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A new palladium‐based catalyst system modified with dibenzofuran (DBF) was developed for acetylene hydrochlorination. The optimal Pd‐DBF/SAC catalyst with the 0.5 wt% Pd loading and the 15 wt% DBF loading exhibits an elevated performance of 99.9% acetylene conversion and 99.9% vinyl chloride selectivity for more than 400 h. Characterization analysis and density functional theory (DFT) simulations revealed that the presence of oxygen‐containing DBF species of the Pd‐DBF/SAC catalyst prevents the reduction and loss of Pd species, inhibits the carbon deposition and enhances the HCl adsorbability, resulting in superior catalytic activity and stability for acetylene hydrochlorination. [ABSTRACT FROM AUTHOR]

Polycyclic heterocycles are the most common and critical structural motifs found in a variety of natural products, medicines, fertilizers, and advanced materials. Because of their widespread use in biologically active compounds and material chemistry, functionalised dibenzo heterocyclic compounds, especially dibenzofuran, dibenzothiophene, and carbazole derivatives, garnered much attention over time. Scientists are especially interested in elucidating more efficient techniques for developing these industrially essential compounds. Dibenzo‐fused heterocycles can rapidly be synthesised using highly efficient transition metal‐catalysed strategies as well as by economic metal‐free reaction conditions. This review includes a detailed overview of the most recent significant synthetic techniques, both metal‐catalysed and metal‐free, to produce these industrially significant and medicinally important dibenzo‐fused heterocycles. [ABSTRACT FROM AUTHOR]

The π-conjugated system and the steric configuration of hole transport materials (HTMs) could greatly affect their various properties and the corresponding perovskite solar cells' efficiencies. Here, a molecular engineering strategy of incorporating different amounts of p-methoxyaniline-substituted dibenzofurans as π bridge into HTMs was proposed to develop oligomer HTMs, named mDBF, bDBF, and tDBF. Upon extending the π-conjugation of HTMs, their HOMO energy levels were slightly deepened, significantly increasing the thermal stability and hole mobility. The incorporation of p-methoxyaniline bridges built one or two additional triphenylamine propeller structures, resulting in a denser film. Here, the tDBF-based n-i-p flexible perovskite solar cells createdchampion efficiency, giving a power conversion efficiency of 19.46%. And the simple synthesis and purification process of tDBF contributed to its low manufacturing cost in the laboratory. This work provided a reference for the development of low-cost and efficient HTMs. [ABSTRACT FROM AUTHOR]

Abstract Bioactive compounds from the wood-decay fungus Xylaria cf. longipes SWUF08-81, cultivated in three different culture media (GM, YM and PDB), were isolated. Their structures and stereochemistry were deduced from spectroscopic and MS data analysis, together with quantum chemical calculations of 13C NMR chemical shifts and electronic circular dichroism (ECD) spectra. Five undescribed polyketides including dibenzofuran (1), mellein (2), dihydroisocoumarin (15), and two pyrans (16, 17), together with twenty-three compounds were determined. Compounds 18 and 20 were significantly toxic against cancer cell lines (HCT116, HT29, MCF-7 and HeLa) based on the MTT assay. Quantification by HPLC showed that 18 was produced three-fold higher in the broth of PDB than YM. These studies showed that the production of different compounds were primarily dependent on nutrition sources and it has given a starting point for the growth optimization conditions for the scaling up of bioactive compounds production. Graphical Abstract

Bioactive compounds from the wood-decay fungus Xylaria cf. longipes SWUF08-81, cultivated in three different culture media (GM, YM and PDB), were isolated. Their structures and stereochemistry were deduced from spectroscopic and MS data analysis, together with quantum chemical calculations of 13C NMR chemical shifts and electronic circular dichroism (ECD) spectra. Five undescribed polyketides including dibenzofuran (1), mellein (2), dihydroisocoumarin (15), and two pyrans (16, 17), together with twenty-three compounds were determined. Compounds 18 and 20 were significantly toxic against cancer cell lines (HCT116, HT29, MCF-7 and HeLa) based on the MTT assay. Quantification by HPLC showed that 18 was produced three-fold higher in the broth of PDB than YM. These studies showed that the production of different compounds were primarily dependent on nutrition sources and it has given a starting point for the growth optimization conditions for the scaling up of bioactive compounds production. [ABSTRACT FROM AUTHOR]

Ô nhiễm các hợp chất hydrocarbon thơm đa vòng gây ra do dư lượng chất độc chiến tranh hoặc từ chất thải của các hoạt động công nghiệp đã để lại nhiều hậu quả nghiêm trọng cho sức khỏe con người và môi trường sinh thái. Phương pháp phục hồi sinh học sử dụng các vi sinh vật có khả năng phân hủy các hợp chất ô nhiễm cho thấy hiệu quả xử lý cao, chi phí thấp, bền vững và thân thiện với môi trường hơn so với các phương pháp lý hóa thông thường. Trong nghiên cứu này, chủng vi khuẩn Paenibacillus naphthalenovorans 4B1, phân lập từ đất nhiễm dioxin, được nghiên cứu tối ưu hóa các điều kiện nuôi cấy và đánh giá khả năng phân hủy các hợp chất dibenzofuran và naphthalene. Kết quả nghiên cứu cho thấy chủng vi khuẩn này sinh trưởng tốt nhất trên môi trường muối khoáng bổ sung 1250 mg/L dibenzofuran hoặc 750 mg/L naphthalene, pH 7,0, nuôi cấy ở nhiệt độ 45°C và tốc độ khuấy trộn 180 vòng/phút với mật độ tế bào lần lượt là 9,42 × 107 và 5,6 × 107 CFU/mL. Phân tích sắc ký khí hàm lượng cơ chất còn lại trong môi trường nuôi cấy cho thấy chủng 4B1 có khả năng phân hủy dibenzofuran và naphthalene với hiệu suất lần lượt là 79,76% và 83,03% sau 72 giờ nuôi cấy. Kết quả này là cơ sở cho việc ứng dụng chủng vi khuẩn Paenibacillus naphthalenovorans 4B1 trong nghiên cứu xử lý các môi trường bị ô nhiễm các hợp chất hydrocarbon thơm đa vòng.

