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The Si window is the most widely used internal reflection element (IRE) for electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), yet local chemical etching on Si by concentrated OH - anions bottlenecks the reliable application of this method in strong alkaline electrolytes. In this report, atomic layer deposition of a 25 nm nonconductive TiO 2 barrier layer on the reflecting plane of a Si prism is demonstrated to address this challenge. In situ ATR-SEIRAS measurement on a Au film electrode with the Si/TiO 2 composite IRE in 1 M NaOH reveals reversible global spectral features without spectral distortion at 1000-1300 cm -1 , in stark contrast to those obtained with a bare Si window. By applying this structured ATR-SEIRAS, ethanol electrooxidation on a Pt/C catalyst in 1 and 5 M NaOH is explored, manifesting that such high pH values prevent the adsorption of as-formed acetate in the C2 pathway but not that of CO intermediate in the C1 pathway.

In recent decades, whole-cell biocatalysis has played an increasingly important role in the food, pharmaceutical, and energy sector. One promising application is the use of ethanologenic yeast displaying minicellulosomes on the cell surface to combine cellulose hydrolysis and fermentation into a single step for consolidated bioprocessing. However, cellulosic ethanol production using existing yeast whole-cell biocatalysts (yWCBs) has not reached industrial feasibility due to their inefficient cellulose hydrolysis. As prior studies have demonstrated enzyme density on the yWCB surface to be one of the most important parameters for enhancing cellulose hydrolysis, we sought to maximize this parameter at both the population and single-cell levels in yWCBs displaying tetrafunctional minicellulosomes. At the population level, enzyme density is limited by the presence of a nondisplay population constituting 25-50% of all cells. In this study, we identified the cause to be plasmid loss and successfully eliminated the nondisplay population to generate compositionally uniform yWCBs. At the single-cell level, we demonstrate that enzyme density is limited by molecular crowding, which hinders minicellulosome assembly. By adjusting the integrated gene copy number, we obtained yWCBs of tunable enzyme display levels. This tunability allowed us to avoid the crowding-limited regime and achieve a maximum enzyme density per cell. As a result, the best strain showed a cellulose-to-ethanol yield of 4.92 g/g, corresponding to 96% of the theoretical maximum and near-complete conversion (∼96%) of the starting cellulose (1% PASC). Our holistic engineering strategy that combines a population and single-cell level approach is broadly applicable to enhance the WCB performance in other biocatalytic cascade schemes.

Aqueous supramolecular long-lived near-infrared (NIR) material is highly attractive but still remains great challenge. Herein, we report cucurbit[8]uril confinement-based secondary coassembly for achieving NIR phosphorescence energy transfer in water, which is fabricated from dicationic dodecyl-chain-bridged 4-(4-bromophenyl)-pyridine derivative (G), cucurbit[8]uril (CB[8]), and polyelectrolyte poly(4-styrene-sulfonic sodium) (PSS) via the hierarchical confinement strategy. As compared to the dumbbell-shaped G, the formation of unprecedented linear polypseudorotaxane G⊂CB[8] with nanofiber morphology engenders an emerging phosphorescent emission at 510 nm due to the macrocyclic confinement effect. Moreover, benefiting from the following secondary assembly confinement, such tight polypseudorotaxane G⊂CB[8] can further assemble with anionic polyelectrolyte PSS to yield uniform spherical nanoparticle, thereby significantly strengthening phosphorescence performance with an extended lifetime (i.e., 2.39 ms, c.f., 45.0 μs). Subsequently, the organic dye Rhodamine 800 serving as energy acceptor can be slightly doped into the polyelectrolyte assembly, which enables the occurrence of efficient phosphorescence energy transfer process with efficiency up to 80.1% at a high donor/acceptor ratio, and concurrently endows the final system with red-shifted and long-lived NIR emission (710 nm). Ultimately, the as-prepared assembly is successfully exploited as versatile imaging agent for NIR window labeling and detecting in living cells., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Clostridium perfringens is a major cause of infectious foodborne disease, frequently associated with the consumption of raw and undercooked food. Despite intensive studies on clarifying C. perfringens pathogenesis, the molecular mechanisms of host-pathogen interactions remain poorly understood. In soft tissue and mucosal infection models, Gpr120 - / - mice, G protein-coupled receptor 120 (GPR120), are more susceptible to C. perfringens infection. Gpr120 deficiency leads to a low survival rate (30 and 10%, p < 0.01), more bacterial loads in the muscle (2.26 × 10 8 ± 2.08 × 10 8 CFUs/g, p < 0.01), duodenum (2.80 × 10 7 ± 1.61 × 10 7 CFUs/g, p < 0.01), cecum (2.50 × 10 8 ± 2.05 × 10 8 CFUs/g, p < 0.01), and MLN (1.23 × 10 6 ± 8.06 × 10 5 CFUs/g, p < 0.01), less IL-18 production in the muscle (8.54 × 10 3 ± 1.20 × 10 3 pg/g, p < 0.01), duodenum (3.34 × 10 3 ± 2.46 × 10 2 pg/g, p < 0.01), and cecum (3.81 × 10 3 ± 5.29 × 10 2 pg/g, p < 0.01), and severe organ injury. Obviously, GPR120 facilitates IL-18 production and pathogen control via potassium efflux-dependent NOD-like receptor family pyrin domain-containing 3 (NLRP3) signaling. Mechanistically, GPR120 interaction with NLRP3 potentiates the NLRP3 inflammasome assembly. Thus, this study uncovers a novel role of GPR120 in host protection and reveals that GPR120 may be a potential therapeutic target for limiting pathogen infection.

