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Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels‐Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long‐established mechanistic picture of pericyclic rearrangements by demonstrating that seven‐membered borepins (i. e., heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels‐Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes., New insights into the reactivity of perarylated boroles toward alkynes have been derived from both experimental and computational studies. It is shown that borepins (the formal alkyne insertion products) can readily isomerize to the thermodynamically more favorable boranorbornadienes (the formal Diels‐Alder products), thus obscuring the mechanism of product formation (see Figure). In addition, the fluorescent nature of the tricyclic boracyclohexenes, the most stable isomers of the addition reactions, has been investigated by absorption and emission spectroscopy.

Owing to an empty p orbital and a lone pair of electrons on the Si center, silylene exhibits reactivity similar to a transition-metal system capable of activating H2/C-H bonds and small molecules. In this work, with the aid of density functional theory calculations, we systematically investigated the reactions of an acyclic silylene with CO, CO2, and N2O. The detailed mechanisms obtained lead to an in-depth understanding of the silylene single-site ambiphilic reactivity.

Transition metal–boryl complexes play an important role as reactive intermediates in catalytic borylation processes and have enjoyed tremendous exploration. Over the years, it has been well establi...

Biomimetic modularization and function-oriented synthesis of structurally diversified natural product-like macrocycles in a step-economical fashion is highly desirable. Inspired by marine furanocembranoids, herein, we synthesize diverse alkenes substituted furan-embedded macrolactams via a modular biomimetic assembly strategy. The success of this assembly is the development of crucial Pd-catalyzed carbene coupling between ene-yne-ketones as donor/donor carbene precursors and unactivated Csp3‒H bonds which represents a great challenge in organic synthesis. Notably, this method not only obviates the use of unstable, explosive, and toxic diazo compounds, but also can be amenable to allenyl ketones carbene precursors. DFT calculations demonstrate that a formal 1,4-Pd shift could be involved in the mechanism. Moreover, the collected furanocembranoids-like macrolactams show significant anti-inflammatory activities against TNF-α, IL-6, and IL-1β and the cytotoxicity is comparable to Dexamethasone.

The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.

[(η6-p-cymene)OsI2]2 was found to be a good catalyst for the cyclopropanation reaction of isobutyl vinyl ether with 3-tert-butyldiazoindene. In contrast, the complexes [(η6-p-cymene)OsX2]2 (X = Cl,...

Highly-efficient and eco-friendly materials and technologies are urgently needed to meet the requirements of nowadays green development. Photocatalysis with using solar energy and enzymatic catalysis with eco-friendly nature are effective alternatives to address the problem. Notably, beneficial use of the synergistic effect of artificial enzyme and advanced photocatalyst has attracted wide attention. This work presents a biomimetic photocatalytic material, two-dimensional (2D) biomimetic hemin-bismuth tungstate (HBWO). Stable HBWO composites formed by immobilization of monomeric hemin on 2D bismuth tungstate layer, exhibit high photocatalytic performance, better than that of pure 2D bismuth tungstate and unsupported hemin. HBWO shows layered structure with the interlayer spacing at ˜0.35 nm. In the photocatalytic process, hemin can not only act as an electron shuttle, also play an important role in oxygen transfer. Additionally, the synthesized HBWO composites exhibit nice binding affinities and high photocatalytic activity in tetracycline degradation. It is anticipated that beneficial use of synergistic effect of artificial enzyme and photocatalyst via HBWO composites can be a promising eco-friendly and efficient solution for addressing the environmental crisis.

Norfloxacin (NOR) in milk may influence mammalian cell replication and bring about a decrease in the efficiency for treating infection in humans. However, current techniques for detecting NOR usually require expensive instruments and trained personnel. In this work, we have developed a low-cost and simple method via paper-based fluorescent immunoassay for highly sensitive and selective detection of NOR in milk at picogram level. The NOR monoclonal antibody labeled with quantum dots is used as a detection probe to recognize the corresponding NOR, which can quantitatively detect NOR on paper-based devices. The detection limits in aqueous solution and milk are 1 pg/mL and 10 pg/mL, respectively. The developed paper-based method provides a cheap, sensitive, eco-friendly, and rapid approach for quantitative detection of trace NOR in milk, which may find wide applications in food safety inspection. Noteworthy, the method is especially suitable for applications at resource-limited and on-site settings.

