol for the nitrous oxide (N 2 O)-based selective oxidation has very important academic and applied values in the harmless treatment and high value-added utilization of N 2 O. This paper discloses that decatungstate (DT) anion and especially its hybrids with metal ions (1%M-DTs) are active for the N 2 O-involved oxidative dehydrogenation (ODH) of cyclohexanol in MeCN under visible light illumination. The best 1%Cu-DT achieves ca. 46.3% cyclohexanone yield and its turnover frequency (TOF) is up to 6.56 h-1 at high substrate concentration (1 M). Also, 1%Cu-DT is efficient for the N 2 O-involved ODH reactions of aliphatic and especially aromatic primary/secondary alcohols. UV–vis spectra, the isotope tracing tests of H 2 18O and DFT calculations support that the double-reduced H 2 DT species in situ-generated during the photo- reaction may turn into its oxygen-vacant state through dehydration, which the latter plays a crucial role in the oxygen transfer from N 2 O to it. [Display omitted] • DT is active for ODH reaction of alcohols with N 2 O under visible light. • Doping metal ions significantly enhance photocatalytic performance of DT • Blue double-reduced H 2 DT is key species for activation and O-transfer of N 2 O. • Generation of H 2 DT mainly relies on second step ODH reactivity of alcohols. • A double effect process as harmless treatment and value-added utilization of N 2 O. [ABSTRACT FROM AUTHOR]

This paper first discloses that two heteroleptic 8-quinolinolato iron(III) complexes (Qa 1 Qb 2 Fe III , Qa 2 Qb 1 Fe III ) could be synthesized conveniently via the coordination of FeCl 2 ·6H 2 O with 2 equivalents of 5,7-dichloro-8-hydroxyquinoline (Qb) or 5-chloro-8-hydroxyquinoline (Qa) under N 2 and then 1 equivalent of Qa or Qb under air. In comparison with the two homoleptic counterparts (Qa 3 Fe III and Qb 3 Fe III ), the proposed heteroleptic Q 3 Fe III complexes possessed similar coordination features to the Qb 3 Fe III one but showed similar catalysis performances to the Qa 3 Fe III one in the oxygenation of cyclohexane to cyclohexanol and cyclohexanone by hydrogen peroxide (H 2 O 2 ) in acetonitrile. More importantly, both heteroleptic Q 3 Fe III complexes showed a better accelerating effect on this reaction and provided a slightly higher conversion than the Qa 3 Fe III and especially Qb 3 Fe III ones. Furthermore, this predominance in catalytic activity was more strikingly apparent upon both-catalyzed oxygenations of benzene, toluene, ethylbenzene or thioanisole by H 2 O 2 . This should be due to a structurally distorted effect of the heteroleptic Q 3 Fe III complexes that is induced by the different in ligand environment, as supported by DFT B3LYP/6-311G (d) calculation. Based the present reaction and UV–vis spectral characterization results, a free radical mechanism for the present catalysis system was proposed. [ABSTRACT FROM AUTHOR]

• A series of Cu 3 (BTC) 2 nanoMOFs were synthesized. • Cu 3 (BTC) 2 -LA/IL nanosystem rendered facile aerobic oxidations of olefins at 313 K and 1 atm O 2. • Novel Cu 3 (BTC) 2 /IL systems afforded tunable and up to 91% selectivity. • Insights into Cu 3 (BTC) 2 -LA/IL/O 2 protocol were provided. Novel synergistic systems based on Cu-1,3,5-benzenetricarboxylate and ionic liquid are developed for the convenient conversion of renewable olefins, isoeugenol and β-caryophyllene, under very mild conditions (i.e. 313 K and 1 atm O 2). Using acidic ionic liquid [C 4 mim][HSO 4 ] (5.0 mol%) as co-catalyst, Cu 3 (BTC) 2 -Lauric acid (LA) afforded high selectivity (95.8%) and excellent yield (86.3%) for vanillin methyl ketone during the aerobic oxidation of isoeugenol. In comparison, 91.1% selectivity for vanillin together with 28.9% conversion of isoeugenol was obtained over Cu 3 (BTC) 2 -LA in the presence of amino acid ionic liquid, [C 4 mim][Ala]. Additionally, 91.3% selectivity and 86.5% yield for β-caryophyllene epoxide were provided by Cu 3 (BTC) 2 -LA with the aid of neutral [C 4 mim]Cl (5.0 mol%), indicating the importance of different types of ILs in tuning the microenvironments of designed Cu 3 (BTC) 2 -LA nanosystems. Simultaneously, Cu 3 (BTC) 2 -LA/IL showed superior stability during above-mentioned transformations, as verified by TEM, FT-IR and XRD analyses. Insights into the synergistic free radical routes were supported by fluorescence and DRUV-Vis characterizations. Cu 3 (BTC) 2 -LA/IL nanosystem was tunable for facile aerobic oxidations of renewable olefins at 313 K and ambient O 2 pressure. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper describes an electrochemical coupling epoxidation of cyclohexene by molecular oxygen (O) under mild reaction conditions. Herein, the electroreduction of O to hydrogen peroxide (HO) efficiently proceeds in a relatively environmentally friendly acetone/water medium containing electrolytes at 25-30 °C on a self-assembled H type of electrolysis cell with tree electrodes system, providing ca. 44.3 mM concentration of HO under the optimal electrolysis conditions. The epoxidation of cyclohexene with in situ generated HO simultaneously occurs upon catalysis by metal complexes, giving ca. 19.8 % of cyclohexene conversion with 78 % of epoxidative selectivity over the best catalyst 5-Cl-7-I-8-quinolinolato manganese(III) complex (QMn ( e)). The present electrochemical coupling epoxidation result is nearly equivalent to the epoxidation of cyclohexene with adscititious HO catalyzed by the QMn ( e). [ABSTRACT FROM AUTHOR]

