A silica gel supported cobalt(Ⅱ) Schiff base complex as efficient and recyclable heterogeneous catalyst for the selective aerobic oxidation of alkyl aromatics

A silica gel supported cobalt（lI） Schiff base complex was synthesized and used for the oxidation of alkyl aromatics using molecular oxygen as an oxidant under atmosphere pressure. The catalyst shows a high conversion of alkyl aromatics and selectivity to benzylic ketones, and could be reused at least 5 times without significant loss of catalytic activity.

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices

In this study,graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe3O4@SiO2@GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons（PAHs） from water samples.The resulting microspheres（Fe3O4@SiO2@GO-PEA） were characterized by Fourier transform-infrared spectroscopy（FT-IR）,scanning electron microscopy（SEM）,CHNS elemental analysis,and vibrating sample magnetometry（VSM） techniques.The adsorbent possesses the magnetic properties of Fe3O4 nanoparticles that allow them easily to be separated by an external magnetic field.They also have the high specific surface area of graphene oxide which improves adsorption capacity.Desorption conditions,extraction time,amount of adsorbent,salt concentration,and pH were investigated and optimized.Following desorption,the PAHs were quantified by gas chromatography with flame ionization detection（GC-FID）.The limits of detection（at an S/N ratio of 3） were achieved from 0.005 to0.1 μg/L with regression coefficients（R2） higher than 0.9954.The relative standard deviations（RSDs） were below 5.8%（intraday） and 6.2%（inter-day）,respectively.The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7%and 106.7%（with RSDs of 1.6%to 8.4%,for n = 3）.The results indicated that the Fe3O4@SiO2@GO-PEA microspheres had a great promise to extraction of PAHs from different water samples.

Constructing a Z-scheme Fe-MOF-based heterostructure for visible-light-driven oxidation of aromatic alcohol in ambient air

Photocatalytic oxidation of aromatic alcohol into aromatic aldehyde using O_(2)has received huge atten-tion,while the reaction that occurred in ambient air is rarely studied but follows the green-chemistry principles.Herein,spindle-shaped MIL-53(Fe)-NH_(2)@ZnIn_(2)S_(4)photocatalysts with a Z-scheme heterostruc-ture were facilely developed for photocatalytic oxidation of aromatic alcohol in air under visible light.The benzyl alcohol conversion can be notably enhanced to 73%over the optimal MIL-53-NH_(2)@ZnIn_(2)S_(4)sample with a benzaldehyde production rate of 1825μmol g^(-1)h^(-1).However,in the O_(2)atmosphere,the benzyl alcohol conversion is only 56%,indicating that O_(2)is not required and has an adverse effect on the reaction.The hierarchical structure and Z-scheme heterojunction of MIL-53-NH_(2)@ZnIn_(2)S_(4)impart an efficient separation and strong redox abilities of photo-induced electrons and holes,which are respon-sible for the impressive photocatalytic performance.This study could motivate the ingenious design of Z-scheme heterostructures for green organic conversion based on MOFs.

Aromatic alcohols oxidation and hydrogen evolution over π-electron conjugated porous carbon nitride rods

Photocatalysis using polymeric carbon nitride(CN)materials is a constantly evolving field,where the variation of synthetic procedures allows the constant improvement of activity by tackling the intrinsic limitations of these materials(optical absorbance,specific surface area,charge migration,etc.).Amongst the possible photocatalytic reactions,the most popular application of CNs is the hydrogen evolution reaction(HER)from water.In this work,we design precisely-controlled carbon-doped porous CN rods with extended π-electron conjugation from supramolecular assemblies of melem and co-monomers,which partially substitute nitrogen for carbon atoms at the pyrimidine ring of the melem.Dense hydrogen bonds and good thermal stability of the melem-based supramolecular framework allow synthesizing a more ordered structure for improved charge migration;the control from the molecular level over the position of carbon-substituted nitrogen positions tailors the band alignment and photogenerated charge separation.The optimal photocatalyst shows an excellent HER rate(up to 10.16 mmol·h-1·g-1 under 100 W white light-emitting diode(LED)irradiation,with an apparent quantum efficiency of 20.0%at 405 nm,which is 23.2 times higher compared to a reference bulk CN).To fully harness the benefits of the developed metal-free CNs,selective oxidation reaction of aromatic alcohols is demonstrated with high conversion and selectivity.

Perfluoroalkylation of aromatic compounds with perfluoroalkyl radical generated from the oxidation of sodium perfluoroalkanesulfinate

Sodium perfluoroalkanesulfinates [R_fSO_2Na(1), Rf=CI(CF_2)_n; a, n=4; b, n=6; c, n=8] on oxidation with various single eletron oxidizing agents, such as Mn (OAc)_3·2H_2O and Ce (SO_4)_2, yielded perfluoroalkyl radicals capable of perfluoroalkylating aromatic compounds to give a mixture of o-and p-monoperfluoroalkylated products. Thus, this reaction provides a new method for the synthesis of o-and p-monoperfluoroalkyl substituted aromatic compounds.