Dibenzofuran and its derivatives are ubiquitous and important medicinal and natural products. Many contain electron‐rich aryl rings. Forming the key intramolecular Ar−Ar bond using traditional cross‐coupling is difficult. The C−H functionalisation (C−H activation) approach is, in principle, far more useful. However, we previously found that the well‐established conditions, which promote C−H functionalisation through Concerted Metalation‐Deprotonation (CMD), proved unsatisfactory. Herein, we report a Pd‐catalysed C−H functionalisation protocol that works with electron‐rich arenes. We use tetrabutylammonium acetate (NBu4OAc), which we suspect can act as base, ligand and solvent, rendering this protocol a simple and efficient route to electron‐rich dibenzofurans. [ABSTRACT FROM AUTHOR]

The high content of heteroatomic oxygen in medium-low temperature coal tar can cause the problems of low calorific value and poor oil stability. Hydrodeoxygenation is one of the most effective methods for coal tar hydrodeoxygenation. Ni/CeϑM1-ϑOx catalysts (M = Fe, Ga, Zr) doped with metal ions of CeO2 were prepared by hydrothermal method. The effect of the relative content of oxygen vacancies of catalysts on hydrodeoxygenation of the dibenzofuran was studied. The morphology and structure of catalysts were characterized by transmission electron microscope (TEM) and X-ray diffraction (XRD), and the oxygen vacancies on the catalyst surface were studied by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The hydrodeoxygenation performance of dibenzofuran of Ni/CeϑM1-ϑOx catalysts with different amounts of oxygen vacancies was evaluated in a high-pressure reactor. The results show that after doping Ga, Zr and Fe with CeO2, Ga, Zr and Fe enter the CeO2 lattice to form a solid solution structure, which leads to the distortion of CeO2 lattice and promotes the formation of oxygen vacancies. Ni/CeϑM1-ϑOx catalysts have the highest relative content of oxygen vacancies and the highest deoxygenation activity. After reaction for 180 min, the selectivity of oxygen-containing intermediates on Ni/CeϑM1-ϑOx catalysts reduces to 40.03% and the selectivity of deoxygenation products increases to 59.81%, indicating that the relative content of oxygen vacancies of catalysts improves their activity. [ABSTRACT FROM AUTHOR]

Solid–liquid equilibria (SLE) of binary mixtures of several n-alkanes (n-octadecane, n-eicosane, n-tetracosane, n-pentacosane, n-triacontane) and dibenzofuran covering the whole composition range were measured by differential scanning calorimetry (DSC) in a temperature range of 301–356 K. The dibenzofuran and the n-alkanes are completely miscible in the liquid state but non-miscible in the solid state, and in the context of this work, they seem to exhibit eutectic behavior. A linear trend is obtained for the eutectic temperature and eutectic composition versus the number of carbon atoms of n-alkane. The experimental data were compared to predictions made by using the ideal solution model, the DISQUAC model and several versions of the UNIFAC model, including the classical UNIFAC, the modified versions of Lyngby and Dortmund, and the recently proposed modified UNIFAC (NIST) model, to account for non-ideality in the liquid phase. Moreover, the experimental data were also compared with COSMO-RS predictions that utilize quantum chemical calculations and statistical thermodynamics to interpret the behavior of molecular interactions in the binary mixture. A good agreement was obtained between the predicted and the experimental temperatures. [ABSTRACT FROM AUTHOR]

The contamination of the environment has been a global issue, and bioremediation is proposed as an option to clean up the contamination sites with the promising utilization of bacterial community capabilities. The indigenous bacterial community in the landfill leachate is recognized to carry enzymes for the degradation of contaminants such as dioxin congeners, the dibenzofuran. Environmental factors have been known to influence the process to achieve successful biodegradation, and the optimized conditions may speed up the biodegradation process. Thus, this study was conducted to optimize the substrate availability, temperature, and pH factor for the degradation of dibenzofuran from landfill leachate by the native bacterial community in landfill leachate. This study uses the onefactor at-time (OFAT) approach to measure dibenzofuran degradation. The landfill leachate with enrichment of dibenzofuran (15 to 45 mg L-1) was incubated at temperatures (30°C to 42°C) and pH (5 to 9) for 24 hours before being extracted and analyzed. From the first part of the study, 15 mg L-1 of dibenzofuran, 30°C temperature, and pH 7 have shown the highest dibenzofuran degradation. Later, the optimum condition of dibenzofuran removal (74.40%) was achieved when the landfill leachate was spiked with 15 ppm dibenzofuran at 30°C and pH 7 for 24 hours. This study proposes optimized conditions that give a better result for dibenzofuran degradation, which may enhance bioremediation. [ABSTRACT FROM AUTHOR]

The π-conjugated system and the steric configuration of hole transport materials (HTMs) could greatly affect their various properties and the corresponding perovskite solar cells’ efficiencies. Here, a molecular engineering strategy of incorporating different amounts of p-methoxyaniline-substituted dibenzofurans as π bridge into HTMs was proposed to develop oligomer HTMs, named mDBF, bDBF, and tDBF. Upon extending the π-conjugation of HTMs, their HOMO energy levels were slightly deepened, significantly increasing the thermal stability and hole mobility. The incorporation of p-methoxyaniline bridges built one or two additional triphenylamine propeller structures, resulting in a denser film. Here, the tDBF-based n-i-p flexible perovskite solar cells createdchampion efficiency, giving a power conversion efficiency of 19.46%. And the simple synthesis and purification process of tDBF contributed to its low manufacturing cost in the laboratory. This work provided a reference for the development of low-cost and efficient HTMs.

This research shows the development of a miniaturized solid-phase extraction method with UV-Vis detection for simultaneous determination of dibenzofuran, fluoranthene and phenanthrene using chemometrics approaches. After synthesis of Fe3O4 nanoparticles (Fe3O4 NPs), the surface of the nanoparticles was modified by Triton X100 coating. The influence of extraction solvent and volume, concentration of Triton X100, extraction time, and sample pH were studied and optimized. Due to high spectral overlapping, resolving ternary mixtures for simultaneous determination of targets with classical analytical methods is impossible. Therefore, the recorded UV-Vis spectra were transformed using continuous wavelet transform and then subjected to artificial neural networks (ANNs). The Db4 mother wavelet was used as the better mother wavelet. For simultaneous detection of analytes, a comparison of feed-forward back-propagation and radial basis function networks was accomplished. The calibration graphs showed linearity in the ranges of 2.4–250 ng mL−1, 50–3750 ng mL−1, and 48–5000 ng mL−1 with a limit of detection of 0.58, 9.5 ng mL−1, and 12.5 ng mL−1 under optimal conditions for phenanthrene, fluoranthene, and dibenzofuran, respectively. The limit of quantitation was achieved at 3.52 ng mL−1, 16.35 ng mL−1, and 31.3 ng mL−1 for phenanthrene, fluoranthene and dibenzofuran, respectively. The method involving TX-100-coated Fe3O4 NPs in a liquid sample phase for analyte extraction, followed by ethanol desorption and UV-Vis detection, was successfully applied for the determination of polycyclic aromatic hydrocarbons in oil-field water and algae samples. [ABSTRACT FROM AUTHOR]

Condensation of dibenzofuran based tripyrrane with dipyrroethene diol under acid catalyzed porphyrin forming conditions resulted in the formation of dibenzofuran embedded calix pentaphyrins with two meso‐sp3 carbons instead of expected fully conjugated dibenzofuran (DBF) embedded pentaphyrins. Three examples of DBF embedded calix pentaphyrins have been synthesized by adopting the [3+2] condensation methodology and characterized by various spectroscopic and theoretical methods. The NMR studies that include COSY, NOESY, HMBC and HSQC clearly confirmed the molecular structures of DBF embedded bis‐(calix)‐pentaphyrins. The optimized structures showed that the DBF embedded bis‐(calix)‐pentaphyrin macrocycles adopted figure eight conformation due to presence of two sp3 carbon atoms (C1 and C22) at meso positions which obstructed the conjugation throughout the macrocycle. The absorption spectra of macrocycles showed non‐aromatic features with a sharp strong band at 480 nm and a broad band in the region of 600–800 nm which were significantly red shifted with distinct colour change in protonated derivatives of DBF embedded bis‐(calix)‐pentaphyrins. [ABSTRACT FROM AUTHOR]

