Search

A mesoporous ZnIn2S4 photocatalyst shows notable activity for photoreforming of PLA, PET and PU to generate small organic chemicals and H2 fuel under simulated sunlight at room temperature.

Propylene molecule owns two active sites, the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of selectivity. In this work, the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin (MnTPPCl) was developed. The conversion of propylene was 12.7%, and the selectivity towards PO (propylene oxide) reached up to 80.5%. The formation of PO was attributed to the mechanism via high-valent Mn species, which was confirmed by means of in situ UV-vis spectrum.

The Friedel–Crafts alkylation strategy was used to prepare a hypercrosslinked polymer catalyst, which showed superior performance towards the cycloaddition reaction of CO2 with epoxides.

Under the background of carbon dioxide emission reduction, how to realize the treatment and the high value-added conversion of typical olefin volatile organic compounds (olefin-VOCs), such as styrene, is a big challenge. In this contribution, the ceria-supported coinage metal catalysts (M/CeO

Modeling and optimization is crucial to smart chemical process operations. However, a large number of nonlinearities must be considered in a typical chemical process according to complex unit operations, chemical reactions and separations. This leads to a great challenge of implementing mechanistic models into industrial-scale problems due to the resulting computational complexity. Thus, this paper presents an efficient hybrid framework of integrating machine learning and particle swarm optimization to overcome the aforementioned difficulties. An industrial propane dehydrogenation process was carried out to demonstrate the validity and efficiency of our method. Firstly, a data set was generated based on process mechanistic simulation validated by industrial data, which provides sufficient and reasonable samples for model training and testing. Secondly, four well-known machine learning methods, namely, K-nearest neighbors, decision tree, support vector machine, and artificial neural network, were compared and used to obtain the prediction models of the processes operation. All of these methods achieved highly accurate model by adjusting model parameters on the basis of high-coverage data and properly features. Finally, optimal process operations were obtained by using the particle swarm optimization approach.

Cation substitution in spinel cobaltites (e.g., ACo2O4, in which A = Mn, Fe, Co, Ni, Cu, or Zn) is a promising strategy to precisely modulate their electronic structure/properties and thus improve the corresponding electrochemical performance for water splitting. However, the fundamental principles and mechanisms are not fully understood. This research aims to systematically investigate the effects of cation substitution in spinel cobaltites derived from mixed-metal-organic frameworks on the oxygen evolution reaction (OER). Among the obtained ACo2O4 catalysts, FeCo2O4 showed excellent OER performance with a current density of 10 mA·cm−2 at an overpotential of 164 mV in alkaline media. Both theoretical calculations and experimental results demonstrate that the Fe substitution in the crystal lattice of ACo2O4 can significantly accelerate charge transfer, thereby achieving enhanced electrochemical properties. The crystal field of spinel ACo2O4, which determines the valence states of cations A, is identified as the key factor to dictate the OER performance of these spinel cobaltites.

The direct epoxidation of propylene to propylene oxide (PO) using molecular oxygen is difficult to achieve. Liquid-phase aerobic propylene epoxidation has been achieved using metalloporphyrin catal...

In this work, a mild and sustainable catalytic aerobic epoxidation of alkenes catalyzed by cobalt porphyrin was performed in the presence of sunflower seeds oil. Under ambient conditions, the conversion rate of trans-stilbene reached 99%, and selectivity toward epoxide formation was 88%. The kinetic studies showed that the aerobic epoxidation followed the Michaelis–Menten kinetics. Mass spectroscopy and in situ electron spin resonance indicated that linoleic acid was converted to fatty aldehydes via hydroperoxide intermediates. A plausible mechanism of epoxidation of alkenes was accordingly proposed.

