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Per- and polyfluoroalkyl substances (PFAS) reduction via the hydrated electron yields highly fluorinated (and thus still concerning) transformation products, which can be characterized via nontarget analysis using high-resolution mass spectrometry.

The liquid-phase reduction method with NaBH4 as the reductant is the most widely used method for sulfidized nanoscale zero-valent iron (SNZVI) synthesis. However, it is unclear how the reductant amount (e.g., NaBH4/Fe ratio) affects the physicochemical properties (i.e. Fe0 and S content, surface S speciation, and lattice constant of the Fe BCC structure) and reactivity of SNZVI. Herein, we synthesized SNZVI with different NaBH4/Fe ratios to assess how the NaBH4/Fe ratio affects their properties, and how these properties correlated to the reactivity and selectivity. The S/Fe molar ratio in the particles of SNZVI decreased from 0.15 to 0.02 when the NaBH4/Fe ratio increased from 1.5 to 5, respectively; meanwhile, the yield of SNZVI increased from 20% to 97%. The Fe0 content and the surface S2−/S22− molar ratio ([S2−/S22−]surface) increased with the increase of the NaBH4/Fe ratio, which enhanced the electron transfer of SNZVI. The trichloroethylene reactivity increased ∼8.5-fold when the [S2−/S22−]surface of SNZVI increased from 0.85 to 1.62, while the selectivity decreased from 82.8% to 64.4% accordingly, indicating that [S2−/S22−]surface could be an indicator for predicting the reactivity and selectivity of SNZVI. These results indicate that the NaBH4/Fe ratio is a possible reason for the lab-to-lab variability of SNZVI reactivity. A higher NaBH4/Fe ratio was favorable for the TCE dechlorination reaction while a lower NaBH4/Fe ratio could enhance the electron selectivity.

Electrocatalytic hydrodechlorination (ECH) has been proposed as a potential technology for the effective degradation of organochlorine contaminants. In this study, a nanoscale Pd/TiC catalyst with low resistance was dip-coated onto Ti, aiming to fabricate a stable Pd/TiC/Ti electrode with enhanced ECH reactivity for efficient dechlorination. Electrochemical techniques indicated that the Pd/TiC/Ti electrode had a larger electrochemically active surface area and more rapid interfacial charge transfer than the conventional Pd/C/Ti electrode. In a batch experiment, the dechlorination rate for ECH of 2,4-dichlorobenzoic acid (2,4-DCBA, a model pollutant) by Pd/TiC/Ti was 1.3–14.5 times higher than those by Pd/C/Ti, Pd/MWCNTs/Ti, and Pd/MoS2/Ti, respectively. Scavenger experiments, ESR spin-trapping spectroscopy, and cyclic voltammetry clarified the intensified atomic H* generation by Pd/TiC/Ti. DFT calculations revealed that Pd/TiC/Ti had stronger binding ability with atomic H* (Eads: −2.89 eV vs. −2.44 eV) and 2,4-DCBA (Eads: −3.62 eV vs. −2.15 eV), respectively, when compared with Pd/C/Ti. As a result, enhanced generation of atomic H*, together with strengthened adsorption of atomic H* and 2,4-DCBA, would contribute to a faster ECH reaction. The Pd/TiC/Ti electrode retained its reactivity after 10 successive batch experiments (80 h), and showed high tolerance to the constituents in actual water matrices including lake water and river water. This study proposed a promising ECH electrode for the treatment of chlorinated organics in water matrices.

The fast development of wearable and portable smart electronics has immensely encouraged the demand for miniaturized integrated electronic devices. In this study, we utilized a duplex printing strategy to construct an all-in-one integrated electronic device by integrating asymmetric micro-supercapacitors (MSCs) with a tandem line-type temperature sensor (TLTS) based on reduced graphene oxide (rGO). In the integrated configuration, the 3D printing asymmetric MSCs based on MXenes/single-walled carbon nanotubes (SWCNTs) positive electrode and rGO/SWCNTs negative electrode delivered a large areal specific capacitance of 30.76 mF cm−2, high energy density of 8.37 μW h cm−2, and long lifetime (no significant capacitance decay of over 10 000 cycles). Moreover, the assembled device can offer the stable out power to TLTSs. Particularly, the temperature sensitivity of the duplex printed integrated electronic device can reach 1.2% per degree celsius. Collectively, the efficient 3D printing strategy can be used to build diverse all-in-one integrated electronic devices with state-of-the-art performance for next-generation wearable and portable electronics.