Dibenzo-fused five-membered heteroaromatic compounds, including dibenzofuran, carbazole, and dibenzothiophene, are fundamental structural units in various important polycyclic heteroaromatic compounds. The intramolecular C-H/C-H biaryl coupling of diaryl (thio)ethers and amines based on palladium(II) catalysis under oxidative conditions is known to be one of the most effective, step-economic methods for their construction. Representative examples for the construction of structurally intriguing π-extended polycyclic heteroaromatics through catalytic coupling reactions are briefly summarized in this mini-review. [ABSTRACT FROM AUTHOR]

In this study, the photophysical characteristics and electroluminescence of three green Ir(III) complexes with newly created cycloalkyl fused dibenzofuran ligands are examined. The results demonstrate that the cycloalkyl fused dibenzofuran ligand can modify the intermolecular interactions and alter the horizontal emitting dipole orientation ratios of dopants in phosphorescent organic light‐emitting diodes (PhOLEDs). One of the three phosphors, Ir(TBF)2(mppy), shows high photoluminescence quantum yield of 0.96 and a high horizontal emitting dipole orientation ratio of 0.80. Therefore, an optimized PhOLED using Ir(TBF)2(mppy) exhibits a peak external quantum efficiency (EQE) of 27.1% and a very small efficiency roll‐off with a high EQE of 25.1% at 10 000 cd m−2. It is significant that the high EQE device maintains the CIE chromaticity coordinates over a wide doping concentration range (3–10 wt%), thus creating new possibilities for the dopant design strategy for the practical use of PhOLEDs. [ABSTRACT FROM AUTHOR]

Abstract Background Sphingomonas wittichii RW1 is one out of three strains capable of metabolizing dioxin as a sole source for carbon and energy. Under laboratory conditions the degradation rates for these aromatics are relatively high (5 and 8 h for dibenzofuran (DBF) and dibenzo-p-dioxin (DD), respectively). However, their degradation rates are much lower in the environment due to several factors. One of these factors is the availability of other carbon sources. Acetate is a metabolized carbon source by S. wittichii RW1 and its presence in the environment would have a negative impact on DBF and DD degradation. In addition, expression of most of the genes for DBF and DD degradation were downregulated when grown on acetate compared to their growth on DBF and DD. We hypothesized that blocking the acetate utilization pathway in S. wittichii RW1 would prevent it from using acetate when present along with DD and DBF in contaminated sites. Results Blocking the glyoxylate shunt by deleting isocitrate lyase gene (icl) prevented the mutant strain (RW1Δicl) from using acetate as a sole carbon source thus depending on available DBF and DD in polluted sites. Our results showed that deletion of icl did not affect growth of S. wittichii RW1 on DBF and DD but blocked it from growing on acetate. Conclusion Our results introduces an engineered strain that can be used as a new candidate to clean dioxin-contaminated sites which are rich with acetate.

The cardo structure and long side chain of poly(isatin biphenyl) are conducive to the motion and aggregation of cations over mainchain type membranes, therefore it is used as the pristine membrane. It is well known that random copolymerization and branching can effectively modify the configuration and properties of polymers. Herein, we use random copolymerization and branching to improve the behaviors of poly(isatin biphenyl) anion exchange membranes (AEMs). High-curvature random copolymers (QPIDBP-n) and high free volume branched polymers (b-QPIBP-x) are synthesized via polycondensation. The random copolymerization results in the formation of a twisted chain structure, while the introduction of branching agent leads to the formation of orderly stacking of chains. Both of these approaches have been demonstrated to boost the microphase-separated morphology of the pristine polymer. A series of QPIDBP-n and b-QPIBP-x are tested and an optimal ratio is explored. QPIDBP-40 and b-QPIBP-5 exhibit high overall performance. Among the as-prepared membranes, b-QPIBP-5 exhibits the highest conductivity (80 °C, 160.7 mS cm−1) with a swelling ratio of 20.7 %. The residual conductivity of b-QPIBP-5 is 93.1 % after the 1200 h alkali stability test. The cell assembled by b-QPIBP-5 achieves a peak power density of 680 mW cm−2. Moreover, the b-QPIBP-5 based cell holds 88.6 % voltage after the in-situ stability test for 50 h. [Display omitted] • Random copolymerization and branching are used to improve the properties. • A series of random copolymers and branched polymers are synthesized. • QPIDBP-40 and b-QPIBP-5 exhibit high conductivity and good alkali stability. [ABSTRACT FROM AUTHOR]

The soil is a rich ecosystem where many ecological interactions are mediated by small molecules, and in which amoebae are low-level predators and also prey. The social amoeba Dictyostelium discoideum has a high genomic potential for producing polyketides to mediate its ecological interactions, including the unique 'Steely' enzymes, consisting of a fusion between a fatty acid synthase and a chalcone synthase. We report here that D. discoideum further increases its polyketide potential by using the StlB Steely enzyme, and a downstream chlorinating enzyme, to make both a chlorinated signal molecule, DIF-1, during its multi-cellular development, and a set of abundant polyketides in terminally differentiated stalk cells. We identify one of these as a chlorinated dibenzofuran with potent anti-bacterial activity. To do this, StlB switches expression from prespore to stalk cells in late development and is cleaved to release the chalcone synthase domain. Expression of this domain alone in StlB null cells allows synthesis of the stalk-associated, chlorinated polyketides. Thus, by altered expression and processing of StlB, cells make first a signal molecule, and then abundant secondary metabolites, which we speculate help to protect the mature spores from bacterial infection. [ABSTRACT FROM AUTHOR]