Biochar, a green material that possesses high catalytic potential due to its persistent free radicals (PFRs), has attracted increasing attention in the removal of refractory pollutants from water. The influences of biomass types (bamboo, corn stalk, and pig manure) and its compositions (metals and phenolic compounds) on the formation of PFRs in biochar were investigated by electron paramagnetic resonance (EPR). It was found that the amounts of PFRs in biochar would decrease sharply with the decrease of the initial metals and phenolic compounds existed in biomass, and the effect of metals contents on PFRs formation was much greater than that of phenolic compounds contents. This finding was supported by the results obtained from elemental analysis and molar H/C analysis of three types of biochar, which suggested that pig-manure biochar (PM500) had the highest concentrations of PFRs of 14.13 × 1018 spins·g−1 due to the high content of metals and phenolic compounds in pig manure. The EPR trapping experiment and Linear sweep voltammetry (LSV) measurements in biochar/H2O2 systems showed that OH was the dominant reactive radical and electrons transfer pathways might be responsible for the activation of H2O2 by biochar. Possible degradation pathways of the tetracycline in biochar/H2O2 systems were also proposed. Besides, high degradation efficiency and good stability were observed in real wastewater application of the PM500/H2O2 system. These findings would provide a clearer insight into the formation mechanisms of PFRs in biochar, and also present a better strategy for biochar preparation and application in Fenton-like system.

Bismuth tungstate with different structures and morphologies show different properties. The structure and morphology have been proven to be critical factors to tune the electronic properties to influence photocatalytic performance. Notably, nano-structured bismuth tungstate were found to exhibit high activity in photocatalytic degradation process. Controllable fabrication on nano structures with desired morphology is indispensable to achieve the related properties well. However, a review that declare the correlation between the property and the fabrication, structure and morphology of bismuth tungstate is still absent. Therefore, we firstly summarize a series of recent fabrication methods for various dimensional nano structures of bismuth tungstate. Then the modification of nano-structured BWO to improve the photocatalytic performance are presented, including morphological manipulation, doping or substitution, solid solution fabrication, and compound formation. The mechanism of photocatalytic oxidation and reduction process over nano-structured bismuth tungstate is also explored, especially the role of radical species. Additionally, advanced environmental application are summarized. Finally, unresolved challenges and potential applications of nano-structured bismuth tungstate are presented for future research directions.

Density functional theory calculations have been performed to study the diverse reactivity of pentaphenylborole toward different epoxides. We systematically investigated the effect of substituents on epoxides for the preference/competition of three experimentally observed pathways, that is, intramolecular proton transfer, direct ring expansion via insertion of one epoxide molecule, and ring expansion via insertion of two epoxide molecules. Our calculations also predicted a high competitivity between the proton transfer and direct ring expansion pathways for the epoxide containing both alkyl and aryl substituents.

The 4-coordinated RuII chalcogenolate complexes [Ru(STipp)2(PPh3)2] (Tipp = 2,4,6-triisopropylphenyl, 1) and [Ru(SeMes)2(PPh3)2] (Mes = 2,4,6-trimethylphenyl, 2) have been synthesized, and their reactions with PhICl2 and organic azides have been studied. Complex 2 synthesized from [RuII(PPh3)3Cl2] and NaSeMes displays a seesaw structure with P–Ru–P and Se–Ru–Se bond angles of 103.43(13) and 145.26(6)°, respectively. Natural bond order analyses revealed that in each of 1 and 2, there are two n → σ* (donor–acceptor) π interactions between the chalcogen lone pairs and the Ru–P antibonding molecular orbitals. The calculated second-order perturbation interaction energies of the two interactions for 1 (20.5 and 18.3 kcal mol−1) are stronger than those of 2 (13.6 and 11.0 kcal mol−1), suggesting the thiolate ligand (TippS−) is a stronger π-donor than the selenolate ligand (MesSe−) with respect to RuII. Chlorination of 1 with PhICl2 afforded the dichloride complex [Ru(STipp)2Cl2(PPh3)] (3), which was hydrolyzed to the hydroxo complex [Ru(STipp)2(OH)Cl(PPh3)] (4) after column chromatography on silica in air. Treatment of 4 with HCl and methyl triflate gave 3 and [Ru(STipp)2(OH)(OTf)(PPh3)] (OTf = triflate, 5), respectively. Reactions of 1 and 2 with p-tolyl azide (p-tolN3) afforded the tetrazene complexes [Ru{N4(p-tol)2}(ER)2(PPh3)] (ER = STipp (6), SeMes (7)), whereas that with tosyl azide (TsN3) gave the imido complexes [Ru(κ2-NTs)(STipp)2(PPh3)] (ER = STipp (8), SeMes (10)). The short Ru–Nimido distances in 8 [1.883(3) A] and 10 [1.892(2) A] are indicative of multiple bond character. Treatment of 8 with TsN3 afforded the tetrazene complex [Ru(N4Ts2)(STipp)2(PPh3)] (9), but no cycloaddition was found between 10 and TsN3. Nucleophilic attack of the imido ligand in 10 with methyl triflate yielded the amido complex [Ru(κ2-NMeTs)(SeMes)2(PPh3)](OTf) (11). The crystal structures of 2, 4, 6, and 8–11 have been determined.