The activation of dioxygen is the major challenge in the catalytic oxygenation of hydrocarbons under mild conditions. In this study, the catalytic efficiency for the aerobic oxidation of toluene and its derivatives by using cobalt meso-tetraphenylporphyrin was enhanced by using acetylacetone as the oxygen activator. The influences of reaction conditions such as solvent, different metalloporphyrin catalysts, temperature, pressure and acetylacetone loading were studied, as well as the kinetics of the oxidation. Various toluene derivatives could also be oxidized to the corresponding products in satisfactory yields with this catalytic system. Based on the characterization of in situ electron paramagnetic resonance (EPR) and in situ UV-vis spectroscopy, the catalytic mechanism was also proposed, in which acetylacetone served as the key initiator of the free radical in activating dioxygen.

A tubular MOF with adequate active sites is prepared by the bending of metal-coordinated honeycombed frameworks via titration and shows fast catalytic kinetics with lower catalytic loading for CO2 conversion. The TON is observed to be 2300 and the corresponding TOF of up to 173 h-1 is achieved for the first time.

Quaternary phosphine type hypercrosslinked polymer catalysts were successfully prepared using the Friedel-Crafts alkylation reactions, which benefit from the synergistic effects between the Brønsted acidity of the hydroxyl group and nucleophilicity of the Br

The oxidation of benzylic C H bonds by metalloporphyrins in supercritical carbon dioxide (scCO2) has still limited. Herein, an efficient protocol of aerobic oxidation of primary benzylic C H bond by cobalt porphyrin and NHPI (N-hydroxyphthalimide) in scCO2 was established. Using toluene as model substrate, 21.6% conversion and 81.2% benzoic acid selectivity was obtained under the optimized conditions. The protocol also exhibited good tolerance towards the oxidation of various substrates with different electron property groups. Moreover, a plausible mechanism involving free radical and high-valence cobalt species was proposed.

Graphical abstract The integrin αvβ3 receptor and Lactoferrin receptor (LfR) are over-expressed in both cerebral microvascular endothelial cells and glioma cells. RGD tripeptide and Lf can specifically bind with integrin αvβ3 receptor and LfR, respectively. In our study, RGD and Lf dual-modified liposomes loaded with docetaxel (DTX) were designed to enhance the brain targeting effect and treatment of glioma. Our in vitro studies have shown that RGD-Lf-LP can significantly enhance the cellular uptake of U87 MG cells and human cerebral microvascular endothelial cells (hCMEC/D3) when compared to RGD modified liposomes (RGD-LP) and Lf modified liposomes (Lf-LP). Free RGD and Lf competitively reduced the cellular uptake of RGD-Lf-LP, in particular, free RGD played a main inhibitory effect on cellular uptake of RGD-Lf-LP in U87 MG cells, yet free Lf played a main inhibitory effect on cellular uptake of RGD-Lf-LP in hCMEC/D3 cells. RGD-Lf-LP can also significantly increase penetration of U87 MG tumor spheroids, and RGD modification plays a dominating role on promoting the penetration of U87 MG tumor spheroids. The results of in vitro BBB model were shown that RGD-Lf-LP-C6 obviously increased the transport of hCMEC/D3 cell monolayers, and Lf modification plays a dominating role on increasing the transport of hCMEC/D3 cell monolayers. In vivo imaging proved that RGD-Lf-LP shows stronger targeting effects for brain orthotopic gliomas than that of RGD-LP and Lf-LP. The result of tissue distribution confirmed that RGD-LF-LP-DTX could significantly increase brain targeting after intravenous injection. Furthermore, RGD-LF-LP-DTX (a dose of 5 mg kg−1 DTX) could significantly prolong the survival time of orthotopic glioma-bearing mice. In summary, RGD and LF dual modification are good combination for brain targeting delivery, RGD-Lf-LP-DTX could enhance brain targeting effects, and is thus a promising chemotherapeutic drug delivery system for treatment of glioma. Supplementary Information The online version contains supplementary material available at 10.1186/s12951-021-01180-0.