Parrotia subaequalis, an endangered Tertiary relict tree native to China and a member of the Hamamelidaceae family, is one of several host plant species in this family that exhibit unique ecological habits, such as gall formation. Tree galls are the results of complex interactions between gall-inducing insects and their host plant organs. The formation of galls may serve to protect other regions of the plant from potential damage, often through the production of phytoalexins. In this study, a preliminary investigation was carried out on the metabolites of the 90% MeOH extract derived from the closed spherical galls on the twigs of P. subaequalis. Consequently, nine previously undescribed benzofuran-type and dibenzofuran-type phytoalexins (parrotiagallols A-I, 1-9, respectively) were isolated and characterized, along with several known miscellaneous metabolites (10-17). Their chemical structures and absolute configurations were elucidated using spectroscopic methods, a combination of calculated and experimental electronic circular dichroism data, and single crystal X-ray diffraction analyses. Among these compounds, 1 and 2 are identified as neolignan derivatives, while compounds 3-5 are classified as 9,10-dinorneolignans. Compound 6 represents a rare 2,3-seco-neolignan, and compounds 7-9 are dihydroxy-dimethyl-dibenzofuran derivatives. Parrotiagallol A (1) showed considerable antibacterial activity against Staphylococcus aureus, with an MIC value of 14 μM. Additionally, parrotiagallol E (5) and methyl gallate (17) exhibited inhibitory effects against ATP-citrate lyase (ACL), a potential therapeutic target for hyperlipidemia, with IC 50 values of 5.1 and 9.8 μM, respectively. The findings underscore that galls not only serve as physical defense barriers but also benefit from the chemical defense system of the host plants. These insights provide avenues for exploring potential new therapeutic agents for S. aureus infections and ACL-related diseases, while also promoting scientific conservation strategies for P. subaequalis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Among various matrix metalloproteinases (MMPs), MMP-12 is one of the potential targets for cancer and other diseases. However, none of the MMP-12 inhibitors has passed the clinical trials to date. Therefore, designing potential MMP-12 inhibitors as new drug molecules can provide effective therapeutic strategies for several diseases. In this study, a series of dibenzofuran and dibenzothiophene derivatives were subjected to different 2D and 3D-QSAR techniques to point out the crucial structural contributions highly influential toward the MMP-12 inhibitory activity. These techniques identified some structural attributes of these compounds that are responsible for influencing their MMP-12 inhibition. The carboxylic group may enhance proper binding with catalytic Zn 2+ ion at the MMP-12 active site. Again, the i -propyl sulfonamido carboxylic acid function contributed positively toward MMP-12 inhibition. Moreover, the dibenzofuran moiety conferred stable binding at the S1' pocket for higher MMP-12 inhibition. The steric and hydrophobic groups were found favourable near the furan ring substituted at the dibenzofuran moiety. Besides these ligand-based approaches, molecular docking and molecular dynamic (MD) simulation studies not only elucidated the importance of several aspects of these MMP-12 inhibitors while disclosing the significance of the finding of these QSAR studies and their influences toward MMP-12 inhibition. The MD simulation study also revealed stable and compact binding between such compounds at the MMP-12 active site. Therefore, the findings of these validated ligand-based and structure-based molecular modeling studies can aid the development of selective and potent lead molecules that can be used for the treatment of MMP-12-associated diseases.Communicated by Ramaswamy H. Sarma.

Solid–liquid equilibria for binary mixtures formed by biphenyl and n-tetracosane and ternary mixtures formed by n-tetracosane + dibenzofuran + biphenyl were experimentally determined using differential scanning calorimetry (DSC). The liquidus lines were established from the onset temperatures of the melting peaks observed in the thermograms. The experimental data were compared to predictions made by a thermodynamic model considering ideal solution. Non idealities were also computed by means of the group contribution method UNIFAC. Original UNIFAC and several modifications such as UNIFAC-Lyngby and UNIFAC-Dortmund versions were assessed. The polymorphism phenomenon was considered and the heat capacity contribution was supposed to be negligible since the involved compound have nearby melting points. The best description is obtained with UNIFAC-Lyngby method, which leads to the lowest deviations in melting temperature and activity coefficients. This work contributes to acquire knowledge about solid–liquid phase behavior of multi-components systems containing heavy n-alkanes and aromatics, which is scarce in literature. [ABSTRACT FROM AUTHOR]

Two new compounds, comprising one dibenzofuran, named usneaceratin A (1), and one phenolic acid, named usneaceratin B (2), together with one known dibenzofuran, isousnic acid (3), and two known phenolics, orsellinic acid (4) and methyl orsellinate (5) were clarified from the lichen Usnea ceratina using variously chromatographic methods. Their structures were testified by comprehensive HR-ESI-MS, and NMR spectroscopic analysis, and comparison with published data. Their α-glucosidase inhibitory activity of all compounds was measured. Usneaceratin B (2) possessed better inhibition against α-glucosidase enzyme (IC50 value of 41.8 μM) than the standard drug acarbose (IC50 value of 214.50 μM). [ABSTRACT FROM AUTHOR]

This research shows the development of a miniaturized solid-phase extraction method with UV-Vis detection for simultaneous determination of dibenzofuran, fluoranthene and phenanthrene using chemometrics approaches. After synthesis of Fe3O4 nanoparticles (Fe3O4 NPs), the surface of the nanoparticles was modified by Triton X100 coating. The influence of extraction solvent and volume, concentration of Triton X100, extraction time, and sample pH were studied and optimized. Due to high spectral overlapping, resolving ternary mixtures for simultaneous determination of targets with classical analytical methods is impossible. Therefore, the recorded UV-Vis spectra were transformed using continuous wavelet transform and then subjected to artificial neural networks (ANNs). The Db4 mother wavelet was used as the better mother wavelet. For simultaneous detection of analytes, a comparison of feed-forward back-propagation and radial basis function networks was accomplished. The calibration graphs showed linearity in the ranges of 2.4–250 ng mL−1, 50–3750 ng mL−1, and 48–5000 ng mL−1 with a limit of detection of 0.58, 9.5 ng mL−1, and 12.5 ng mL−1 under optimal conditions for phenanthrene, fluoranthene, and dibenzofuran, respectively. The limit of quantitation was achieved at 3.52 ng mL−1, 16.35 ng mL−1, and 31.3 ng mL−1 for phenanthrene, fluoranthene and dibenzofuran, respectively. The method involving TX-100-coated Fe3O4 NPs in a liquid sample phase for analyte extraction, followed by ethanol desorption and UV-Vis detection, was successfully applied for the determination of polycyclic aromatic hydrocarbons in oil-field water and algae samples.

[Display omitted] • Two series of dibenzofuran- and dibenzothiophene-based liquid crystals were designed and synthesised respectively. • All of the obtained mesogens possessed large negative dielectric anisotropy values. • The calculated orientation of the dipole moment in these compounds was almost perpendicular to their long molecular axis. • A new negative LC mixture with excellent low-temperature stability was formulated. Two series of dibenzofuran- and dibenzothiophene-based liquid crystals were designed and synthesised respectively. The structures of the intermediates and the target mesogens were confirmed by nuclear magnetic resonance and mass spectrometry. The melting points of dibenzofuran-based liquid crystals were lower than dibenzothiophene-based ones if the 3-position was long-chain alkoxy while a reversed result was obtained when cyclohexyl and tetrahydropyran were introduced. All of the designed dibenzofuran- and dibenzothiophene-based liquid crystals possessed large negative dielectric anisotropy (Δ ε) values when compared with the reference compounds, which proved the effectiveness of these two heterocycle core units in the improvement of the negative Δ ε. The DFT calculations found that the elevation of the negative Δ ε values might be owed to the orientation of the dipole moment in these new compounds was almost perpendicular to their long molecular axis. A new liquid crystal mixture LTNLCM-1 was finally formulated, which could be stored at −20 °C (−40 °C when filled in liquid crystal cell) for two weeks without any obvious precipitation, illustrating the vital function of the dibenzothiophene-based compounds in improvement of the low-temperature stability of liquid crystal mixtures. [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduction of DBF accelerates the nucleation of perovskite and delays the crystallization process. • π-π stacked molecules (DBF) anchor the grain boundaries defects by forming adducts with the under-coordinated lead ions. • An excellent PCE of 20.18 % and improved stability were achieved for the DBF-treated devices (1.68 eV bandgap). Owing to the easy migration of halogen ions in wide-bandgap perovskite, it will lead to the formation of a large number of uncoordinated Pb2+ to form deep-level defects, which seriously affects the power conversion efficiency (PCE) and stability of wide-bandgap perovskite solar cells (PSCs). The introduction of additives has been recognized as an effective method to improve these defects, especially Lewis acid-base additives. Herein, Lewis base molecule dibenzofuran (DBF) with π-conjugated system, which can form π-π stacked dimer, is used as a perovskite additive. The detailed crystallization process of perovskite main precursor triggered by DBF is measured by using laser scanning confocal microscopy. It is demonstrated that the addition of DBF in perovskite samples resulted in a deceleration of the crystallization process, which is due to the formation of Lewis acid-base complexes between DBF π-π stacked dimer and perovskite, which can obtain perovskite films with reduced defect density. As a result, the champion PCE of the wide-bandgap (1.68 eV) perovskite device reaches 20.18 %, significantly higher than the control device (17.79 %). Additionally, the device with no encapsulation demonstrates better stability, as it maintains over 90 % of the initial PCE under an air environment with 30–40 % relative humidity (RH) and 25 °C for 1200 h. [ABSTRACT FROM AUTHOR]