Photocatalysts for regeneration of reduced nicotinamide adenine dinucleotide (NADH) usually work with continuous lighting and electron mediators, which causes impracticability under dark conditions, risk of NADH reoxidation, and complex separation. To solve these problems, we present a new catalyst of tiny Pt nanoparticles photodeposited on chromium-doped zinc gallate (CZGO@Pt). Upon being light-triggered, the photogenerated electrons are stored in the traps of CZGO and then gradually released and transferred by Pt to directly reduce NAD + after stoppage of illumination. Three lighting modes are compared to demonstrate the feasibility and advantage of this light-triggered dark catalysis. Within 4 h of reaction, the in-the-dark NADH yield reaches 75.0% under prelighting CZGO@5%Pt and it reaches 80.0% under prelighting CZGO@5%Pt and triethanolamine (TEOA). However, the NADH yield is only 53.5% under continuous lighting of CZGO@5%Pt, TEOA, and NAD + . Consequently, the light-triggered dark catalytic regeneration of NADH not only saves energy and operates easily but also significantly elevates the NADH yield. It thus would secure wide interests and applications in places where no light or only intermittent light is available.

Ethanol, as a sustainable biomass fuel, is endowed with the merits of theoretically high energy density and environmental friendliness yet suffers from sluggish kinetics and low selectivity toward the desired complete electrooxidation (C1 pathway). Here, the localized surface plasmon resonance (LSPR) effect is explored as a manipulating knob to boost electrocatalytic ethanol oxidation reaction in alkaline media under ambient conditions by appropriate visible light. Under illumination, Au@Pt nanoparticles with plasmonic core and active shell exhibit concurrently higher activity (from 2.30 to 4.05 A mg Pt -1 at 0.8 V vs RHE) and C1 selectivity (from 9 to 38% at 0.8 V). In situ attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) provides a molecular level insight into the LSPR promoted C-C bond cleavage and the subsequent CO oxidation. This work not only extends the methodology hyphenating plasmonic electrocatalysis and in situ surface IR spectroscopy but also presents a promising approach for tuning complex reaction pathways.

In situ spectroscopic characterization of the interfacial structure of an organic additive at a Cu electrode is essential for a mechanistic understanding of Cu superfilling at the molecular level. In this work, we demonstrate wide-frequency attenuated total reflection surface-enhanced infrared absorption spectroscopy (wf-ATR-SEIRAS) to elucidate the dissociative adsorption of bis(sodium sulfopropyl)-disulfide (a typical accelerator) on a Cu electrode in conjunction with the electrochemical quartz crystal microbalance measurement and modeling calculations. The wf-ATR-SEIRAS clearly identifies the peaks featuring the sulfonate and methylene groups as well as the C-S sulfonate and C-S thiol vibrations of the adsorbate. Analysis of relative peak intensities from 1100 to 650 cm -1 reveals a more tilted alkyl chain axis for the thiolate on Cu than that on Au, which is supported by comparative density functional theory calculations. This work opens a new avenue for the wf-ATR-SEIRAS to study interfacial structures of electroplating additives related to advanced microelectronics manufacture.