The development of a simple and efficient process for the allylic oxidation of cyclic olefins with molecular oxygen can be one of the key technologies for synthesizing oxygenates. Here, we have developed a new protocol involving the “copper(II) chloride–acetylacetone” system for the aerobic oxidation of α-isophorone to keto-isophorone. Among the metal salts examined, CuCl was also found to be active to this allylic oxidation reaction in acetylacetone (acac). This is likely because the weak coordination of copper chloride with solvent acetylacetone molecules plays key roles in forming a catalytically active intermediate and realizing catalytic oxidation cycle, as supported by UV–vis spectrum, cyclic voltammetry measurements. The molecular structure of this intermediate was investigated theoretically by performing DFT/B3LYP calculations. The proposed Cu(acac)Cl 2 was optimized as keto-form and enol-form, and the enol-form with the higher reactivity was determined by the difference of LUMO and HOMO energies. The optimized geometries and calculated electronic spectra by TD-DFT were evaluated via comparison with experimental values, and a good agreement between calculated and experimental data was observed. Notably, this reaction was highly dependent on the water formed during the oxidation process, because H 2 O leads to the bad stability of the catalytically active intermediate, as supported by UV–vis spectra and cyclic voltammetry measurements. A high turnover frequency (TOF, 1.2 h −1 ) and an excellent yield for KIP product (64%) were achieved at ambient temperature (100 °C) under O 2 atmosphere. Based on these findings, a free radical mechanism for the present catalysis oxygenation system was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simultaneous steep increase of BET and construction of CN-based homojunction were achieved. • The CN-based homojunction photocatalytic CO 2 conversion performance was 13.8 or 16.1 times higher than that of pristine CN. • The adsorption and activation properties of catalysts for CO 2 were studied using the first principles calculations. • A detailed mechanism of photocatalytic CO 2 conversion was proposed based on in situ infrared characterization. The value-added conversion of CO 2 by photocatalytic reduction is considered as a potential way to solve the current energy and environmental crisis. In this paper, we report that a mechanical mixture of the as-thermally polymerized melamine (Me)- and 3-amino-1,2,4-triazole (AT)-based nitride carbons (MCN and TCN) can turn into a homojunction material (MTCN) by a calcination under air. A series of characterizations and photo-catalytic tests, combined with DFT calculations, support that the constructed MTCN has an improved porosity and photoelectric conversion efficiency. And the nitrogen-rich structure not only broadens the visible light response range but also provides stronger Lewis basic sites for the adsorption and activation of CO 2 at the surface. As a result, MTCN exhibits the most outstanding performance on tetracycline degradation under visible light illumination. In particular, its photo-catalytic efficiency for the visible-triggered CO 2 reduction under normal temperature and pressure can reach 7.75 μmol·g−1·h−1, which is 13.8 or 16.1 times higher than the single MCN or TCN. This work provides a facile pathway to construct CN-based homojunction photocatalyst for the efficient conversion of CO 2 into valuable products. [ABSTRACT FROM AUTHOR]

