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Herein, we describe a DABCO-catalyzed [4 + 2] annulation between 5-methylenehex-2-ynedioates and electron-deficient olefins to afford functionalized cyclohexadienes in good yields under mild conditions. The use of β- and ε-carbons of the substrates for C-C bond formation is distinct from previous reports showing a substrate-controlled divergent reactivity. The annulation is believed to proceed in domino cyclization initiated by a cross Rauhut-Currier reaction.

A highly efficient cascade cyclization of phenidones and enynones has been developed via a Ru(II)-catalyzed C-H activation initiated indole formation/Diels-Alder reaction/iminium ion cyclization sequence, which afforded hexacyclic indolines as single diastereomer in good to excellent yields with a broad substrate scope under mild conditions. The reaction features the simultaneous generation of five new chemical bonds and four new rings in one pot, providing a rapid and concise approach toward polycyclic indoline alkaloids and their analogues.

Herein we describe a phosphine-catalyzed internal redox [4 + 2] annulation of 1,4-enynoates with electron-deficient alkenes, in which the γ- and φ-C(sp3)-H of the enynoates are formally oxidized for the annulation while the alkynyl moiety is converted to an alkene. The reaction offers an efficient synthesis of highly functionalized cyclohexenes in moderate to good yields with exclusive regioselectivity and high diastereoselectivity under mild conditions.

A rhodium-catalyzed diastereoselective formal [5 + 2] annulation of indoles with cyclohexadienone-containing 1,6-enynes has been established via indole 2,3-difunctionalization. The reaction, probably proceeding through tandem indole C2-H alkenylation and intramolecular Friedel-Crafts alkylation relay, provides rapid construction of indole-fused oxepines in good to excellent yields with a broad substrate scope. This method also features concomitant construction of cis-hydrobenzo[b] oxepine scaffolds, a core unit found in numerous natural products of important biological activities.

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C3 synthon for formal cycloadditon reactions.

Continuous emergence of persistent organic pollutants perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in various water bodies around the world poses a serious threat to the global ecosystem. The exploration of advanced detection/removal techniques to monitor/treat such type of toxicants is urgently required. Herein, we unveiled a donor-acceptor type conjugated polymer PF-DBT-Im as a first-of-its-kind ratiometric fluorescent probe for visual, amplified, and specific monitoring of PFOA and PFOS with ultra-low detection limits of 6.12 nM (PFOA) and 14.3 nM (PFOS), respectively. PF-DBT-Im undergoes strong aggregation after binding with PFOA/PFOS as evident by transmission electron microscopy, zeta potential measurements, and dynamic light scattering studies. This promotes interchain Förster resonance energy transfer process to endorse an obvious emission color change from blue-to-magenta under ultraviolet lamp excitation. Consequently, a smartphone-integrated portable device is fabricated for realizing rapid and on-site detection of PFOA/PFOS. Besides, a new class of magnetic adsorbent Fe

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C

Multiwall carbon nanotubes (MWCNTs) were non-covalently functionalized by a uniform layer of a porphyrin–Sn network (denoted as MPT) via a facile one-pot solvothermal synthesis for enhancing protei...

An efficient Cp*RhIII-catalyzed formal C(sp3)–H activation/spiroannulation of alkylidene Meldrum’s acids with alkynes has been developed using catalytical Cu(OAc)2 and air as the oxidant. This reac...

An efficient regioselective and stereoselective cascade annulation of indoles with alkynediones has been demonstrated via a Cp*RhIII-catalyzed indole C2–H activation by using N-carboamide directing groups in good to excellent yields with a broad substrate scope, which further realized the C2 and C3 difunctionalization of indoles in one-pot. This methodology simultaneously provides a novel and straightforward approach to free (NH) tetrahydrocarbazoles with continuous quaternary carbons and pyridoindolones, which are valuable intermediates in total synthesis of the related indole alkaloids.