Exploring effective sensors for detecting possible hazards in a water system are greatly significant. This work proposed a strategy for stable and effective bifunctional sensors via incorporating hourglass-type phosphomolybdates into metal-organic fragments to construct a high-dimensional framework. Two hourglass-type phosphomolybdate-based electrochemical sensors toward heavy metal ion Cr(VI) and tetracycline (TC) detection were designed with the formula [Co II 2 (H 2 O) 4 Na I 2 ][Co II (Hbpe)][Na I (bpe) 1.5 ]{Co II [P V 4 Mo V 6 O 31 H 6 ] 2 }·9H 2 O ( 1 ) and [Co II (H 2 O) 4 Na I 3 ][Co II (Hbpe)][Co II (bpe)]{Co II [P V 4 Mo V 6 O 31 H 6 ] 2 }·9H 2 O ( 2 ) [bpe = 1,2-di(4-pyridyl)ethylene]. Structural analysis showed that hybrids 1 and 2 possess three-dimensional POM-supported network features with favorable stability and exhibit reversible redox properties. Experiments found that this kind of hybrids as efficient sensors have excellent electrochemical performance toward Cr(VI) detection with high sensitivities of 0.111 μA·μM -1 for 1 and 0.141 μA·μM -1 for 2 , fast response time of 1 s, and low detection limits of 30 nM for 1 and 27 nM for 2 , which far meet the standard of WHO for drinking water. Moreover, hybrids 1-2 also exhibit fast responses to TC detection with sensitivities of 0.0073 and 0.022 μA·mM -1 and detection limits of 0.426 and 0.084 mM. This work offers a novel strategy for the purposeful design of efficient POM-based electrochemical sensors for accurate determination of contaminants in a practical water system.

A balanced detection of both adsorbates and dissolved species is very important for the clarification of the electrochemical reaction mechanism yet remains a major challenge for different modes of electrochemical infrared (IR) spectroscopy. Among others, conventional attenuated total reflection-surface-enhanced IR absorption spectroscopy (ATR-SEIRAS) is far less sensitive to low-concentration solution species than to surface species. We report herein an electrochemical wide-frequency ATR-SEIRAS with a novel thin-layer flow cell design, fulfilling the simultaneous detection of the variations of surface and solution species. This setup consists of a silicon wafer (with one side micromachined and the other side metallized), a thin-layer electrolyte structure with tunable thickness and flow rate, and a tilt-correction system based on laser collimation, enabling a well-controlled mass transport within the electrolyte layer and the spectral differentiation of solution species from adsorbates. Using acidic methanol oxidation on a Pt film electrode as a model system, besides SEIRA bands for adsorbed CO and formate intermediates, IR spectral signals for dissolved products CO 2 , formic acid, and methyl formate can be readily identified for a quiescent electrolyte layer of ∼20 μm, which are otherwise undetected with conventional ATR-SEIRAS, as indicated by the trend of spectral features with increasing thickness or flow rate.

Macrocyclic supramolecular coassembly is the current research hotspot for tumor treatment. Herein, we report a multivalent supramolecular coassembly strategy, which not only acquires long-time phosphorescent labeling of mitochondrial aggregation but also strongly enhances chemotherapeutic efficiency against drug-resistant tumors. The mitochondrial aggregation depends on cucurbit[8]uril-mediated cross-linkage of the hyaluronic acid polymer grafted by 4-bromophenylpyridium and mitochondrion-targeting peptide (HABMitP) residing on the mitochondria, taking advantage of the 2:1 homoternary host-guest complexation between cucurbit[8]uril and 4-bromophenylpyridium with an extraordinary binding constant (6.24 × 10 12 M -2 ). In cisplatin-resistant MCF-7 tumor cells, the assembly induced mitochondrial aggregation substantially enhances the antitumor efficiency of cisplatin, with the ratio of apoptotic cells increasing from 43% to 96% compared to treatment with cisplatin alone, and thoroughly inhibits tumor growth in vivo . This study provides a novel way for biological phosphorescent imaging and treatment of drug-resistant cancers.