Ionic liquid (IL)-modified metal/ZSM-5 composites served as heterogeneous catalysts toward cyclohexane aerobic oxidation, demonstrating excellent KA oil (cyclohexanol and cyclohexanone) selectivity with improved activity. The effects of the different functional groups of the IL on the oxidation were further systematically investigated. The catalytic activity of the catalyst was closely related to the anionic group of the IL, whereas the cationic group had no obvious effects. The cyclohexane conversion and selectivity of KA oil reached 9.7 and 92.2%, respectively, using the optimized catalyst C6mimHSO4-Co/ZSM-5. This favorable catalytic performance was mainly attributed to the activation of the cyclohexane by the anionic group of the IL, whereas the excellent selectivity was ascribed to the superior solubility of KA oil in the IL while avoiding overoxidation. Based on the results of in situ electron paramagnetic resonance spectra, a catalytic mechanism involving a free-radical process was also proposed.

The industrial oxidation of cyclohexane is currently performed with very low conversion level, i.e. 4-6% conversion and poor selectivity for cyclohexanone and cyclohexanol (K-A oil), i.e.70-85%, at above 150oC reaction temperature and above 10atm reaction pressure using molecular oxygen oxidant and homogeneous catalyst. Several disadvantages are, however, associated with the process, such as, complex catalyst-product separation, high power input, and low safe operation. Therefore, the oxidation of cyclohexane using heterogeneous catalyst oxygen oxidant from air at mild conditions has received particular attention. Aerobic oxidation of cyclohexane over ionic liquids modified cobalt/ZSM-5 (IL-Co/ZSM-5) in absence of solvents was developed in this article. The prepared catalysts were characterized by XRD, FT-IR, N2 adsorption-desorption, SEM, TEM and XPS analyses. The influence of reaction parameters on the oxidation of cyclohexane was researched, such as the various catalysts, reaction temperature, reaction time, and the reaction pressure, on the process. Highly selective synthesis of KA oil was performed by aerobic oxidation of cyclohexane using ionic liquids modified cobalt/ZSM-5 (IL-Co/ZSM-5) as the catalyst in absence of solvents for the first time. A selectivity of up to 93.6% of KA oil with 9.2% conversion of cyclohexane was produced at 150℃ and 1.5 MPa after 3 h, with about 0.1 mol cyclohexane, C7mimHSO4-Co/ZSM-5 catalyst equal to 6.0 wt%, respectively. The induction period of oxidation was greatly shortened when the ionic liquid was supported on ZSM-5. The catalyst was easy to centrifuge and was reused after five cycles. It was found that both the characterization and performance of the catalysts revealed that both the presence of oxygen vacancies with incorporation of Co ions into the framework of ZSM-5 and the introduction of C7mimHSO4 into the ZSM-5 leads to the both satisfactory selectivity and robust stability of the C7mimHSO4-Co/ZSM-5 heterogeneous catalyst.

In this study, convenient and selective oxidation of alcohols using aqueous hydrogen peroxide to yield carbonyl compounds was studied. Using the ruthenium-(4-methylphenyl-2,6-bispydinyl) pyridinedicarboxylate complex [Ru(mpbp)(pydic)] as a catalyst, primary and secondary alcohols were oxidized to aldehydes and ketones at room temperature with a satisfactory yield and excellent selectivity. The influence of various reaction parameters, such as solvent, catalyst and oxidant amount on both the activity and selectivity was also evaluated. Kinetic studies showed that the oxidation of alcohol was first order in terms of the substrate and hydrogen peroxide, and was second order in terms of the catalyst. A plausible mechanism involving ruthenium–oxo species with electrophilic character was proposed based on the in situ UV-vis spectroscopy studies and Hammett plots.

As stiff polymers are difficult to self-heal, the balance between polymers’ self-healing ability and mechanical properties is always a big challenge. Herein, we have developed a novel healable stiff polymer based on the Si-OR and Si-OSi dynamic covalent bonds. The self-healing mechanism was tested and proved by the small molecule model experiments and the contrast experiments of polymers. This polymer possesses excellent tensile, bending properties as well as room temperature self-healing abilities. Moreover, due to the sticky and shapeable properties under wetting conditions, the polymer could be used as an adhesive. Besides, even after four cycles of recycling, the polymer maintains its original properties, which meets the requirements of recyclable materials. It was demonstrated that the polymer exhibits potential application in some fields, such as recyclable materials and healable adhesives.