Nowadays, the recovery of added-value compounds by pre-treatment and extraction has become imperative in the recycling and transformation of bio-waste. Hence, to achieve efficient bio-waste recycling and avoid the drawbacks of solvent and time consumption in traditional pre-treatment, a green and facile method of efficient separation and enrichment of luteolin (LTL) from honeysuckle leaves has been developed via the green synthesis of novel magnetic molecularly imprinted polymers (Fe3O4-LTL-MIPs). Fe3O4-LTL-MIPs were prepared in aqueous solution using polyethyleneimine and dopamine as eco-friendly bifunctional monomers via layer-by-layer assembly onto the amino-modified Fe3O4 carriers. The thin sandwich-biscuit-like imprinting layer in Fe3O4-LTL-MIPs provides sufficient binding sites with enhanced uniformity and accessibility for the template molecules, thus facilitating excellent recognition ability and rapid mass transfer. The obtained nanomaterials show homogeneous morphology, good crystallinity, satisfactory superparamagnetism, ultra-fast adsorption kinetics, high recognition ability, and excellent reusability. Moreover, Fe3O4-LTL-MIPs as solid-phase extraction adsorbents exhibit high efficiency for the separation and enrichment of LTL from the honeysuckle leaves combined with HPLC analyses. Therefore, the Fe3O4-LTL-MIPs could be potentially exploited as a feasible and efficient way to meet the goals of green chemistry for selective recycling and enriching target compounds from complicated bio-waste matrices.

A highly efficient Ru(II)-catalyzed regio- and stereospecific hydro-oxycarbonylation of unsymmetrical internal alkynes bearing a difunctional 2-pyridyloxy directing group with carboxylic acids has been developed, which provides allylic (

Designing efficient room-temperature phosphorescence (RTP) carbon dots (C-dots) without the need of an additional matrix is important for various applications. Herein, matrix-free and highly efficient C-dots with yellow-green RTP emission have been successfully synthesized towards information encryption and decryption. Phytic acid (PA) and triethylenetetramine are used as molecular precursors, and a facile microwave-assisted heating method is selected as synthesis method. The obtained C-dots exhibit a maximum phosphorescence emission at around 535 nm under an excitation wavelength of 365 nm and a long average lifetime up to 750 ms (more than 9 s to the naked eye). PA containing six phosphate groups and serving as P source plays a significant role in producing the RTP C-dots. Furthermore, potential applications of the RTP C-dots in the field of information encryption and decryption are successfully demonstrated.

The reactivity of allylic phosphorus ylides generated in situ from alkoxycarbonylmethylenephosphoranes and propiolates is investigated toward isocyanates and aromatic aldehydes, which leads to one-pot multicomponent benzannulations for efficient synthesis of polysubstituted anilines and biaryls, respectively. The mechanism may involve a tandem [2+2] cycloaddition/fragmentation/Wittig/cyclization/elimination/aromatization sequence.

We report a phosphine-catalyzed ring opening of electron-deficient alkylidenecyclopropanes (ACPs) to generate allylic phosphonium zwitterions that resemble the well-studied phosphine-allene adducts but exhibit distinct properties. The potent reactivity of these intermediates has been demonstrated in three types of substrate-controlled phosphine-catalyzed rearrangements of alkylidenecyclopropylketones, which chemoselectively afford tri- and tetrasubstituted furans, and trisubstituted dienones in good yields.