Gallbladder cancer (GBC) is the most aggressive malignancy of the biliary tract cancer, and there is a lack of effective treatment. Here, we developed a nanoparticle platform (8P4 NP) that can deliver THZ1, a cyclin-dependent kinase 7 (CDK7) inhibitor, to treat GBC. Analysis of datasets demonstrated that CDK7 was positively correlated with poor prognosis. CDK7 inhibition suppressed cell proliferation, induced apoptosis, and caused cell cycle block in GBC cells. THZ1 downregulated CDK7-mediated phosphorylation of RNA polymerase II (RNAPII), resulting in a significant downregulation of transcriptional programs, with a preferential repression of oncogenic transcription factors. To improve the tumor targeting efficiency of THZ1, 8P4 NPs were prepared and assembled with THZ1 to form THZ1@8P4 NPs. Compared with free THZ1, THZ1@8P4 NPs showed more advantages in prolonging blood circulation, escaping from lysosomes and increasing cellular uptake. Importantly, THZ1@8P4 NPs demonstrated a more significant inhibition effect on GBC cells than free THZ1 in vitro . In addition, THZ1@8P4 NPs could efficiently deliver THZ1 to tumor sites in a patient-derived xenograft model of early recurrence, leading to tumor regression and transcriptional inhibition with minimal toxicity. In summary, we conclude that THZ1@8P4 NPs provide a potent therapeutic strategy that targets CDK7-mediated transcriptional addiction in GBC.

High-sensitivity and wide-frequency attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is highly demanded in unraveling electrocatalytic processes at the molecular level. In this work, an in situ ATR-SEIRAS technique incorporating a micromachined Si wafer window, p -polarized infrared radiation, and isotope labeling is extended to revisit the acetaldehyde oxidation reaction (AOR) on a Pt electrode in an acidic medium. New spectral features in the fingerprint region are detected, including ω(C-H) at 1078 cm -1 and ν as (C-C-O) at 919 cm -1 for adsorbed acetaldehyde and δ(O-C-O) at 689 cm -1 for adsorbed acetate, besides the other enhanced and clearly discriminated spectral signals at higher frequencies. Time-evolved and potential-dependent ATR-SEIRAS measurements together with advanced density functional theory calculations considering the coadsorption of CO and C 2 species enable clarification of the structures and roles of surface C 2 intermediates (η 1 (C)-acetyl and η 1 (H)-acetaldehyde), as reflected by the two bands at 1630 and 1663 cm -1 , respectively, leading to updated pathways for the AOR on a Pt electrode.

A novel triazolyl bridged cucurbituril (CB)-cyclodextrin (CD) dimer was synthesized via click reaction of monopropargyl modified octamethylcucurbit[6]uril and mono-6-azido-β-cyclodextrin. Moreover, it could form stable supramolecular inclusion complexes possessing efficient fluorescence resonance energy transfer, which benefited from the fact that CD and CB can bind amantadine- and pyridinium-containing fluorophores simultaneously. The supramolecular inclusion complex behaviors were investigated by NMR spectroscopy, UV-vis absorption, and fluorescence spectroscopy.