Highly-efficient materials and technologies for environmental pollutant treatment and hydrogen production are urgently needed in "green" 21st century. Notably, photocatalytic process over carbon nanomaterials (CNMs)-modified photocatalysts is an effective solution for these crises. CNMs (e.g., fullerenes, carbon nanotubes, graphene, carbon nanofibers, and carbon quantum dots) reveal remarkable morphological, mechanical, electrical and optical properties, which have been of significantly scientific and technological interest in photocatalysis. Until now, many efforts have been made to take advantage of these unique size- and surface-dependent properties of CNMs for photocatalytic process. In this review, we firstly summarize selective preparation of CNMs that has a great impact on their photocatalytic performance. Then we provide an updated outline of advanced photocatalytic application of CNMs in addressing both environmental pollution and hydrogen energy crisis. The difference in the role of various CNMs play in the enhancement of photocatalytic performance is also discussed. Lastly, we discuss the limitations of CNMs applied in photocatalysis or even wider fields. We hope this review will project a fast developmental path with providing a wide view of recent preparation methods, applications, prospects and challenges.

We report a phosphine-catalyzed trans hydroboration of alkynoate esters and amides. The reaction proceeds under mild conditions with exclusive ( E)-selectivity to afford ( E)-β-boryl acrylates and ( E)-β-boryl acrylamides in good to excellent yields. The reaction is tolerant of a variety of functional groups and allows efficient access to novel oxaboroles as well as a pargyline derivative (MAO inhibitor). Theoretical calculations suggest an internal hydride generates a phosphonium allenoxyborane followed by the formation of a key phosphonocyclobutene intermediate that collapses in a stereoselective, rate-limiting step.

A remarkable bioinspired EDDA-mediated method for the selective construction of biologically interesting and highly strained bridged methanodibenzo[b,f][1,5]dioxocin flavonoid scaffold was uncovered by starting from a variety of readily available acylphloroglucinol and 2-hydroxycinnamaldehyde substrates. This method merges a fascinating olefin isomerization/hemiacetallization/dehydration/[3 + 3]-type cycloaddition cascade reaction driven by an in situ generated chromenylium intermediate and provides a convenient and viable synthetic strategy for the efficient access of such flavonoid analogues.

CoWO 4 microrings assembled by nanorods were synthesized by a simple solvothermal method. The morphology and structure of the as-prepared unique CoWO 4 microrings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and high-resolution TEM (HRTEM). The as-prepared CoWO 4 sample with abundant active sites demonstrated good catalytic activity for glucose electrooxidation in alkaline solution. CoWO 4 modified glass carbon electrode (CoWO 4 -GCE) exhibited good electro-catalytic performance towards glucose detection, it offered a wider linear range, a low detection limit of 0.27 μM, high selectivity, and long-term operational stability. The results showed the as-prepared CoWO 4 microrings can be utilized to construct an enzyme-free glucose sensor based on GCE.

The reactions of organic azides with diaryl(dihalo)diboranes(4) were explored, resulting in the observation of a number of surprising reactivity patterns. The reaction of phenyl azide with 1,2-diaryl-1,2-dihalodiboranes(4) resulted in the formation of five-membered rings comprising diboryl-triazenes with retention of the boron-boron bond, while the reaction of the peculiar 1,1-di(9-anthryl)-2,2-difluorodiborane(4) with phenyl azide yielded a six-membered ring bearing a diboryl-triazene, whereby the B-B bond was ruptured by the insertion of an arylnitrene-like reactive intermediate. Both types of heterocycles feature unprecedented connectivity patterns and are very rare examples of boryl triazenes beyond the more common 1,2,3-triazolatoboranes. They are also the product of a unique type of aryl migration from a boron center to the phenyl azide γ-nitrogen center. Lastly, the substitution of 1,2-diaryl-1,2-dihalodiboranes(4) with azide groups, using trimethylsilyl azide as the transfer reagent, yielded boryl-tetrazaboroles and diboryldiazadiboretidines (as side-products), invoking the intermediacy of the first N-boryl-substituted iminoboranes, which are BN isosteres of monoborylated alkynes. The synthetic results are complemented with mechanistic proposals derived from quantum-chemical calculations.