Background: Sphingomonas wittichii RW1 is one out of three strains capable of metabolizing dioxin as a sole source for carbon and energy. Under laboratory conditions the degradation rates for these aromatics are relatively high (5 and 8 h for dibenzofuran (DBF) and dibenzo-p-dioxin (DD), respectively). However, their degradation rates are much lower in the environment due to several factors. One of these factors is the availability of other carbon sources. Acetate is a metabolized carbon source by S. wittichii RW1 and its presence in the environment would have a negative impact on DBF and DD degradation. In addition, expression of most of the genes for DBF and DD degradation were downregulated when grown on acetate compared to their growth on DBF and DD. We hypothesized that blocking the acetate utilization pathway in S. wittichii RW1 would prevent it from using acetate when present along with DD and DBF in contaminated sites. Results: Blocking the glyoxylate shunt by deleting isocitrate lyase gene (icl) prevented the mutant strain (RW1Δicl) from using acetate as a sole carbon source thus depending on available DBF and DD in polluted sites. Our results showed that deletion of icl did not affect growth of S. wittichii RW1 on DBF and DD but blocked it from growing on acetate. Conclusion: Our results introduces an engineered strain that can be used as a new candidate to clean dioxin-contaminated sites which are rich with acetate. [ABSTRACT FROM AUTHOR]

The phytochemical investigation of the dichloromethane/methanol (1:1) extract of the stem bark of Scyphocephalium ochocoa, led to the isolation of one new dibenzofuran derivative, named scyphocephalione A (1), along with three other compounds, including epicatechin (2), gentisic acid (3) and myo-inositol (4). The structures of all the compounds were established with help of spectroscopic data including IR, UV, MS, 1 D- and 2 D-NMR, as well as by comparison with previously reported data in literature, and chemical modification. All the compounds were obtained from the genus Scyphocephalium for the first time. The anti-inflammatory activity (using chemiluminescence technique) of the crude extract and compound 1, together with NO inhibition (using ELISA), TNF-α (using ELISA) and MCF-7 cells cytotoxicity effects (using MTT assay) of compound 1 were assessed. From the results obtained, compound 1 could be considered as a promising chemotherapeutic agent for the treatment of inflammatory diseases. [ABSTRACT FROM AUTHOR]

We mapped the entire visible range of the electromagnetic spectrum and achieved white light emission (CIE: 0.31, 0.34) by combining the intrinsic ns‐fluorescence with ultralong ms‐phosphorescence from purely organic dual emitters. We realized small molecular materials showing high photoluminescence quantum yields (ΦL) in the solid state at room temperature, achieved by active exploration of the regioisomeric substitution space. Chromophore stacking‐supported stabilization of triplet excitons with assistance from enhanced intersystem crossing channels in the crystalline state played the primary role for the ultra‐long phosphorescence. This strategy covers the entire visible spectrum, based on organic phosphorescent emitters with versatile regioisomeric substitution patterns, and provides a single molecular source of white light with long lifetime (up to 163.5 ms) for the phosphorescent component, and high overall photoluminescence quantum yields (up to ΦL=20 %). [ABSTRACT FROM AUTHOR]

Catechol 1,2-dioxygenase (CAT1) is a key enzyme for the ortho-cleavage pathway involved in the degradation of dibenzofuran, a dioxin derivative, which is a highly toxic environmental pollutant. The present study aims to investigate appropriate culture conditions for enhancing the expression of the cat1 gene encoding CAT1 enzyme from Burkholderia cepacia DF4 in Escherichia coli M15. The optimized culture conditions for gene expression are cell density at the time of induction, shaking speed, induction temperature, induction time, and inducer concentration. The highest level for CAT1 was obtained at the IPTG concentration of 1.2 mM, 10 hours after induction at 35 °C, shaking speed 200 rpm with cell density at OD600 0.7.

Dibenzo-fused five-membered heteroaromatic compounds, including dibenzofuran, carbazole, and dibenzothiophene, are fundamental structural units in various important polycyclic heteroaromatic compounds. The intramolecular C-H/C-H biaryl coupling of diaryl (thio)ethers and amines based on palladium(II) catalysis under oxidative conditions is known to be one of the most effective, step-economic methods for their construction. Representative examples for the construction of structurally intriguing π-extended polycyclic heteroaromatics through catalytic coupling reactions are briefly summarized in this mini-review.

Sphingomonas wittichii RW1 grows on the two related compounds dibenzofuran (DBF) and dibenzo-p-dioxin (DXN) as the sole source of carbon. Previous work by others (P. V. Bunz, R. Falchetto, and A. M. Cook, Biodegradation 4:171-178, 1993, https://doi/org/10.1007/BF00695119) identified two upper pathway meta cleavage product hydrolases (DxnB1 and DxnB2) active on the DBF upper pathway metabolite 2-hydroxy-6-oxo-6-(2-hydroxyphenyl)-hexa-2,4-dienoate. We took a physiological approach to determine the role of these two enzymes in the degradation of DBF and DXN by RW1. Single knockouts of either plasmid-located dxnB1 or chromosome-located dxnB2 had no effect on RW1 growth on either DBF or DXN. However, a double-knockout strain lost the ability to grow on DBF but still grew normally on DXN, demonstrating that DxnB1 and DxnB2 are the only hydrolases involved in the DBF upper pathway. Using a transcriptomicsguided approach, we identified a constitutively expressed third hydrolase encoded by the chromosomally located SWIT0910 gene. Knockout of SWIT0910 resulted in a strain that no longer grows on DXN but still grows normally on DBF. Thus, the DxnB1 and DxnB2 hydrolases function in the DBF but not the DXN catabolic pathway, and the SWIT0190 hydrolase functions in the DXN but not the DBF catabolic pathway. [ABSTRACT FROM AUTHOR]