We describe an eco-friendly, practical and operationally simple procedure for the bis(methoxypropyl) ether-promoted oxidation of aromatic alcohols into aromatic carboxylic acids and aromatic ketones with atmospheric dioxygen as the sole oxidant. This chemical process is clean with high conversion and good selectivity, and an external initiator, catalyst, additive and base are not required. The virtue of this reaction is highlighted by its easily available and economical raw materials and excellent functional group tolerance (acid-, base- and oxidant-labile groups).

By using water as the hydrogen source, an eco-friendly and practical protocol for the synthesis of Z-vinyl thiocyanates through ultrasound-promoted Bronsted acid ionic liquid-catalyzed hydrothiocyanation of activated alkynes under minimal solvent conditions has been developed. This process effectively avoids the use of organic solvents, metal catalysts and harsh reaction conditions. This reaction shows attractive characteristics such as operational simplicity, broad substrate scope with good to excellent yields, ease of scale-up and high energy efficiency and recyclable and reusable catalysts.

A simple and practical method for the synthesis of alkenyl dithiocyanates and alkenyl diselenocyanates has been developed via stereoselective difunctionalization of alkynes with NaSCN or KSeCN at room temperature. Through this methodology, a series of alkenyl dithiocyanates and alkenyl diselenocyanates could be efficiently and conveniently obtained in moderate to good yields under mild and metal-free conditions by the simple use of oxone and PhI(OAc)2 as the oxidants.

A convenient and efficient indium-catalyzed approach to synthesize alkenyl iodides has been developed through direct iodoalkylation of alkynes with alcohols and aqueous HI under mild conditions. This catalytic protocol offers an attractive approach for the synthesis of a diverse range of alkenyl iodides in good to excellent yields.

A simple and facile method is described for the morphology-controlled synthesis of bimetallic Au–Pd alloyed nanochain networks (NNCs) that show high catalytic performance for the Ullmann intermolecular homocoupling of aromatic or alkyl halides (X = I, Br, Cl) in aqueous media and can be reused at least five times, which can also be applied to intramolecular homocoupling.

A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1 : 1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C–Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.

A Ni-catalyzed oxidative C–H/C–H cross-dehydrogenative coupling (CDC) reaction was developed for constructing various highly functionalized alkyl (aryl)-substituted thiophenes. This method employs thiophenes and aliphatic (aromatic) amides that contain an 8-aminoquinoline as a removable directing group in the presence of a silver oxidant. The approach enables the facile one-step synthesis of substituted thiophenes with high functional group compatibility via double C–H bond cleavage without affecting C–Br and C–I bonds. DFT calculations verify the importance of KH2PO4 as an additive for promoting C–H bond cleavage and support the involvement of a Ni(III) species in the reaction.

Highly ordered three-dimensional (3D) polypyrrole (PPy) coated cobalt oxide (Co3O4) nanoneedle arrays (NAs) anchored on Cu foams (Co3O4 NAs@PPy) are fabricated for electrochemical sensors to detect trace lead ions (Pb2+).

Pd–Pt nanodendrites were synthesized by a facile, environment-friendly, one-pot wet-chemical method, without using any seed, template, or toxic organic solvent. The as-obtained bimetallic nanocrystals exhibited efficient catalytic activity toward ligand-free Suzuki cross-coupling reaction in ethanol aqueous solution. A series of biphenyl compounds were obtained with high yields under mild conditions. Furthermore, the catalyst could be easily recovered and reused at least 6 consecutive cycles, nearly without losing its catalytic activity.

A facile strategy is designed for the fabrication of hollow, Sn–Ni nanoparticles (NPs) surrounded by ion-conductive, polyethylene oxide (PEO) coating to address the structural and interfacial stability concerns facing Sn-based anodes. In the unique architecture of hollow Sn–Ni@PEO NPs, the ductile inactive Ni as a buffer matrix can alleviate the volume change of Sn. Moreover, the synergistic effect between the elastic ion-conductive PEO coating and the hollow interior forces the active Sn to expand inward into the hollow space in the lithiated state, and thus effectively accommodates the substantial volume expansion. In particular, the PEO coating not only suppresses the unfavorable aggregation and pulverization of Sn during cycling, but also helps in forming a stable solid electrolyte interface (SEI) film on the high surface area nanostructured electrodes. Benefiting from the structural features, hollow Sn–Ni@PEO NPs exhibit a reversible capacity of 584 mA h g−1 after 100 cycles with excellent coulomb efficiency of higher than 99%, superior to the bare counterparts. The contribution to the excellent cycling performance by the PEO coating and the hollow structure is verified by galvanostatic charge/discharge cycling, cyclic voltammetry, electrochemical impedance spectroscopy and SEM measurements.