Premature senescence after anthesis reduces crop yields. Delaying leaf senescence could maintain photosynthetic activity for a longer period and lead to a higher photosynthetic rate. Recent studies have provided some insights into the interaction between cytokinin and nitrogen (N) in the regulation of plant development. In the present study, foliar application of exogenous 6-benzylaminopurine (6-BA) and lovastatin, an inhibitor of cytokinin synthesis, was combined with three N rates [0 kg ha−1 (low nitrogen, LN), 240 kg ha−1 (normal nitrogen, NN), and 360 kg ha−1 (high nitrogen, HN)] in two wheat cultivars, Wennong 6 (with a staygreen phenotype) and Jimai 20 (with a non-staygreen phenotype). Flag leaf senescence was assessed using a Gompertz growth curve. Grain mass, dry matter accumulation and distribution, total N of flag leaf, and concentrations of zeatin riboside (ZR) and abscisic acid (ABA) were also used to evaluate the functional characteristics of flag leaves. Grain mass was negatively correlated with initial senescence rate (r0) and duration of rapid chlorophyll loss (Chlloss), whereas it was positively correlated with maximum senescence rate (rmax), average senescence rate (raver), persistence phase (Chlper), total duration of flag leaf (Chltotal) and inflection point cumulative temperature (M). Compared to Jimai 20, Wennong 6 had larger raver, Chlper, and Chltotal. The concentration of ZR was highest under the 6-BA × NN treatment, followed by the 6-BA × HN and 6-BA × LN treatments. However, the concentration of ABA showed the opposite trend. It was concluded that the staygreen phenotype Wennong 6 was associated with greater grain mass and altered cytokinin metabolism and could be classified as a functional staygreen type. Foliar application of 6-BA interacting with N at the NN level (240 kg ha−1) may be a beneficial strategy for improving grain yield of wheat by regulating endogenous hormones and the flag leaf senescence process. Increasing endogenous cytokinin promoted the transport of dry matter to grain. Keywords: Triticum aestivum L., Interaction, Cytokinin, Nitrogen, Staygreen wheat, Flag leaf senescence

The common elution process of molecularly imprinted polymers (MIPs) is carried out in an acidic medium, which greatly affects the stability and reusability of synthetic MIPs, especially for magnetic MIPs. In this study, we fabricated an acid-resistant imprinted layer formed by phase-transitioned lysozyme on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle, which often coexists with structural analogs. The newly designed acid-resistant imprinted layer can not only protect the internal magnetic core from denudation and dissolution, but also maintain the integrity of the imprinted layer during the elution process. The resultant magnetic MIPs exhibited good stability with no change on morphology after the repeatedly eluting process, and satisfactory reusability that can be used at least ten adsorption-desorption cycles with almost no decrease for adsorption capacity. In addition, the resultant materials possess satisfactory magnetism, uniform morphology with typical core-shell structure, stable crystallization, and good adsorption performance showing on high adsorption amount (10.82 mg g−1), fast kinetic equilibrium time (as short as 30 min), and satisfactory selectivity (IF = 2.85, SC > 1.5). At last, the obtained magnetic MIPs as adsorbents coupled with HPLC were successfully used to selective extract CGA in Honeysuckle samples with the high recoveries in the range of 92.0–104.4%, and the contents of CGA in Honeysuckle samples from the different origin are calculated in the range of 0.98%–1.24%.

A synergistic imprinting strategy of covalent and non-covalent interactions is proposed to prepare magnetic molecularly imprinted polymers (DI-MMIPs) for highly selective separation of procyanidin B2 (PC) from grape seed samples. Dopamine and 3-amino-phenylboronic acid as cooperative functional monomers endow the imprinted sites with synergistic tailoring. Benefiting from the synergistic effect, the DI-MMIPs exhibit enhanced imprinting performance with high adsorption capacity (27.71 mg g-1), fast kinetic equilibrium time (within 30 min), outstanding selectivity (IF = 5.8, SC > 3.2), and satisfactory regeneration ability. In addition, the DI-MMIPs possess good magnetism, uniform morphology with typical core-shell structure, and stable crystallization. Furthermore, the established DI-MMIPs coupled with HPLC-UV (~ 280 nm) method has a wide linearity range of 0.05-200 μg mL-1 with correlation coefficient of 0.9997, high recoveries (> 93.1%) with RSDs from 2.9 to 5.5%, and low LOD (0.0008 μg mL-1). Consequently, this work provides an effective and easily tailored way to fabricate magnetic imprinted nanomaterials with both rapid recognition rate and high selectivity and thus holds great promise to realize the extraction and detection of PC from real samples.

A three-component reaction between one molecule of phosphorus ylides (P-ylides) and two molecules of isocyanates for the rapid assembly of 2-amino-3-carboxylate-4-quinolones is described. The mechanism may involve the addition of a P-ylide to an isocyanate followed by 1,3-H shift to form a carbamoyl stabilized P-ylide. The intermediate then reacts with another aryl isocyanate via Wittig/ketenimine-ketene rearrangement/6π-electrocyclization/1,3-H shift to finally afford the 4-quinolones.