Decatungstate (DT) is very potential photo-catalyst for the dioxygens (O 2)-based selective oxidation but still needs to be improved in photo-catalytic efficiency and regeneration. This paper discloses that Au nanoparticles (NPs)-loaded DT (Au/DT) is conveniently synthesized via the reduction of chloroauric acids introduced in the synthesis of DT. A series of characterizations and quenching tests support that the doped Au NPs can remarkably improve the visible-light- harvesting and photo-excited quantum efficiencies of DT, and as the excellent electronic transport carriers, they also plays an additional role in converting O 2 into the active superoxide (•O 2 -) anion radical. As a result, the suggested Au/DT exhibits a significantly enhanced photo-catalytic efficiency for the visible-light-triggered selective oxidation of inert hydrocarbons under 25–28 °C and 1 atm pure O 2 atmosphere. Under optimized conditions, the best 1%Au/DT achieves 64.2% conversion and 93% acetophenone selectivity in the photo-oxidation of ethylbenzene and it has an outstanding regeneration ability. The hybridizing engineering (HE) strategy of Au NPs doping can improve DT's visible light harvesting efficiency and redox capacity via lowering frontier orbital energy levels, and in which Au NPs as the excellent electronic transport carriers also hoist DT's photo-excited quantum efficiency and the reactivity of O 2 in the visible light-driven selective oxidation of inert hydrocarbons. [Display omitted] • Firstly realizing the doping of Au NPs in the cage of non-lacunary decatungstate (DT). • Doped Au NPs remarkably improve DT's photo-physiochemical and redox properties. • Doped Au NPs play a crucial role in converting O 2 into active •O 2 - anion radical. • Au/DT possesses significantly enhanced visible-light-catalytic performance. • Au/DT has a good application potential in photo-catalytic oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

Abstract: Novel α-ketoesters were conveniently synthesized from acetylacetone and analogs via a vanadium-mediated one-pot tandem process. These advanced α-ketoesters could be selectively prepared under additive-free, mild conditions, viz., 1atm O2 pressure and 50–80°C. DFT calculations were performed to provide insights into the detailed mechanism of the tandem transformation. [Copyright &y& Elsevier]

Abstract: Periodic mesoporous organosilicas (PMOs), namely MCM-41, MSU, and SBA-15 ordered mesoporous silicas (OMSs) incorporated with bridging disulfide-ionic liquid moieties prepared either by the one-pot or the post-synthesis procedure, were used as supports for the gold nanoparticle (GNP) catalysts. The catalytic properties of various supported GNP/PMO catalysts were evaluated by epoxidation reaction of various olefins. It was found that the pore architectures of the PMO materials as well as the method by which organic moieties were incorporated onto the mesoporous silica materials play crucial roles in the particle size and dispersion of the GNPs which, in turn, dictate the catalytic performances of the supported GNP/PMO catalysts. In comparison with those synthesized by the one-pot procedure, PMO materials prepared by the post-synthesis method are more favorable in terms of dispersion of GNPs. Moreover, PMOs originated from OMSs with one-dimensional (1-D) pore structures also exhibit better GNP dispersions and catalytic activities than those with three-dimensional (3-D) pore architectures. This has been ascribed due to the restricted Ostwald ripening and/or migration-coalescence of the GNPs between adjacent pores of the PMOs with 1-D pore structures. [Copyright &y& Elsevier]

Abstract: A series of S-containing organic–inorganic hybrid mesoporous silicas were synthesized and used as supports for the fabrication of supported gold nanoparticle catalysts. It was found that the location and structure of organic moieties in these mesostructures played a crucial role in the dispersion level of gold nanoparticles, and thus, had a significant effect on the catalytic performance. Under optimum conditions, the gold nanoparticles supported on a periodic mesoporous organosilica with bridging disulfide-ionic liquid moieties showed excellent catalytic performance and reusability in epoxidation of styrene in the presence of H2O2-acetonitrile. Moreover, whole epoxidation process and role of gold nanoparticles were proposed. [Copyright &y& Elsevier]

Abstract: Selective oxidation of anethole with hydrogen peroxide to anisaldehyde has been developed using a novel efficient catalytic process by oxovanadium complexes bearing aromatic carboxylate ligands such as phthalate, salicylate and benzoate. Under mild reaction conditions (4h at 303K), oxovanadium(IV) phthalate complex (OPC)(IV) provided the best results with 100% conversion of anethole and 73.5% selectivity for anisaldehyde at low catalyst loading (∼0.5mol%). Inspiringly, H2O2 can be stoichiometrically used (H2O2:anethole=2:1) for the complete conversion. [Copyright &y& Elsevier]

Abstract: A novel solvent-regulated phase transfer catalyst of polymeric chiral salen Mn(III) complex with chiral diamine bridging was synthesized and its performance in the asymmetric epoxidation of styrene was investigated. In comparison with its low molecular weight counterpart of the homogeneous monomeric chiral salen Mn(III) complex, the polymeric chiral salen Mn(III) complex showed similar yield and enantioselectivity of the epoxide under the same reaction conditions. The effects of axial base, reaction temperature, and solvent on the catalytic performance of the polymeric chiral salen Mn(III) complex were investigated systematically. It was found that, under optimal reaction conditions, the yield of the epoxide and the enantioselectivity were as high as 98 and 47%, respectively. Furthermore, the polymeric chiral salen Mn(III) complex could be conveniently recovered for recycled use. Indeed the complex could be reused at least three times without significant losses of both activity and enantioselectivity. [Copyright &y& Elsevier]