Tumor metastasis is the most dangerous stage in tumorigenesis and its evolution, which causes about 80% clinical death. However, common therapies including chemotherapy may increase the risk of tumor metastasis while killing cancer cells. Tumor metastasis is closely related to many factors in the tumor microenvironment, especially hypoxia. As one of the characteristics of a malignant tumor microenvironment, hypoxia plays an important role in the growth, metabolism, and metastasis of tumors. Upregulation of the hypoxia-inducible factor (HIF) would stimulate the metastasis and migration of cancer cells. In this study, we developed an artificial oxygen carrier system, a hemoglobin-loaded liposome (Hb@lipo), which was capable of effectively delivering oxygen to tumor. The way of providing oxygen not only alleviated tumor hypoxia but also downregulated the expression of HIF, which is conducive to reducing tumor malignancy. Alleviating the tumor hypoxic microenvironment alone is not enough to inhibit tumor metastasis; thus, we prepared the liposome containing a chemotherapeutic agent cabazitaxel (CBZ@lipo). Our data indicated that the combination therapy of Hb@lipo and CBZ@lipo can efficiently kill cancer cells and inhibit tumor growth. At the same time, it can effectively entrap cancer cells in tumor sites by relieving the hypoxic microenvironment of tumors and reduce the metastasis of cancer cells during and after the chemotherapy. Our research may provide a clinical cancer chemotherapy reference that reduces the risk of cancer cell metastasis while inhibiting tumor growth.

This letter reports on a novel cost-efficient and multifunctional barcode-like sensors array (BLSA) printed with a conductive bioinspired smart ink. The conductive  ink (P@G ink), which can be further chemically engineered with different organic ligands, was generated via facile one-pot hydrothermal reduction of graphene oxide (GO) in dopamine (DA) as coreductan Usingvarious  chemical derivatives of the P@G inks on a flexible substrate (e.g., Kapton), a highly integrated BLSA as well as smart nose/tongue mimic array were generated for simultaneous sensing and distinguishing of complex physical and chemical stimuli, including temperature, light, air pressure, relative humidity, and volatile organic compounds (VOCs). Due to these very attractive features, the reported P@G ink-based BLSA would have the potential for unique opportunities regarding "all-in-one"-yet cost-effective-disposable electronics and sensors.

The aim of this study was to design a click-crosslinked hyaluronic acid (HA) (Cx-HA) depot via a click crosslinking reaction between tetrazine-modified HA and trans -cyclooctene-modified HA for direct intra-articular injection into joints affected by rheumatoid arthritis (RA). The Cx-HA depot had significantly more hydrogel-like features and a longer in vivo residence time than the HA depot. Methotrexate (MTX)-loaded Cx-HA (MTX-Cx-HA)-easily prepared as an injectable formulation-quickly formed an MTX-Cx-HA depot that persisted at the injection site for an extended period. In vivo MTX biodistribution in MTX-Cx-HA depots showed that a high concentration of MTX persisted at the intra-articular injection site for an extended period, with little distribution of MTX to normal tissues. In contrast, direct intra-articular injection of MTX alone or MTX-HA resulted in rapid clearance from the injection site. After intra-articular injection of MTX-Cx-HA into rats with RA, we noted the most significant RA reversal, measured by an articular index score, increased cartilage thickness, extensive generation of chondrocytes and glycosaminoglycan deposits, extensive new bone formation in the RA region, and suppression of tumor necrosis factor-α or interleukin-6 expression. Therefore, MTX-Cx-HA injected intra-articularly persists at the joint site in therapeutic MTX concentrations for an extended period, thus increasing the duration of RA treatment, resulting in an improved relief of RA.

Dual-mode optical assays are becoming more popular and attractive because they would provide robust detailed information in biochemical analysis. We herein unveil a novel dual-mode optical (i.e., UV-vis absorption and fluorescence) method for multifunctional sensing of phosphate compounds (PCs) (e.g., nucleotides and pyrophosphate) based on pattern recognition, which innovatively employs only one kind of porphyrin/lanthanide-doped upconversion nanoparticles (Ln-UCNPs) hybrid integrated with a facile pH-regulated strategy as the sensor array. An easy-to-obtain porphyrin hydrate (tetraphenylporphyrin tetrasulfonic acid hydrate, TPPS) can assemble onto the ligand-free Ln-UCNPs to construct the organic/inorganic hybrid (TPPS/Ln-UCNPs), leading to a new absorption band to quench the upconversion fluorescence of Ln-UCNPs due to fluorescence resonance energy transfer (FRET). The dual-mode optical performances of TPPS/Ln-UCNPs are characteristically correlated with the pH in aqueous solution. Thus, as a proof-of-concept design, three types of TPPS/Ln-UCNPs (TPPS/Ln-UCNPs 4 , TPPS/Ln-UCNPs 4.5 , and TPPS/Ln-UCNPs 5 ) were prepared by using buffers with different pH (at 4, 4.5, and 5) to form our proposed sensor array, which would result in individual dual-mode optical response patterns upon being challenged with PCs for their pattern recognition through a competitive mechanism between TPPS and PCs. The results show that three TPPS/Ln-UCNPs n sensors can successfully permit the sensitive detection of 14 PCs and differentiate them between different concentrations, as well as a mixture of them. The pH-dependent TPPS/Ln-UCNPs promises the simple, yet powerful discrimination of PCs via pattern recognition, would prospectively stimulate and expand the use of organic/inorganic hybrid toward more biosensing applications.