The Passaic River in New Jersey, USA is heavily polluted by chlorodibenzo-p-dioxins (CDDs). Highly chlorinated CDDs are dechlorinated by anaerobic bacteria from these sediments, producing lightly chlorinated or even non-chlorinated dibenzo-p-dioxin (DD) daughter products. Surficial Passaic River sediments were enriched under aerobic conditions and three bacterial strains (PR1, PR2 and PR3) were isolated using dibenzofuran (DF) as a model substrate. PR1 is closely related to Janibacter terrae (99.4%), a known CDD and DD degrader. PR2 and PR3 are closely related to Agromyces mediolanus (99.2%) and Arthrobacter oryzae (99.5%), respectively, which are genera not known to degrade CDDs. Janibacter PR1 grew more rapidly on DF than PR2 and PR3. The less well characterized PR2 and PR3 both degraded DD and 2-monochlorodibenzo-p-dioxin (2MCDD), at similar rates. Neither PR2 nor PR3 transformed 2,7-dichlodibenzo-p-dioxin (2,7DCDD). An angular dioxygenase 99.7% identical to that in Terrabacter sp. DBF63 was detected by PCR in Janibacter PR1 and Agromyces PR2. PCR did not detect an angular dioxygenase in Arthrobacter PR3. In this work, novel aerobic bacterial strains that can aerobically degrade the products of dechlorination were identified in surficial Passaic River sediments. The presence of these bacteria could enable an in situ treatment process that completely removes all CDDs from the sediment. [ABSTRACT FROM AUTHOR]

Sphingomonas wittichii RW1 is one of a few strains known to grow on the related compounds dibenzofuran (DBF) and dibenzo-p-dioxin (DXN) as the sole source of carbon. Previous work by others (B. Happe, L. D. Eltis, H. Poth, R. Hedderich, and K. N. Timmis, J Bacteriol 175:7313-7320, 1993, https://doi.org/10.1128/jb.175.22.7313-7320.1993) showed that purified DbfB had significant ring cleavage activity against the DBF metabolite trihydroxybiphenyl but little activity against the DXN metabolite trihydroxybiphenylether. We took a physiological approach to positively identify ring cleavage enzymes involved in the DBF and DXN pathways. Knockout of dbfB on the RW1 megaplasmid pSWIT02 results in a strain that grows slowly on DBF but normally on DXN, confirming that DbfB is not involved in DXN degradation. Knockout of SWIT3046 on the RW1 chromosome results in a strain that grows normally on DBF but that does not grow on DXN, demonstrating that SWIT3046 is required for DXN degradation. A double-knockout strain does not grow on either DBF or DXN, demonstrating that these are the only ring cleavage enzymes involved in RW1 DBF and DXN degradation. The replacement of dbfB by SWIT3046 results in a strain that grows normally (equal to the wild type) on both DBF and DXN, showing that promoter strength is important for SWIT3046 to take the place of DbfB in DBF degradation. Thus, both dbfB- and SWIT3046-encoded enzymes are involved in DBF degradation, but only the SWIT3046-encoded enzyme is involved in DXN degradation. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLED) based on phosphorescent emitter promise 100 % internal quantum efficiency (IQE) theoretically, showing extensive applications in various fields. The guest phosphors are usually doped into appropriate host matrices to minimize unnecessary excitons quenching. Herein, three novel bipolar host materials (H1–H3) were developed. Pyridine or pyrimidine was selected as the electron-transporting n-type unit and indolocarbazole as hole-transporting p-type unit. Dibenzofuran was grafted onto the central pyridine or pyrimidine to enhance the electron-transporting ability based on its electron-deficient feature. Furthermore, dibenzofuran was also useful to enhance the thermal and amorphous stabilities of the generated host materials. These host materials are characterized by high glass transition temperatures over 150 °C and suitable energy levels. Thanks to strengthened microcavity effect, the top-emitting green phosphorescent OLEDs containing these hosts in emitting layer realized quite narrow spectra with full width at half maxima (FWHM) of ≤27 nm. Low turn on voltage of 2.01 V, high external quantum efficiency (EQE) up to 41.1 % and pretty stable emission color with ΔCIEy≤0.002 were achieved for these green devices. Moreover, these devices are characterized by extraordinary efficiency stability. A high EQE of 34.9 % was still remained at extremely high brightness of 10000 cd/m2, corresponding to an efficiency roll-off of less than 15 %. These host materials may find practical applications in highly efficient and stable OLED displays. Three novel host materials with suitable energy levels and good thermal stability were designed and cooperated with Ir(ppy) 3 as emitting layer in top-emitting phosphorescent organic light-emitting diodes, which presented narrow spectra with full widths at half maximum of ≤27 nm, stable emission color with ΔCIEy≤0.002, high external quantum efficiencies up to 41.1 % and negligible efficiency roll-offs under high current densities. [Display omitted] • Bipolar hosts were acquired using indolocarbazole and pyridine/pyrimidine as hole- and electron-transporting units. • Dibenzofuran was grafted onto pyridine/pyrimidine ring to further improve thermal stability and n-type feature. • Structure simulation was performed to elucidate the molecular geometry and electronic properties. • Narrow spectra (FWHM≤27 nm) and high brightness were both advanced taking advantages of microcavity effect. • High EQEs of 41.1 %, 37.6 %, and 36.8 % with quite low efficiency roll-offs (≤15 % at 10000 cd/m2) were realized. [ABSTRACT FROM AUTHOR]

• Seven Malus genotypes differe in growth performance in ARD soil. • Formation of phenolics and phytoalexins in roots is differentially induced by ARD. • Early time points are suggested for assessing changes in phenolics and phytoalexins. • 3-Hydroxy-5-methoxybiphenyl can serve as an early biomarker for ARD. Apple replant disease (ARD) is a globally recognised soil-borne disease, which affects apple orchards and tree nurseries. Biotic factors are considered to be the main causal agent of ARD. Phenolics and phytoalexins were induced in apple roots grown in ARD soil compared to roots grown in disinfested ARD soil. However, the relationship between ARD susceptibility and production of phenolics and phytoalexins in apple roots is still unclear. To answer this question, we cultivated seven Malus genotypes with varying levels of ARD susceptibility (M.26, EMR 2, M.200, G.214, G.935, Selection 4, and MAL0739) in both ARD soil from Heidgraben, Germany, and the same soil after disinfestation by gamma-irradiation (γ-ARD). Despite the overall growth reduction observed for all seven genotypes, three of them, EMR 2, G.935 and MAL0739, showed better performance, as indicated by the ARD susceptibility index (ASI) and differences in their root structure. Phenolics and phytoalexins were differentially induced in the roots grown for four weeks (T4) and eight weeks (T8) in ARD soil compared to γ-ARD soil. Moreover, differences in the total phenolics content (TPC) and the total phytoalexin content among the evaluated Malus genotypes were observed. The biochemical data from the early time point (T4) separated Malus genotypes more effectively compared to that from the late time point (T8). Among the six ARD-induced phytoalexins, 3-hydroxy-5-methoxybiphenyl at T4 can serve as an early biomarker for ARD. Although TPC and total phytoalexin content of the Malus genotypes exhibited no or weak correlation with root and shoot growth reduction, some individual phenolics and phytoalexins showed higher coefficients, suggesting that they might influence the ARD susceptibility of apple rootstocks. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT calculations uncover a plausible mechanism for hydrodeoxygenation of dibenzofuran on Pt (111) surface. • The five-membered-ring opening of tetrahydrodibenzofuran is easier than that of hexahydrodibenzofuran. • Non-consecutive hydrogenation of 2-cyclohexylphenol is preferred to a successive pathway. • Bicyclohexane is most likely to be formed through a radical intermediate. Catalytic hydrodeoxygenation is an efficient method to upgrade the quality of low-temperature coal tar and coal liquefied oil. However, only limited researches are performed on the mechanism of hydrodeoxygenation and, therefore, innovation of more efficient and stable catalysts is less progressed and still remains a challenging subject. In this study, density functional theory calculations are carried out to get a deeper insight in the mechanism of dibenzofuran hydrodeoxygenation on the Pt(111) surface. Calculated energies and activation barriers indicate that five-membered-ring opening of tetrahydrodibenzofuran is easier than that of hexahydrodibenzofuran. Then, the generated intermediate can be preferentially hydrogenated through a non-consecutive pathway to 2-cyclohexylphenol, and would result in multiple radical species. The dehydroxylation of that intermediate formed by adding five hydrogen atoms to the phenyl ring of 2-cyclohexylphenol shows a moderate reaction barrier of 1.07 eV; whereas, dehydroxylation of cyclohexylcyclohexanol needs a higher energy barrier of 2.04 eV. For the hydrodeoxygenation of dibenzofuran on the Pt(111) surface, the target product bicyclohexane is most likely to be formed through a radical intermediate. This investigation may provide a potent theoretical guidance to design new catalyst for hydrodeoxygenation of coal to liquid. [ABSTRACT FROM AUTHOR]