We report an efficient, reusable, and selective 6-aminothiouracil (ATA)-modified Zr(IV)-based adsorbent (defined as UiO-66-ATA(Zr)) for lead ion removal in water. The adsorption equilibrium time an...

In this paper, photocatalysts based on TiO2 nanotubes (TNTs) and TiO2 nanotube arrays (TNTAs) sensitized by Cu(II) meso-tetrakis(N-ethylpyridinium-4-yl) porphyrin (CuTEPyP) were synthesized and their structures were characterized by various analytical methods. The photocatalytic activities of both composites were then investigated through degradation of 4-nitrophenol (4-NP) in aqueous solutions under visible light irradiation. It was found that CuTEPyP/TNTAs could eliminate 95% 4-NP within 4 h, which was considerably higher than the yield obtained with CuTEPyP/TNTs (56%) under the same conditions. Compared to CuTEPyP/TNTs, the improved photocatalytic activity of CuTEPyP/TNTAs can be ascribed to increased light absorption, high separation rate of photo-generated charge pairs, and efficient charge transfer. A plausible photocatalytic degradation mechanism involving hydroxyl radicals, superoxide radical anions and singlet oxygen species was also proposed. This work presents an efficient paradigm for eliminating 4-NP under visible light irradiation.

Herein, CuO/Bi

Efficiency enhanced by cyclohexene: the efficiency towards diphenylmethane oxidation, catalyzed by metalloporphyrins, is improved remarkably in the presence of cyclohexene. As a NAD(P)H‐like model, the roles of cyclohexene, promoting the initiation of a radical and the activation of dioxygen, are demonstrated by a mechanistic study.

In this study, a novel system comprising metalloporphyrins and cyclohexene for the biomimetic aerobic oxidation of toluene and its derivatives was developed, which exhibited relatively benign reaction conditions, good catalytic activity, and broad substrate scope. Based on a series of in situ EPR (Electron Paramagnetic Resonance) and UV–vis experiments, the effect of cyclohexene on the reaction and the catalytic mechanism were preliminarily investigated.

An imidazolium-based ionic liquid (IL) functionalized zinc porphyrin catalyst was successfully synthesized for the first time, and was employed as an efficient catalyst for CO2 transformation including both the chemoselective synthesis of cyclic carbonates from various epoxides and the regioselective synthesis of 5-aryl-2-oxazolidinones from N-substituted aziridines. Detailed studies demonstrated that the intramolecular cooperative effect between the coordinated zinc center (electrophile) and flexible bromine anions (nucleophile) could mediate these reactions effectively under solvent-free and mild conditions. More importantly, the IL-based catalyst could be readily recovered by solvent precipitation and reused with retention of high activity and selectivity more than ten times based on the concept of “one-phase catalytic coupling with two-phase separation”.

On the basis of the development of function-oriented synthesis (FOS), we presented for the first time an efficient and one-pot construction of functional ionic polymers (FIPs) through the phenol–formaldehyde condensation process (pre-synthetic approach); FIPs had high density of Bronsted acidic and ionic sites. Considering the electrophilic–nucleophilic dual activation of phenolic hydroxyl groups and bromide anions, the imidazolium-based FIP-Im exhibited high activity for metal-, solvent- and additive-free synthesis of cyclic carbonates from CO2 and epoxides under mild conditions. Then, to obtain higher ionic density and a more flexible skeleton, FIP-Im@QA was also prepared by implanting quaternary ammonium (QA) in the framework of FIP-IMvia the Williamson ether synthesis (post-synthetic modification), which demonstrated high efficiency in the N-formylation reaction of multitudinous secondary amines with CO2 and PhSiH3 at ambient temperature. More interestingly, these function-oriented catalysts were compatible with the target transformation under low CO2 concentration (15% in 85% N2, v/v) and were also reused for more than six times without a significant loss of activity and selectivity. Therefore, this study could not only facilitate the design and construction of FIPs, but also provide sustainable protocols for efficient production of value-added chemicals from CO2 under mild conditions.