This study developed flexible light-emitting diodes (LEDs) with warm white and neutral white light. A simple ultraviolet flip-chip sticking process was adopted for the pumping source and combined with polymer and quantum dot (QD) films technology to yield white light. The polymer-blended flexible LEDs exhibited higher luminous efficiency than the QD-blended flexible LEDs. Moreover, the polymer-blended LEDs achieved excellent color-rendering index (CRI) values (Ra = 96 and R9 = 96), with high reliability, demonstrating high suitability for special applications like accent, down, or retrofit lights in the future. In places such as a museum, kitchen, or surgery room, its high R9 and high CRI characteristics can provide high-quality services.

Self-assembled growth of SrTi 0.87 Fe 0.13 O 3-δ (STF)/ZnO vertical nanocomposite films by combinatorial pulsed laser deposition is described. The nanocomposite films form vertically aligned columnar epitaxial nanostructures on SrTiO 3 substrates, in which the STF shows room-temperature magnetism. The magnetic properties are discussed in terms of strain states, oxygen vacancies, and microstructures. The nanocomposites exhibit magneto-photoluminescent coupling behavior that the near-band-edge emission of ZnO is shifted as a function of magnetic field.

Ferromagnetic Sr(GaxTiyFe0.34-0.40)O3-δ (0.1 ≤ x, y ≤ 0.5) films with single-crystal perovskite structure were epitaxially grown on (001) (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates by combinatorial pulsed laser deposition (CPLD) and compared with previous results from films grown from single targets. In CPLD films the Fe was present as both Fe(2+) and Fe(3+). The distribution of Sr, Ga, Ti, and O was homogeneous, but Fe-rich nanowires with diameter of 3 nm were present perpendicular to the film plane. The unit cell was tetragonally distorted with the ratio of out-of-plane to in-plane lattice parameter decreasing from 1.06 to 1.02 as the Ga content increased. The magnetic easy axis of the films changed from out-of-plane when Ti content y > 0.3 to isotropic as the Ga content increased, consistent with a reduction in magnetoelastic anisotropy. The Ga lowered the Faraday rotation and the magnetization but increased the optical transmittance.

A process route to fabricate templated BiFeO3/CoFe2O4 (BFO/CFO) vertical nanocomposites is presented in which the self-assembly of the BFO/CFO is guided using a self-assembled triblock terpolymer. A linear triblock terpolymer was selected instead of a diblock copolymer in order to produce a square-symmetry template, which had a period of 44 nm. The triblock terpolymer pattern was transferred to a (001) Nb:SrTiO3 substrate to produce pits that formed preferential sites for the nucleation of CFO crystals, in contrast to the BFO, which wetted the flat regions of the substrate. The crystallographic orientation and magnetic properties of the templated BFO/CFO were characterized.

Highly substituted polycyclic aromatic and heteroaromatic compounds are produced via a two-stage tandem benzannulation/cyclization strategy. The initial benzannulation step proceeds via a pericyclic cascade mechanism triggered by thermal or photochemical Wolff rearrangement of a diazo ketone. The photochemical process can be performed using a continuous flow reactor which facilitates carrying out reactions on a large scale and minimizes the time required for photolysis. Carbomethoxy ynamides as well as more ketenophilic bis-silyl ynamines and N-sulfonyl and N-phosphoryl ynamides serve as the reaction partner in the benzannulation step. In the second stage of the strategy, RCM generates benzofused nitrogen heterocycles, and various heterocyclization processes furnish highly substituted and polycyclic indoles of types that were not available by using the previous cyclobutenone-based version of the tandem strategy.