Certain industrial chemicals accumulate in the environment due to their recalcitrant properties. Bioremediation uses the capability of some environmental bacteria to break down these chemicals and attenuate the pollution. One such bacterial strain, designated Pvy, was isolated from sediment samples from a lagoon in Romania located near an oil refinery due to its capacity to degrade dibenzofuran (DF). The genome sequence of the Pvy strain was obtained using an Oxford Nanopore MiniION platform. According to the consensus 16S rRNA gene sequence that was compiled from six 16S rRNA gene copies contained in the genome and orthologous average nucleotide identity (OrthoANI) calculation, the Pvy strain was identified as Pseudomonas veronii, which confirmed the identification obtained with the aid of MALDI-TOF mass spectrometry and MALDI BioTyper. The genome was analyzed with respect to enzymes responsible for the overall biodegradative versatility of the strain. The Pvy strain was able to derive carbon from naphthalene (NP) and several aromatic compounds of natural origin, including salicylic, protocatechuic, p-hydroxybenzoic, trans-cinnamic, vanillic, and indoleacetic acids or vanillin, and was shown to degrade but not utilize DF. In total seven loci were found in the Pvy genome, which enables the strain to participate in the degradation of these aromatic compounds. Our experimental data also indicate that the transcription of the NP-dioxygenase a-subunit gene (ndoB), carried by the plasmid of the Pvy strain, is inducible by DF. These features make the Pvy strain a potential candidate for various bioremediation applications [ABSTRACT FROM AUTHOR]

The yeast strain Moniliella spathulata SBUG-Y 2180 was isolated from oil-contaminated soil at the Tengiz oil field in the Atyrau region of Kazakhstan on the basis of its unique ability to use crude oil and its components as the sole carbon and energy source. This yeast used a large number of hydrocarbons as substrates (more than 150), including n-alkanes with chain lengths ranging from C10 to C32, monomethyl- and monoethyl-substituted alkanes (C9–C23), and n-alkylcyclo alkanes with alkyl chain lengths from 3 to 24 carbon atoms as well as substituted monoaromatic and diaromatic hydrocarbons. Metabolism of this huge range of hydrocarbon substrates produced a very large number of aliphatic, alicyclic, and aromatic acids. Fifty-one of these were identified by GC/MS analyses. This is the first report of the degradation and formation of such a large number of compounds by a yeast. Inoculation of barley seeds with M. spathulata SBUG-Y 2180 had a positive effect on shoot and root development of plants grown in oil-contaminated sand, pointing toward potential applications of the yeast in bioremediation of polluted soils. Key points: • Moniliella spathulata an oil-degrading yeast • Increase of the growth of barley [ABSTRACT FROM AUTHOR]

Stereocalpin B, a new cyclic depsipeptide (1), and a new dibenzofuran derivative (3), were isolated from the Antarctic lichen, Ramalina terebrata (Ramalinaceae), along with a known cyclic depsipeptide (2). The structures of new compounds were characterized by comprehensive spectrometric analyses; high-resolution fast atom bombardment mass spectrometry (HR-FABMS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Stereocalpin B (1) existed in a rotameric equilibrium, which was confirmed using nuclear Overhauser effect spectroscopy (NOESY)/exchange spectroscopy (EXSY) spectrum. Absolute configurations of the amino acid units in 1 were assigned using the advanced Marfey’s method and subsequent NOESY analysis of the 5-hydroxy-2,4-dimethyl-3-oxo-decanoic acid residue confirmed the complete stereochemistry of 1. Compounds 1-3 exhibited moderate antimicrobial activities against E. coli, with the IC50 values ranging from 18–30 μg/mL. Compound 2 exhibited cell growth inhibition against HCT116 cell lines, with the IC50 value of 20 ± 1.20 μM, and compounds 1 and 2 also showed potent anti-inflammatory activities against lipopolysaccharide (LPS)-induced RAW264.7 macrophages with the IC50 values ranging from 5–7 μM.

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• Highly Selective deoxygenation of dibenzofuran to biphenyl was achieved over Co/MoO 3 catalyst. • A strong promotion effect in activity between Co(Ni) and Mo in Co(Ni)/MoO 3 catalysts was observed. • Co(Ni) facilitated reduction of Mo6+ to Mo5+ species, while Ni accelerated over-reduction of Mo5+ to inactive Mo4+. • Co/MoO 3 promoted the cleavage of C-O bond, whereas Ni/MoO 3 tended to the hydrogenation of aromatic ring. • A possible reaction mechanism was proposed. Co(Ni)/MoO 3 catalysts were prepared, characterized and evaluated for the hydrogenolysis of bio-derived dibenzofuran (DBF), aiming at the understanding of the promoting effect of Co/Ni on MoO 3 for high-yield production of aromatic products. All Co(Ni)/MoO 3 catalysts selectively cleaved C-O bond, thus effectively transformed DBF to biphenyl (BP) at relatively moderate conditions. The experimental results from varying Mo species by adjusting the reduction temperature of MoO 3 together with XPS and in-situ XRD characteristic were evident that Mo5+ species was responsible as the major active specie for the reaction. Promotional effect between Co(Ni) and Mo in Co(Ni)/MoO 3 catalysts was observed, resulted from the presence of acidic Co(Ni)MoO 4 species and a large number of Mo5+ species both of which were created local to the Co(Ni)-O-Mo interface, as can be characterized by in-situ XRD, XPS, H 2 -TPR, NH 3 -TPD, in-situ FT-IR, Raman and TEM. The trend of the initial reaction rate follows: MoO 3 (0.18 μmol∙g cat −1∙s−1) < Ni/MoO 3 (0.26 μmol∙g cat −1∙s−1) < Co/MoO 3 (0.29 μmol∙g cat −1∙s−1), corresponding to the decreasing activation barrier. And the best catalytic activity was observed for the 100% yield of BP over Co/MoO 3. A possible mechanism, including Co(Ni) facilitated reduction of Mo6+ to Mo5+ and Co(Ni) enhanced formation of acidic sites, is proposed to be responsible for the high activity in Co(Ni)/MoO 3 catalysts. [ABSTRACT FROM AUTHOR]