A novel type of uniform magnetic imprinted nanomaterial for the recognition of bovine serum albumin (BSA) was prepared by anchoring MIP shells on the surface of silica deposited Fe3O4 NPs via a surface imprinting process and two-stage core–shell sol–gel polymerization. The resulting magnetic nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and a vibrating sample magnetometer (VSM). The measurements indicated that the as-synthesized nanospheres exhibited good dispersion, high crystallinity, and satisfactory superparamagnetic properties. Moreover, the obtained Fe3O4@BSA–MIPs had a high saturation magnetization (43.82 emu g−1), which allowed them to be easily separated from solution by means of an external magnetic field. The thickness of the imprinted polymer layer was approximately 5 nm, which would be effective for the mass transport between the solution and the surface of Fe3O4@BSA–MIPs. The kinetic adsorption experiment showed that the imprinted nanomaterials could reach equilibrium within 15 min and be well described by the second-order kinetics model, indicating chemical adsorption might be the rate-limiting step. Meanwhile, the imprinting factor and selectivity coefficient of the Fe3O4@BSA–MIPs were as high as 16.4 and 4.65, displaying excellent selectivity towards BSA. In addition, the resulting imprinted polymers were without obvious deterioration after ten adsorption–desorption cycles and different batches of which exhibited excellent reproducibility. Successful application in the selective separation and enrichment of BSA from a bovine blood sample and good recovery after a reasonably mild elution suggested that the Fe3O4@BSA–MIPs could specifically capture BSA from a real complex matrix and had potential value in practical applications.

In this work, the core-shell bovine hemoglobin (BHb)-imprinted superparamagnetic nanoparticles (Fe

The efficiency of energy storage technologies such as water splitting and metal-air batteries is limited by the sluggish dynamics of the oxygen evolution reaction (OER). Herein, we report a galvanic replacement-mediated method for in-situ growth of iron-nickel nitride on carbon nanotubes (CNTs) as a powdery catalyst for OER. This in-situ grown structure creates intimate interaction between the active substance of Fe2Ni2N and CNTs so as to accelerate charge transfer in the catalytical interface. First-principles calculations reveal that the Fe2Ni2N is intrinsically metallic, and the contribution mainly derives from the Fe atoms at corner sites of crystal structures. A good synergistic effect between metallic Fe2Ni2N with excellent intrinsic activity and conductive CNTs lead to outstanding electrochemical performance with a low overpotential (η10 mAcm-2 = 282 mV) and Tafel slope (38 mV dec−1), as well as good long-term stability.

The nitrogen-doped porous carbon nanofibers decorated with CoxOy nanoparticles (NPCF) have been synthesized by a facile electrospun method followed by calcination at 950 °C in N2. It is interesting that the self-evaporation of zinc precursor from inside to outside can form the stable pore channels frame structure inside the carbon composites, which can be beneficial to the migration of the ion. Moreover, the pore channels density can be controlled by varying the amount of zinc nitrate. When the NPCF applied as anode materials, it exhibits a high reversible capacity of 983.5 mAh g−1 after 400 cycles at 1000 mA g−1. And it also deliveries an outstanding rate performance, which can be stabilized at ∼1488, ∼1172, ∼957.5, and ∼802.4 mAh g−1 when increasing the discharge/charge current density to 100, 300, 600, 1200 mA g−1, respectively.

Rutin (RT), a widely distributed natural flavonoid compound, has been generally utilized as an important active ingredient owing to its considerable biomedical and economic value. Inspired by the structure features of densely-packed bayberry and well-orientated honeycomb, a novel type of magnetic molecularly imprinted polymers (HB-TI-MMIPs) with abundant high-affinity and uniformly-distributed binding sites was rationally constructed for the selective enrichment of RT from Sophora japonica. The polymerization conditions, physicochemical properties, and adsorption performance of the imprinted nanomaterials were systematically investigated. The optimized HB-TI-MMIPs display a high adsorption capacity, fast adsorption rate, and satisfactory selectivity towards RT. Meanwhile, the proposed analytical methodology using HPLC, with HB-TI-MMIPs as adsorbents, successfully applied to enrich and detect RT from Sophora japonica with high recoveries (87.2-94.6%) and good RSDs (lower than 4.3%). Therefore, the fabricated HB-TI-MMIPs with a fast magnetic responsivity and desirable adsorption performance would be attractive in plant active ingredients extraction fields.

