Solvothermal synthesis of Co-substituted phosphomolybdate acid encapsulated in the UiO-66 framework for catalytic application in olefin epoxidation

Hybrid composites of phosphomolybdic acid@UiO-66(PMo12@UiO-66)and Co-substituted phosphomolybdic acid@UiO-66(PMo11Co@UiO-66)were synthesized using the direct solvothermal method.A variety of characterization results demonstrated that phosphomolybdic acid(PMo12)or Co-substituted phosphomolybdate acid(PMo11Co)clusters are uniformly dispersed in the cages of Zr-based metal-organic UiO-66 frameworks.The catalytic properties of these hybrid composites were investigated by applying the epoxidation of olefins with tert-butyl hydroperoxide as the oxidant.Compared to PMo12@UiO-66,PMo11Co@UiO-66 showed a much higher catalytic activity and was simply recovered by filtration and reused for at least ten runs without significant loss of catalytic activity.Particularly,PMo11Co@UiO-66 can efficiently convert cyclic olefins like limonenes to epoxides,and its selectivity to 1,2-limonene oxide reached 91%in the presence of a radical inhibitor such as hydroquinone.The excellent catalytic activity and stability of the hybrid composite PMo11Co@UiO-66 are mainly attributed to the uniform distribution of highly active PMo11Co units within the smaller cages of UiO-66,to the suitable surface polarity of the hybrid composite for facilitating the access of reagents and solvent,and to the strong interface-interactions between the polyoxometalate and the UiO-66 framework.

Interfacial-interaction-induced fabrication of biomass-derived porous carbon with enhanced intrinsic active sites

Carbon catalysis is an attractive metal-free catalytic transformation,and its performance is significantly dependent on the number of accessible active sites.However,owing to the inherent stability of the C-C linkage,only limited active sites at the edge defects of the basal plane can be obtained even after a harsh oxidation treatment.In this study,the concept of interfacial interactions was adopted to propose an efficient strategy to develop highly active carbon catalysts.The alumina/carbon interface formed in situ acted as a cradle for the generation of oxygen-containing functional groups.In the absence of oxidation treatment,the concentration of oxygen-containing functional groups and the specific surface area can reach 1.27 mmol·g^(-1) and 2340 m^(2)·g^(-1),respectively,which are significantly higher than those of carbon prepared by traditional hard template methods.This active carbon shows a significant enhancement in catalytic performance in the oxidative coupling of amine to imine,about 22-fold higher than that of a well-known graphite oxide catalyst.Such interfacial interaction strategies are based on sustainable carbon sources and can effectively tune the porous structure of carbon in the micro-and meso-ranges.This conceptual finding offers new opportunities for the development of high-performance carbon-based metal-free catalysts.

Aerobic oxidative coupling of alcohols and amines to imines over iron catalysts supported on mesoporous carbon

Direct oxidative coupling of an alcohol and amine,with air or molecular oxygen as the oxygen source,is an environmentally friendly method for imine synthesis.We developed an Fe catalyst supported on mesoporous carbon（denoted by FeOx/HCMK-3） for this reaction with excellent activity and recyclability.FeOx/HCMK-3 was prepared by impregnating HNO3-treated mesoporous carbon（CMK-3） with iron nitrate solution.The highly dispersed FeOx species give FeOx/HCMK-3 high reducibility and are responsible for the high catalytic performance.Imine synthesis over FeOx/HCMK-3 follows a redox mechanism.The oxygen species in FeOx/HCMK-3 participate in the reaction and are then regenerated by oxidation with molecular O2.The reaction involves two consecutive steps：oxidative dehydrogenation of an alcohol to an aldehyde and coupling of the aldehyde with an amine to give an imine.Oxidative dehydrogenation of the alcohol is the rate-determining step in the reaction.

A multifunctional neuromodulation platform utilizing Schwann cell-derived exosomes orchestrates bone microenvironment via immunomodulation, angiogenesis and osteogenesis

Recent evidence highlights multifaceted biological needs to recapitulate the bone microenvironment for bone regeneration.Neurotization has great potential for realizing multi-system modulations in bone tissue engineering(BTE).However,a neural strategy involving all the key bone repair steps temporally has not yet been reported.In this study,we reported the neural tissue engineering hydrogel-encapsulated Schwann cell-derived exosomes(SC Exo).This sustained-release SC Exo system prominently enhanced bone regeneration by promoting innervation,immunoregulation,vascularization,and osteogenesis in vivo.Moreover,the in vitro results further confirmed that this system significantly induced M2 polarization of macrophages,tube formation of HUVECs,and BMSCs osteogenic differentiation.Furthermore,BMSCs osteogenesis was promoted by upregulating the TGF-β1/SMAD2/3 signaling pathway.In summary,a novel cell-free and easily prepared SC Exo neural engineering was successfully developed to promote bone regeneration by orchestrating the entire bone healing microenvironment,which may provide a new strategy for tissue engineering and clinical treatment of bone defects.