The highly efficient selective aerobic oxidation of benzyl alcohol to benzaldehyde catalyzed by cobalt porphyrin was achieved in a membrane microchannel reactor. The efficiency of benzyl alcohol oxidation was remarkably improved in the micro-structured chemical system, achieving a conversion and benzaldehyde selectivity of 82% and 98%, respectively, in 6.5 min. The classification and transfer of free radicals, as well as the oxygen-transfer mechanism, were determined by in situ EPR (electron paramagnetic resonance) and in situ UV–visible spectroscopy. Further kinetic studies revealed that the oxidation of benzyl alcohol follows the Michaelis–Menten kinetics, with Km = 0.133 mol/L.A mathematic kinetic model was proposed, and the kinetic model fitted the experimental data well. The mathematical model can predict the reaction process at a wide range of benzyl alcohol concentrations, which is beneficial for the process optimization and reactor design.

Efficient separation of propylene/propane (C3H6/C3H8) is an imperative and extremely challenging process in the petrochemical industry due to their similar physicochemical characters. Known tactics mainly concentrate on unilateral thermodynamic or kinetic driven. Here, we report the efficient separation of C3H6/C3H8 through cooperative equilibrium-kinetic synergetic effect in a nodes-engineered Zr-MOF scaffold (1to). The grafted -CF3 motif with different isomers and resultant aperture chemistry awards 1to a late-model paradigm for efficient separation of C3H6/C3H8. Detailly, confined -CF3 group having the role of H-bonding acceptor can result in improved adsorption enthalpy (Qst) of 38.1 kJ mol−1, ideal adsorbed solution theory (IAST) selectivity of 80 and experimental selectivity of 25, respectively, indicating a marked thermodynamic driven for trapping C3H6. Besides, the contracted cross-sectional size and eligible pore shape of 1to could be judiciously adjusted through rationally engineering the pore microenvironment, yielding a topmost simulated diffusion selectivity of 408, which was 40.8 times higher than that of the pristine 1 example (10), effectively enabling the swift diffusion behavior of C3H6. Modeling simulations and breakthrough experiments confirmed the excellent C3H6/C3H8 separation performance of 1to. This work successfully developed a novel nodes-engineered strategy for C3H6 capture through equilibrium-kinetic synergetic effect, anticipating to set a new benchmark for gas separation and affording constructive guidance for tailoring delicate aperture chemistry.

Removal of Pb(II) from water is an important issue for improving water quality. However, the use of cost-effective and more environmentally friendly adsorbents to achieve highly-efficient adsorption capacity is still a challenge. A novel bio-sorbent (PP-DBD) is developed by functionalizing pomelo peels to remove Pb(II) in water. PP-DBD achieves the enrichment of Pb(II) (adsorption amount of 443.51 mg/g and removal rate of 99.98%) after 2 h and exhibits good selectivity and reusability (6 cycles). Isothermal studies show that adsorption is an irreversible process with positive synergism of multiple sites, and a active site has the ability to adsorb 1.29 Pb(II). The kinetics indicates that adsorption is chemisorption and the rate-limiting step is surface diffusion. The thermodynamic study reveals that the adsorption of Pb(II) is enhanced at higher temperatures by a spontaneous process. This study also shows that hydroxyl sites have a better affinity and easier charge transfer capacity to Pb(II) than amino sites on PP-DBD by DFT and FMOs calculations. In conclusion, PP-DBD is a promising adsorbent for the removal of Pb(II) in aqueous solution.

Multifunctionalization of organic polymers for acting synergistically on substrate is of wide interest in the field of modern catalysis, but it is still a significant challenge. Herein, two novel bifunctional polymers were first designed and synthesized by combining ionic liquids (ILs) with zinc(II) porphyrin through simple and reversible Schiff base reactions. The fabricated polymers with flexible structures and nitrogen-rich environments presented high affinity toward CO2 molecules at ambient conditions. Owing to the cooperative nature of intercalated ILs and Lewis acidic metal sites, these materials could serve as efficient heterogeneous catalysts for the insertion of CO2 into epoxides to produce cyclic carbonates. As expected, these polymers exhibited good catalytic performance, robust constancy, excellent recyclability, and good substrate expansibility for this reaction in the absence of cocatalyst under mild or even ambient conditions. Notably, the selected catalyst SYSU-Zn@IL2 could directly conver...