A Cp*RhIII -catalyzed annulative carbooxygenation of challenging 1,1-disubstituted alkenes triggered by C-H activation of N-aryloxyacetamides has been established, which affords 2,3-dihydrobenzofuran derivatives with a quaternary carbon center in good to excellent yields under mild redox-neutral conditions. An amide group on the alkenes is essential for the process, and may inhibit the β-H elimination from C(sp3)-Rh species by saturating the rhodium center through coordination. Furthermore, mechanistic insights obtained from control experiments suggest a mechanism involving a RhIII -RhV -RhIII catalytic cycle.

The development of new methods for the detection of redox cycle is important for biological and clinical diagnoses. Here, a new cyclometalated iridium complex, (4-(2-pyridyl) benzaldehyde)

To overcome the limited drug loading capacity of magnetic nanopharmaceuticals arising from the relatively large mass of the metal core, a high-loading drug delivery system based on amino-functionalized Fe3O4 magnetic nanospheres modified by hyperbranched phenylboronic acid (HPBA-Fe3O4) were prepared for the first time. The obtained nanomaterials were characterized by transmission electron microscopy, Fourier transform infrared, zeta potential, elemental analysis, vibrating sample magnetometry and X-ray diffraction analysis, and the results showed that hyperbranched phenylboronic acid (HPBA) were successfully grafted onto the surface of the magnetic nanospheres. The polymerization conditions, adsorption and desorption performance, and tumor-targeting ability of HPBA-Fe3O4 was investigated in detail through chemical and biological experiments. The drug loading amount and capacity of HPBA-Fe3O4 are 271.3 mg/g and 27.13%, respectively, which are 2.26 and 3.27 times greater than those of PBA-Fe3O4 and PEI-Fe3O4, and the thermodynamic fitting results further demonstrate the high drug loading ability of HPBA-Fe3O4. In vitro studies performed in U-87 MG malignant glioma cells and astrocytes via light and fluorescence microscopy analyses, cell counting kit-8 assays, and HPLC tests confirm the pH-sensitive release and tumor-targeted drug delivery capabilities of HPBA-Fe3O4. The facile fabrication of hyperbranched magnetic nanomaterials could be an alternative solution for designing high-loading, tumor cell-targeting and pH-responsive DDSs with high-mass cores.

In this work, a novel amphiphilic magnetic nanocomposite (Fe3O4@A-O) used for the adsorption of phthalate esters was synthesized by a simple sol-gel surface modification method, during which hydrophilic amino groups of 3-aminopropyltriethoxylsilane and hydrophobic alkyl chains of N-octyltrimethoxysilane were modified onto Fe3O4 nanoparticles. Morphologies and surface structures of as-prepared magnetic nanomaterials were characterized in detail. The preparation, adsorption, and desorption conditions of Fe3O4@A-O were investigated systematically and the adsorption mechanism was discussed. The Fe3O4@A-O exhibits quite fast adsorption for six phthalate esters, which only takes two minutes and is 10 ∼ 720 times shorter than other reported adsorbents. Theoretical adsorption capacities of Fe3O4@A-O for dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and didecyl phthalate are >1000 mg/g according to the Freundlich fitting. With ethanol as desorption solvent, it only takes one minute to reach desorption equilibrium. In addition, Fe3O4@A-O can be collected from aqueous solution with an applied magnet in just three seconds, and it shows satisfactory stability and reusability after recycling 10 times. The developed amphiphilic adsorbent exhibits great promises in the removal of phthalate esters because of its easy preparation, excellent adsorption and desorption performances, rapid magnetic separation, and good reusability.

Supplemental material, ASP861573 Supplemental Material for Cyclometalated Iridium Complex as Off–On–Off Reversible Photoluminescence Probe for Redox Cycle HSO3-/H2O2 in Living Cells by Hetong Qi, Xiaojia Zhao, Yuhai Tang, Manping Qian, Hongfang Gao and Honglan Qi in Applied Spectroscopy