The 2,3,4,5-tetrahydro-1H-benzo[2,3]benzofuro[6,5-b]azepine skeleton was built starting from dibenzofuran via 3-aminodibenzofuran, creating the 5-methylene-substituted azepine ring by an intramolecular Heck cyclization. Subsequent modifications led to the endocyclic 4,5-unsaturated analog, the dihydro product, and N-methyl and N-acylated derivatives. All the compounds were obtained in high yields and were fully characterized. Preliminary proliferation assays in a wild-type and a cisplatin-resistant human ovarian carcinoma cell line (A2780 and A2780cisR respectively) indicated that these compounds are moderately cytotoxic, with no significant differences associated with cisplatin resistance. The N-acetyl-5-methylene analog 3 (IC50 = 10 μM), the only one with an exocyclic double bond in conjugation with a benzene ring, was at least twice as active as any other member of the series, suggesting that this structural feature might be associated with higher cytotoxicity. [ABSTRACT FROM AUTHOR]

We report the observation and assignment of the rotational spectra of dibenzofuran measured in the range of 2–6 GHz with a newly constructed broadband chirped-pulse Fourier transform microwave (cp-FTMW) spectrometer. An analysis of the microwave spectra led to the assignment of 40 b-type transitions, resulting in the accurate determination of the rotational constants A=2278.19770(38) MHz, B=601.12248(10) MHz, and C=475.753120(98) MHz. [ABSTRACT FROM AUTHOR]

Anion exchange membrane (AEM) with high ionic conductivity and stable dimension is urgently needed to improve cost-effective anion exchange membrane fuel cells (AEMFC). In this study, a dibenzofuran-containing poly(terphenyl furan piperidinium) (QPTFP) membrane is successfully synthesized in large quantities with a yield exceeding 500 g for the purpose of large-scale AEM production. The introduction of non-rotatable dibenzofurans results in an acceptable swelling ratio of 25 % and high ionic conductivity of 155 mS cm−1 at 80 °C. It also exhibits a favorable tensile strength of 52.6 MPa and excellent alkaline stability of 2200 h at 80 °C in 1 M KOH. Furthermore, the AEMFC employing QPTFP membrane achieves remarkable peak power densities at 80 °C for H 2 –O 2 (2 W cm−2) and H 2 -Air (1.2 W cm−2), and demonstrates excellent stability of over 90 h at 70 °C and a current density of 0.2 A cm−2. [Display omitted] • Poly(aryl furan piperidinium)s are prepared for the continuous production of anion exchange membranes. • The membrane shows the highest conductivity of 155 mS cm−1 and excellent stability of >2200 h. • The fuel cell exhibits the highest peak power density of 2 W cm−2 (H 2 –O 2) and 1.3 W cm−2 (H 2 -Air). • The QPTFP-25 AEM is stabilized of fuel cell operation for 90 h at 70 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two kinds of liquid crystal polymers PMJ0DFM and PMJ6DFM with long-lived room-temperature phosphorescence were synthesized. • The mechanism by which the "Jacketing" effect of mesogen-jacketed liquid crystal polymers to enhance the phosphorescence lifetime was explored in detail. • The application of PMJ0DFM and PMJ6DFM in linearly polarized room-temperature phosphorescence was explored. • Provides new insights for the development of novel long-lived pure organic room-temperature phosphorescent materials. Polymerization is one of the most widely used strategies to achiever RTP. To date, various polymer-based RTP materials have been reported. However, how to improve the phosphorescence lifetime of polymer-based RTP materials still needs to be further researched. In this article, we proposed a new strategy to realize long-lived room-temperature phosphorescence by utilizing the "jacketing" effect of mesogen-jacketed liquid crystal polymers. Two polymers PMJ0DFM and PMJ6DFM with different flexible spacer length were synthesized, and their liquid crystal phase structures and photo-physical properties were systematically investigated. PMJ0DFM formed columnar nematic phase while PMJ6DFM formed a more ordered hexagonal columnar phase liquid crystal. For PMJ0DFM without spacer length, due to the strong "Jacketing" effect, the thermal motion of the chromophore was suppressed, and it was also more conducive to the aggregation and planarization of the chromophores. Therefore, PMJ0DFM film showed longer phosphorescence lifetime and more red-shifted phosphorescence spectrum than PMJ6DFM film. The phosphorescence lifetimes of PMJ0DFM and PMJ6DFM were 355 ms and 247 ms, respectively. In addition, we also explored their application in linearly polarized luminescent materials. When oriented, PMJ0DFM and PMJ6DFM film could emit efficient linearly polarized room temperature phosphorescence. [ABSTRACT FROM AUTHOR]

Novel host materials containing dibenzofuran and dibenzothiophene, (5-(8-(9 H -carbazole-9-yl)dibenzo[ b,d ]furan-2-yl)thiophene-2-yl)diphenylphosphine oxide (3 , CFTPO) and (5-(8-(9H-carbazol-9-yl)dibenzo[ b,d ]thiophen-2-yl)thiophen-2-yl)diphenylphosphine oxide (4 , CTTPO) were synthesized and employed as yellow host materials. The CFTPO host material had bipolar characteristics because it contained carbazole, dibenzofuran, and diphenylphosphine oxide charge transport units with triplet energy (2.56 eV), high external quantum efficiency (24.4%), and power efficiency (63.4 lm/W) in a yellow phosphorescent device. The CTTPO host material also had bipolar characteristics because it contained carbazole, dibenzothiophene, and diphenylphosphine oxide charge transport units with triplet energy (2.52 eV), high quantum efficiency (25.4%), and power efficiency (65.7 lm/W) in a yellow phosphorescent device. [Display omitted] • Carbazole, phosphine oxide, and dibenzofuran/dibenzothiophene based high triplet energy host materials. • High quantum efficiency in yellow phosphorescent organic light-emitting diodes. • High triplet energy for yellow devices. [ABSTRACT FROM AUTHOR]

Five new compounds, eupatodibenzofuran A (1), eupatodibenzofuran B (2), 6-acetyl-8-methoxy-2,2-dimethylchroman-4-one (3), eupatofortunone (4), and eupatodithiecine (5), have been isolated from the aerial part of Eupatorium fortunei, together with 11 known compounds (6‒16). Compounds 1 and 2 featured a new carbon skeleton with an unprecedented 1-(9-(4-methylphenyl)-6-methyldibe nzo[b,d]furan-2-yl)ethenone. Among the isolates, compound 1 exhibited potent inhibitory activity with IC50 values of 5.95 ± 0.89 and 5.55 ± 0.23 μM, respectively, against A549 and MCF-7 cells. The colony-formation assay demonstrated that compound 1 (5 μM) obviously decreased A549 and MCF-7 cell proliferation, and Western blot test confirmed that compound 1 markedly induced apoptosis of A549 and MCF-7 cells through mitochondrial- and caspase-3-dependent pathways.