Commercial copolymer Luviset clear (L1), an environmentally benign and efficient ligand, was used to facilitate the catalytic performance of Cu(NO3)2 for homo-coupling of terminal alkynes. A series of substituted aromatic and aliphatic terminal alkynes were investigated. It was found that Cu(NO3)2@L1 can catalyze the C–C coupling reactions without any other base, and the corresponding diynes are generated in good to excellent yield. X-ray photoelectron spectroscopy was used to study the reaction mechanism, and the results evidence a Cu(II)/Cu(I) catalytic system. Additionally, the catalyst can be easily separated and reused without showing significant loss of catalytic activity.

A facile and scalable synthesis approach is developed for fabrication of a three-dimensional (3D) polyaniline (PANi)/graphene oxide (GO) hybrid hydrogel evenly embed with hollow Sn–Cu nanoparticles (Sn–Cu NPs) as high performance anode for lithium-ion batteries. The hierarchical conductive hydrogel was prepared via in situ polymerization of aniline monomer on the surface of Sn–Cu NPs and GO nanosheets. The morphology and structure of the resulting hybrid materials have been characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hierarchical conductive hydrogel framework with dendritic PANi nanofibers and 2D GO nanosheets serve as a continuous 3D electron transport network and high porosity to accommodate the volume expansion of Sn–Cu NPs. The PANi coating plays an “artificial SEI” function to preserve the structural and interfacial stabilization of Sn–Cu NPs during the cycling processes. As a consequence of this 3D hybrid anode, an extremely long stable cycling performance is achieved with reversible discharge capacity over 693 mA h g−1 after 200 cycles at current rate of 0.2 C and a reversible capacity of 371 mA h g−1 retention at a much higher current rate of 2 C, suggesting that this novel Sn–Cu/PANi/GO composite is a promising candidate for energy storage applications.

A non-enzymatic electrode is proposed as a glucose sensor based on Pt-replaced Ni nanowires which are prepared by constant current electro-deposition within the anodic alumina membrane and galvanic replacement reaction. The amperometric detection of glucose shows a wide linear range up to 13.5 mM with a high sensitivity of 124.17 μA mM−1 cm−2 and a low detection limit of 32 μM (S/N = 3). More important, another attractive feature of the Pt–Ni NATs electrode is the quite low working potential at −0.35 V (versus SCE), which is favorable to avoid the influence of possible intermediates. Furthermore, the non-enzymatic glucose sensors reveal good stability and repeatability. All these excellent properties of the Pt–Ni NATs electrodes can be attributed to the large active area supported by the unique nanotube array structure.

The copper-mediated direct thiolation of carbazole derivatives with disulfides via C(sp2)–H bond cleavage was developed for synthesizing diaryl and alkyl aryl sulfides. This reaction exhibits wide tolerance toward various functional groups giving the products in good yields without any additives or ligands, and can be easily extended to the synthesis of thioethers carrying a benzo[h]quinolone, 2-phenylquinoline, or indole moiety in satisfactory yields.

Iron–manganese binary oxide (FeMnOx) is considered highly effective for arsenic adsorption, however, the agglomeration effect hindered its practical application. In this study, graphene has been used as a supporting matrix to disperse FeMnOx due to its huge specific surface area, and the synthesized novel composite adsorbent (FeMnOx/RGO) was employed for arsenic removal. Results demonstrated that FeMnOx/RGO (mass ratio of FeMnOx to FeMnOx/RGO nanocomposites is 45%) has larger specific surface area (411 m2 g−1) in comparison with bare FeMnOx, and showed 10.16 mg As g−1 FeMnOx and 11.49 mg As g−1 FeMnOx adsorption capacities for As(III) and As(V), respectively, with 1 mg L−1 initial concentration. Increased in the initial concentration to 7 mg L−1, the adsorption capacities of As(III) and As(V) reached to 47.05 mg As g−1 FeMnOx and 49.01 mg As g−1 FeMnOx, respectively. The removal process perfectly obeys pseudo second-order kinetic model for both As(III) and As(V). And PO43− was found to strongly inhibit arsenic adsorption. Furthermore, adsorption tests and characterization analyses confirmed that MnO2 played a key role on the oxidation of As(III), while iron(III) oxide was found crucial to As(V) removal. Electrostatic interaction and surface complexation mechanisms involved in the adsorption. These findings suggested that the adsorbent could be used in real arsenic-contaminated water treatment.