Using a single test to comprehensively evaluate multiple cardiac biomarkers for early diagnosis and prevention of acute myocardial infarction (AMI) has faced enormous challenges. Here, we have developed paper-based fluorogenic immunodevices for multiplexed detection of three cardiac biomarkers, namely, human heart-type fatty acid binding protein (FABP), cardiac troponin I (cTnI), and myoglobin, simultaneously. The detection is based on a strategy using zinc oxide nanowires (ZnO NWs) to enhance fluorescence signals (∼5-fold compared to that on pure paper). The immunodevices showed high sensitivity and selectivity for FABP, cTnI, and myoglobin with detection limits of 1.36 ng/mL, 1.00 ng/mL, and 2.38 ng/mL, respectively. Additionally, the paper-based immunoassay was rapid (∼5 min to complete the test) and portable (using a homemade chamber with a smartphone and an ultraviolet lamp). The developed devices integrated with ZnO NWs enable quantitative, sensitive, and simultaneous detection of multiple cardiac biomarkers in point-of-care settings, which provides a useful approach for monitoring AMI diseases and may be extended to other medical diagnostics and environmental assessments.

In this paper, we report a simple, feasible and low-cost method to fabricate self-standing metallic materials using cellulose-based biomass as sacrificial templates. This process involves the impregnation of metallic precursors to the cellulose fibers of biomass templates and the transformation of the precursors to corresponding metals or metal oxides (as well as the removal of the cellulose framework) at an elevated temperature. The structures of the metallic materials as fabricated take the form of architectures of biomass templates (e.g., chromatography paper, medical absorbent cotton, catkins of reed, seed balls of oriental plane, and petals of peach blossom), and the various kinds of metals and metal oxides fabricated with these templates include silver, gold, anatase, cupric oxide, zinc oxide, etc. We have demonstrated photocatalytic and bactericidal applications of such metallic materials, and they should find more applications in electronics, catalysis, energy storage, biomedicine and so on.

Cytorhizins A–D, four novel polyketide heterodimers, were isolated from the endophytic fungus Cytospora rhizophorae A761. These new compounds shared an unprecedented 6/6/5/6/8 or 6/6/5/6/7 pentacyclic ring system and fused as a fascinating cagelike skeleton, embodying by a polyoxygenated isopentyl unit and a highly structure-combined benzophenone scaffold. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Moreover, compounds 1–4 were evaluated for in vitro cytotoxicity and antimicrobial activity.

Five new compounds including two stilbenes, designated thujasutchins A (1) and B (2), two phenolic compounds namely thujasutchins C (3) and D (4), as well as one sesquiterpene thujasutchin E (5), were isolated from the 95% ethanolic extract from the trunks and roots of Thuja sutchuenensis. Their structures were determined by means of extensively spectroscopic analysis including UV, IR, HRESIMS, 1H and 13C NMR (COSY, HSQC, HMBC). Moreover, compounds 1, 3-5 were evaluated for in vitro cytotoxic activities against SF-268, MCF-7, HepG-2, and A549 tumor cell lines.

A novel three-dimensional (3D) vertical-flow paper-based device (3VPD), integrated with a sandwich-type fluorescent immunoassay, was developed for multiplexed detection of cancer biomarkers simultaneously based on the principle of origami. The developed 3VPD, composed of a sample layer, a splitting layer, and a test layer, could be fabricated simply by wax-printing on paper at a large scale. Herein, a vertical-flow immunoassay was introduced into the device, in which fluorescein isothiocyanate labeled antibodies were coated on the splitting layer and mouse monoclonal capture antibodies were functionalized on the test layer. The proposed 3VPD showed high sensitivity and selectivity for detecting three cancer biomarkers, carcinoembryonic antigen (CEA), a-fetoprotein (AFP), and cancer antigen 199 (CA199) with detection limits of 0.03 ng/mL, 0.05 ng/mL, and 0.09 U/mL in human serum, respectively. The results obtained in human serum were compatible with the reference values which were acquired from parallel single-analyte. The developed 3VPD provides a new strategy to develop an inexpensive and sensitive approach for simultaneous detection of multiple analytes and comprehensive clinical diagnosis by a single test.

Three new prenylated stilbenes, named as cajanusins A-C (1-3), and one new natural product cajanusin D (4), along with six known derivatives (5-10) were isolated from the leaves of Cajanus cajan. Their structures were fully elucidated by means of extensive spectroscopic methods and comparison with data in the reported literatures. The new compounds of 1 and 2 were evaluated for in vitro cytotoxic activities against a panel of human cancer cell lines.