Selective aerobic oxidation of hydrocarbons by molecular oxygen to afford valuable oxygen-containing functional compounds is a key challenge in modern chemical industry. Herein, an efficient catalytic system including metalloporphyrins as ideal catalysts and cumene as a co-substrate was developed for the aerobic oxidation of hydrocarbons to afford products with high yields and excellent chemoselectivities. Notably, this biomimetic process was found to be similar to cytochrome P450 monooxygenase-catalyzed reactions according to Michaelis–Menten kinetics. Experimental results and in situ monitoring techniques including the kinetic study, in situ ultraviolet–visible spectroscopy, and in situ electron spin resonance spectroscopy indicated that in situ generated cumyl hydroperoxide acted as an actual oxidant. Its formation was possibly mediated by metalloporphyrins to generate numerous free-radical species, and the high-valent Mn IV –oxo π-cation radicals were regarded as active species in the aerobic oxidation. Consequently, both the co-substrate specificity and the possible reaction mechanism were systematically investigated based on the control experiments and results obtained from our previous studies.

Multi-walled carbon nanotubes (MWCNTs) as metal-free catalysts presented excellent activity and selectivity in the Baeyer-Villiger oxidation of ketones to corresponding lactones in the presence of molecular oxygen and benzaldehyde. Different factors including catalyst, solvents, amount of catalyst were systematically investigated. Compared with MWCNTs, carboxylic multi-walled carbon nanotubes (c-MWCNTs) catalyst exhibited higher performance for the oxidation of ketones, showing good recyclability and reusability. The yield of e-caprolactone was obtained with 94% under the optimum conditions. Also, c-MWCNTs presented excellent activity towards the oxidation of various cyclic ketones to the corresponding lactones. The introduced carboxyl group on the surface of MWCNTs was favorable to obtain high dispersion in the reaction solution. In addition, the recording of in situ Electron Paramagnetic Resonance (EPR) and Raman spectroscopy indicated that carboxyl group could significantly stabilize the radical species in the reaction.

The combination of a zinc phthalocyanine (ZnPc) catalyst and a stoichiometric amount of dimethyl formamide (DMF) provided a simple route to formamide derivatives from amines, CO 2 , and hydrosilanes under mild conditions. We deduced that formation of an active zinc-hydrogen (Zn-H) species promoted hydride transfer from the hydrosilane to CO 2 . The cooperative activation of the Lewis acidic ZnPc by strongly polar DMF, led to formation of activated amines and hydrosilanes, which promoted the chemical reduction of CO 2 . Consequently, the binary ZnPc/DMF catalytic system showed excellent yields and superior chemoselectivity, representing a simple and sustainable pathway for the reductive transformation of CO 2 into valuable chemicals as an alternative to conventional halogen-containing process.

A facile and one-pot synthesis of metalloporphyrin-based ionic porous organic polymers (M-iPOPs) was performed through a typical Yamamoto-Ullmann coupling reaction for the first time. We used various characterization techniques to demonstrate that these strongly polar Al-based materials (Al-iPOP) possessed a relatively uniform microporosity, good swellable features, and a good CO2 capture capacity. If we consider the particular physicochemical properties, heterogeneous Al-iPOP, which bears both a metal active center and halogen anion, acted as a bifunctional catalyst for the solvent- and additive-free synthesis of cyclic carbonates from various epoxides and CO2 with an excellent activity and good recyclability under mild conditions. Interestingly, these CO2 -philic materials could catalyze the cycloaddition reaction smoothly by using simulated flue gas (15 % CO2 in N2 , v/v) as a raw material, which indicates that a stable local microenvironment and polymer swellability might promote the transformation. Thus, the introduction of polar ionic liquid units into metalloporphyrin-based porous materials is regarded as a promising new strategy for the chemical conversion of CO2 .