In trace amounts, selenium (Se) participates in different physiological functions of the human body. Its biological significance is manifested in its presence as selenocysteine (Sec) in genetically encoded selenoproteins that are important in redox regulation, anti-inflammation, and cancer treatment. Recently, stimuli-responsive micelles were developed as biosensors, but there are no nanomicelle probes for the selective imaging of Sec under biological conditions (pH = 7.4). Herein, we report the design and preparation of a 2,4-dinitrobenzenesulfonyl-decorated block poly(carbonate) copolymer, viz. PMPC-Dns, for Sec imaging. We found that PMPC-Dns trapped with the fluorescent drug doxorubicin (DOX) selectively responds to Sec, while getting little interference from biological thiols, amines or alcohols. We applied the PMPC-Dns probe successfully to image endogenous Sec in cervical cancer tissues as well as in HeLa cells. In the course of these studies, we observed simultaneous release of the trapped DOX. Hence, besides Sec imaging, the probe can be used for controlled delivery of hydrophobic molecules for biomedical applications.

Transition metals have attracted much attention due to their high energy density in lithium-ion batteries (LIBs). However, the huge volume change and the fast capacity fading still limit their application. If the microstructure of the electrode materials can be designed properly, the volume change problems encountered during lithiation and delithiation could be alleviated to some extent. Here, novel three-dimensional (3D) hybrid Sn–Co nanowire arrays coated by poly(methyl methacrylate) (Sn–Co@PMMA NWs) are synthesized via a simple electrodeposition method followed by in situ emulsion polymerization. The electrode structure is well preserved after repeated Li-ion insertion/extraction, indicating that the positive synergistic effect of the Sn–Co NWs and uniform PMMA layer could effectively accommodate the volume expansion of tin anode materials. The electrochemistry results demonstrate that the Sn–Co@PMMA NWs electrode exhibits a high reversible capacity, a high initial coulombic efficiency, a good rate capability, and an improved capacity retention compared with the bare Sn–Co NWs electrode. This proposed nanoengineering strategy is proven to be an ideal candidate for the development of high performance anode for LIBs.

Nanoreactors are material structures that provide engineered internal cavities that create unique confined nanoscale environments for chemical reactions. Crumpled graphene nanoparticles or "nanosacks" may serve as nanoreactors when filled with reactive or catalytic particles and engineered for a specific chemical function. This article explores the behavior of crumpled graphene nanoreactors containing nanoscale ZnO, Ag, Ni, Cu, Fe, or TiO2 particles, either alone or in combination, in a series of case studies designed to reveal their fundamental behaviors. The first case study shows that ZnO nanoparticles undergo rapid dissolution inside the nanoreactor cavity accompanied by diffusive release of soluble products to surrounding aqueous media through the irregular folded shell. This behavior demonstrates the open nature of the sack structure, which facilitates rapid small-molecule exchange between inside and outside that is a requirement for nanoreactor function. In a case study on copper and silver nanoparticles, encapsulation in graphene nanoreactors is shown in some cases to enhance their oxidation rate in aqueous media, which is attributed to electron transfer from the metal core to graphene that bypasses surface oxides and allows reduction of molecular oxygen on the high-area graphene shell. Nanoreactors also allow particle-particle electron transfer interactions that are mediated by the connecting conductive graphene, which give rise to novel behaviors such as galvanic protection of Ag nanoparticles in Ag/Ni-filled nanoreactors, and the photochemical control of Ag-ion release in Ag/TiO2-filled nanoreactors. It is also shown that internal graphene structures within the sacks provide pockets that reduce particle mobility and inhibit particle sintering during thermal treatment. Finally, these novel behaviors are used to suggest and demonstrate several potential applications for graphene nanoreactors in catalysts, controlled release, and environmental remediation.