A two-stage "tandem strategy" for the synthesis of benzofused nitrogen heterocycles is described that is particularly useful for the construction of systems with a high level of substitution on the benzenoid ring. The first stage in the strategy involves a benzannulation based on the reaction of cyclobutenones with ynamides. This cascade process proceeds via a sequence of four pericyclic reactions and furnishes a multiply substituted aniline derivative which can bear a variety of functionalized substituents at the position ortho to the nitrogen. In the second stage of the tandem strategy, ring-closing metathesis generates the nitrogen heterocyclic ring. This two-step sequence provides efficient access to highly substituted dihydroquinolines, benzazepines, benzazocines, and related benzofused nitrogen heterocyclic systems. The application of this chemistry in a concise formal total synthesis of the anticancer agents (+)-FR900482 and (+)-FR66979 is described.

Ethenol is a recently identified combustion intermediate. However, its chemistry remains unclear. In present work, the removal reactions of ethenol by H atom are investigated. The geometries of all species involved in the reaction are optimized at B3LYP/6-311++G(d,p), and their single point energies are extrapolated to the infinite-basis-set limit at the level CCSD(T). Energies are also calculated at G3B3, CBS-APNO, and CCSD(T)/6-311++G(3df, 2p) for comparison. A total of six elementary reactions, including four abstractions and two additions, with explicit transition states are investigated. The results show that the reactions are selective: for abstractions, the hydrogen atom, linked to the oxygen atom, is the most reactive; while for additions, the preferred carbon site is the head "CH(2)═". The rate constants are estimated in the temperature range 300-3000 K according to the conventional transition state theory with the Eckart tunneling model. The dominant channels are the two additions in the whole temperature range. The abstractions can be competitive at high temperature but still do not dominate. The calculated rate constants for the reverse reaction of (R6), syn-CH(2)═CHOH + H ↔ CH(3)·CHOH, are consistent with the available literature values. Finally, the Fukui functions are calculated to analyze the site reactivity.

Supercritical carbon dioxide can be employed as an environmentally friendly alternative to conventional organic solvents for the synthesis of a variety of carboxylic amides. The addition of amines to ketenes generated in situ via the retro-ene reaction of alkynyl ethers provides amides in good yield, in many cases with ethylene or isobutylene as the only byproducts of the reaction. Reactions with ethoxy alkynes are performed at 120-130 degrees C, whereas tert-butoxy derivatives undergo the retro-ene reaction at 90 degrees C. With the exception of primary, unbranched amines, potential side reactions involving addition of the amines to carbon dioxide are not competitive with the desired C-N bond-forming reaction. The amide synthesis is applicable to the preparation of beta-hydroxy and beta-amino amide derivatives, as well as amides bearing isolated carbon-carbon double bonds. Preliminary experiments aimed at developing an intramolecular variant of this process to afford macrolactams suggest that the application of CO(2)/co-solvent mixtures may offer advantages for the synthesis of large-ring compounds.

In a series of poly[di(alkyl) vinylterephthalates] (PDAVTs) synthesized via radical polymerization, fine-tuning the size and shape of the side groups manipulated the supramolecular self-assembly and led to control over the formations between amorphous and 2D ordered hexagonal phases. To introduce the 2D long-range ordered structure, the size of the ester side groups at the 2- and 5-positions of the phenyl rings laterally attached to the backbones had to be in the range of propyl/isopropyl to hexyl. The relatively extended backbones observed in these polymers were attributed to steric effects from the side groups. When the n-alkyl groups were larger than hexyl, the ability to form the liquid crystalline phase gradually decreased. A completely disordered phase could be observed by substituting dodecyl groups as side groups.

An efficient palladium-catalyzed amination of aromatic bromides with hindered N-alkyl-substituted anilines is described, either using the combination of Pd(OAc)(2) and P(t-Bu)(3) or a palladium(I) tri-tert-butylphosphine bromide dimer, [Pd(mu-Br)(t-Bu(3)P)](2), a new, commercially available, and easily handled catalyst.