BACKGROUND Various proteins or enzymes were employed as organic components to form hybrid flowers, and they exhibited excellent properties in catalysis, adsorption, and sensing. However, there is no previous report of metalloporphyrins-based hybrid flowers. Based on the importance of metalloporphyrins in catalytic reactions, metalloporphyrins–copper phosphate hybrid flowers were prepared and their catalytic performance in epoxidation reactions was evaluated. RESULTS The composition, morphology, and crystallite structure of the hybrid flowers strongly depended on the incubation time (0.1–72 h) and concentration of metalloporphyrins in the mother liquor (0–47 µg mL−1). In comparison with the free metalloporphyrins, the hybrid flowers exhibited enhanced stability without any decrease in the catalytic activity. Moreover, the activity was linearly correlated with the surface content of metalloporphyrins which indicated that the metalloporphyrins on the surface were the key active species. Furthermore, the hybrid flowers showed good compatibility with a wide range of solvents and substrates. CONCLUSION The mechanism of formation of the hybrid flowers was proposed that involves four major successive steps: coordination, nucleation, formation, and growth. The catalytic results suggest that well-designed hybrid materials with hierarchical nano-structures and metalloporphyrins as organic component would be potential candidates for industrial catalysis applications. © 2017 Society of Chemical Industry

The chemical transformation of CO2 under mild conditions remains a great challenge because of its exceptional kinetic and thermodynamic stability. Two important reactions in the transformation of CO2 are the N-formylation reaction of amines using hydrosilanes and CO2, and the cycloaddition of CO2 to epoxides. Here, we report the high efficiency of bifunctional metallosalen complexes bearing quaternary phosphonium salts in catalyzing both of these reactions under solvent-free, mild conditions without the need for co-catalysts. The catalysts' bifunctionality is attributed to an intramolecular cooperative process between the metal center and the halogen anion. Depending on the reaction, this activates CO2 by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond (M–H) or the dual activation of epoxide via metal–oxygen coordinative bond (M–O). The one-component catalysts are also shown to be easily recovered and reused five times without significant loss of activity or selectivity. The current results are combined with previous work in the area to propose the relevant reaction mechanisms.

Cytochrome P450 enzyme-copper phosphate hybrid materials with flower-like shape were prepared with a simple but efficient coprecipitation method. The growth process of the hybrid flowers can be divided into three successive steps: coordination/nucleation, growth, and further ripen. The concentration of enzymes in the mother liquor exerted great influence on the morphology and surface enzyme content of the nano-composites. The catalytic performance in the reaction of selective oxidation of sulfide to sulfoxide was also investigated. The hybrid flowers exhibited superior catalytic performance: satisfied thioanisole conversion and selectivity to methyl phenyl sulfoxide (both above 97%) with H2O2 as oxidant under mild reaction conditions, excellent stability and recyclability, and wide scope of substrates. Such results indicate that the hybrid materials are potentially good candidates in the industrial enzyme catalysis.

A variety of unique Al(salen) complexes functionalized by imidazolium-based ionic liquid (IL) moieties with the salen ligand at the two sides of 3,3′-position have been successfully prepared, rather than familiar 5,5′-position reported previously. The catalytic activity obtained by these bifunctional catalysts could be superior to those of the binary type catalysts in the formation of five-membered heterocyclic compounds from the cycloaddition reaction of CO2 and three-membered heterocyclic compounds (including terminal epoxides and N -substituted aziridines), presumably due to the distinguished intramolecularly synergistic catalysis, which might lead to perform the cycloaddition reaction at ambient conditions and retain excellent yield and unprecedented chemo- or regioselectivity. Moreover, the polyether-based trifunctional Al(salen) catalysts with the best catalytic performance could be regenerated and reused at least eight times without any obvious decreases in catalytic activity. Finally, the kinetic investigation suggested the structure of catalysts had important influences on the catalytic activity, thereby proposing the possible reaction mechanism.