Silica-coated magnetite (Fe3O4@SiO2) nanoparticles functionalized with amino, imino and sulfonic groups (Fe3O4@SiO2–mPD/SP) were successfully synthesized via a facile chemical oxidative polymerization of m-phenylenediamine (mPD) and m-sulfophenylenediamine-4-sulfonic acid (SP) monomers, and utilized for selective removal of Pb(II) and Cr(VI) from aqueous solutions. It was revealed by the characterizations that the polymers formed on Fe3O4@SiO2 nanoparticles were the true copolymers with a mPD–SP unit, rather than a mixture of mPD and SP homopolymers. Fe3O4@SiO2–mPD/SP nanocomposites could be easily separated from aqueous solutions within 30 s. The maximum adsorption capacities of Pb(II) (83.23 mg g−1) and Cr(VI) (119.06 mg g−1) on Fe3O4@SiO2–mPD/SP nanocomposites were obtained at the mPD/SP molar ratios of 95 : 5 and 50 : 50, respectively. Moreover, satisfactory selective removal of Pb(II) and Cr(VI) from their mixtures with Cu(II) and Ni(II) ions were exhibited by the Fe3O4@SiO2–mPD/SP (95 : 5) and Fe3O4@SiO2–mPD/SP (50 : 50), respectively. The Pb(II) adsorption equilibrium was reached within 5 min by Fe3O4@SiO2–mPD/SP (95 : 5). The adsorption data of Pb(II) and Cr(VI) were both fitted well to the Freundlich isotherm and followed the pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) and Cr(VI) on Fe3O4@SiO2–mPD/SP nanocomposites included five processes, namely: ion-exchange, complexation adsorption, reduction reaction, electrostatic attraction and physical adsorption. The enhanced adsorption performance of nanoparticle-based magnetic adsorbents for selective removal of heavy metal ions can be achieved with such a copolymerization strategy.

In order to optimize the electrode system of lithium-ion batteries for problems such as lithium ion diffusion, electron transportation, and large volume changes during cycling processes, a novel anode material composed of ultrafine Sn nanoparticles (∼5 nm) anchored inside a well-connected three-dimensional (3D) polypyrrole (PPy) nanosheet network has been designed and synthesized through a simple microemulsion-based preparation of tin nanoparticles with organic crystal surface-induced PPy polymerization. In this electrode material, the ultrathin PPy coating (∼3–4 nm) plays a “flexible confinement” function to preserve the structural and interfacial stabilization of inner Sn nanoparticles as well as a “binder” function to suppress the detachment of Sn from the collector. Meanwhile, the continuous conductive PPy nanosheet network with open structures and large contact surface for Sn nanoparticle dispersion can provide easy access for Li+ intercalation. As a result, the integration of a 3D conductive network and ultrafine Sn nanoparticles with an ultrathin in situ PPy coating induces improved structural integrity and accessible capacity for Sn nanoparticle electrodes. It delivered a high capacity retention of 766 mA h g−1 after 200 cycles at the current density of 0.2 A g−1 and a reversible capacity of 583 mA h g−1 when kept at a much higher current density of 2 A g−1.

A series of strong Lewis acid air-stable titanocene perfluoroalkyl(aryl)sulfonate complexes Cp2Ti(OH2)2(OSO2X)2·THF (X = C8F17, 1·THF; X = C4F9, 2·H2O·THF; X = C6F5, 3) were successfully synthesized by the treatment of Cp2TiCl2 with C8F17SO3Ag, C4F9SO3Ag and C6F5SO3Ag, respectively. In contrast to well-known titanocene bis(triflate), these complexes showed no change in open air over three months. TG-DSC analysis showed that 1·THF, 2·H2O·THF and 3 were thermally stable at 230 °C, 220 °C and 280 °C, respectively. Conductivity measurements showed that these complexes underwent ionic dissociation in CH3CN solution. X-ray analysis results confirmed that 2·H2O·THF and 3 were cationic. ESR spectra showed that the Lewis acidity of 1·THF (1.06 eV) was higher than that of Sc(3+) (1.00 eV) and Y(3+) (0.85 eV). UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2·H2O·THF. Fluorescence spectra showed that the Lewis acidity of 2 (λ(em) = 477 nm) was higher than that of Sc(3+) (λ(em) = 474 nm). These complexes showed high catalytic ability in various carbon-carbon bond forming reactions. Moreover, they show good reusability. Compared with 1·THF, 2·H2O·THF and 3 exhibit higher solubility and better catalytic activity, and will find broad applications in organic synthesis.

The utilization of organoantimony (bismuth) complexes in CO2 fixation is reviewed in this article. The efficient synthesis of cyclic carbonates from CO2 and epoxides over an organoantimony(V) catalyst was first reported in 1979. After that, several organoantimony(V) complexes were found to be active for CO2 fixation. In 2009, an organoantimony(III) complex was reported as an effective CO2 absorbent and it is the only example of this kind. The study of organobismuth complexes for CO2 fixation started in 2008, and the achievements are: (i) when organobismuth oxides, hydroxides and methoxides are used as CO2 absorbents, they are converted to carbonates, and the organobismuth carbonates can be renewed as organobismuth oxides; (ii) organobismuth complexes can be used as catalysts to transform CO2 into epoxides as cyclic carbonates at room temperature in the presence of a co-catalyst such as LiI and Bu4NI; (iii) there is the development of bimetallic organobismuth complexes that show cooperative catalytic action; (iv) there is the physical fixation of CO2 by inorganic–organic bismuth complexes; and (v) CO2 insertion into the Bi–C bond of an organobismuth complex is disclosed. Most of the above catalytic systems can be considered as “electrophile–nucleophile”. In general, the synthesis of cyclic carbonates from CO2 and epoxides catalyzed by an organoantimony (bismuth) complex follows the mechanism: the complex first reacts with CO2 to form an organometallic carbonate, then the carbonate reacts with an epoxide with ring-opening by a base (e.g., n-Bu4NI).

Highly ordered three-dimensional (3D) polypyrrole (PPy) coated cobalt oxide (Co3O4) nanoneedle arrays (NAs) anchored on Cu foams (Co3O4 NAs@PPy) are fabricated for electrochemical sensors to detect trace lead ions (Pb2+). The 3D hybrid Co3O4 NAs@PPy is synthesized via a hydrothermal method followed by a chemical vapor phase polymerization process. Free-standing Co3O4 NAs@PPy can be directly utilized as a 3D electrochemical working electrode without being decorated onto a working electrode like Au and glassy carbon electrodes. In the mean time, the simultaneous incorporation of PPy, Co3O4 and Cu foams creates a platform with significantly improved electrochemical properties and excellent sensitivity for a large specific surface area, eminent adsorption capacity and high conductivity. Square wave anodic stripping voltammetry (SWASV) is carried out to observe the electrochemical behavior of the Co3O4 NAs@PPy electrode. Under the optimum conditions, a linear range between the currents and the concentrations of Pb2+ from 0.024 to 0.48 μM with a high sensitivity of 85.5 μA μM−1 was obtained. The limit of detection can reach 0.58 nM. The results confirmed that the modified electrode is a good candidate for Pb2+ detection sensors with excellent reproducibility, stability and lower detection limit. In addition, the developed method was successfully applied to determine Pb2+ in real water samples with satisfactory results.

Organometallic Lewis acids play an important role in modern organic synthesis. How to design and synthesize highly efficient and recyclable organometallic Lewis acid catalysts that can be conveniently applied in chemical reactions are key issues for sustainable synthetic processes. In general, stronger acidity means higher catalytic activity for organometallic Lewis acids. However, with the rise in acidity, the compound becomes more susceptible to hydrolysis and cannot be recycled. Simultaneous improvement of the hygroscopic character and Lewis acidity/catalytic activity of organometallic Lewis acids is highly desirable from the standpoint of practical applications. In this mini-review, the history of air-stable organometallic Lewis acids is introduced, with emphasis on our research works on metallocene, organobismuth, and organoantimony Lewis acids to the aspects of synthesis, characterization and catalytic application in carbon–carbon bond (Friedel–Crafts acylation, Mukaiyama aldol reactions; allylation, cyclotrimerization, Mannich reactions, cross-condensation reactions) and carbon–heteroatom bond (acylation, S–S bond cleavage, glycosylation) formation reactions. In terms of stability, storage, versatile ability, high catalytic activity and chemo-/stereo-selectivity, the complexes will find broad applications in organic synthesis.

The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4 is highly efficient in the cross-condensation of aldehydes with ketones. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability.

An air-stable cationic organobismuth complex was successfully synthesized and found to show high catalytic efficiency in the direct diastereoselective Mannich reaction in water.