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The vapor pressures and vaporization enthalpies of dibenzofuran, (−) Ambroxide™ and Galaxolide™ are evaluated by correlation gas chromatography. (−) Ambroxide™ and Galaxolide™ are important commercial products, the latter of which has been the subject of some controversy regarding its impact on the environment. All are cyclic ethers. Dibenzofuran, with established literature values was chosen to evaluate the effectiveness of using hydrocarbons to evaluate both vaporization enthalpies and liquid vapor pressures of simple ethers. Vaporization enthalpy results on dibenzofuran are consistent with the literature value. Current results suggest that hydrocarbons can also be employed to successfully evaluate both liquid vapor pressures and vaporization enthalpies at ambient temperatures for substances for this class of compounds if suitable standards are unavailable.

A home-made analytical instrument based on thermal desorption gas chromatography coupled to resonance enhanced multiphoton ionization time-of-flight mass spectrometry (TD-GC-REMPI-TOFMS) was applied for atline measurement of 1,2,4-trichlorobenzene for the prediction of polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) concentrations in the stack gas of a municipal solid waste incinerator (400 ton/day). Conventional high resolution gas chromatography/high resolution mass spectroscopy (HRGC/HRMS) measurements for the determination of PCDD/F concentrations were performed to compare with TD-GC-REMPI-TOFMS measurements. 1,2,4-Trichlorobenzene correlated with I-TEQ at r = 0.867, 0.953 and 0.944 in unstable, stable and integrated conditions. The correlation was independent of the facility operating conditions observed in this study. Using a linear model to predict I-TEQ by 1,2,4-trichlorobenzene over the test, the average of the relative difference between predicted and measured I-TEQ was 18.9%. 1,2,4-Trichlorobenzene measured by TD-GC-REMPI-TOFMS can be used as a robust indicator of I-TEQ in stack gas.

Herein, a novel route to achieve chiral Meldrum spiro dibenzofuran derivatives was developed, which involved a 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid)-mediated Knoevenagel reaction of substituted aryl halides, followed by a Diels–Alder reaction with euparin as a natural compound. Various multi-substituted Meldrum spiro dibenzofuran derivatives with very high regio- and diastereoselectivity were obtained in excellent yields at room temperature without requiring column chromatography. The synthesized product was further investigated using density functional theory (DFT) to verify the theoretical–experimental reliability; for this purpose, some parameters, including formation energy, solvent energy, chemical hardness, electronic chemical potential, and electrophilicity, were calculated for these compounds in different solvents using the B3LYP/631G(d,p) level of theory. The results of these computations have provided evidence that using quantum-chemical calculations, it is possible to estimate the stability of each product.

The focus of this study is the effects of sulfur and calcium compounds on reducing dioxins in fly ash collected from the baghouse of a pilot-scale fluidized bed combustor. Pelletized sawdust with various amounts of polyvinyl chloride (PVC), pyrite, and calcium hydroxide was used as the feeding material. The experimental results indicated an extremely low concentration of dioxin in the fly ash from the cyclone (0.025 to 0.284 ng g–1), and the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the fly ash collected from the baghouse increased by 27.4% as the chlorine content increased from 0.568 to 1.136 wt%. The inhibition of PCDD/Fs by sulfur is not clear and can be attributed to the low content of copper (average 387 ppm), which serves as the catalyst for the Deacon reaction. Octa-chlorinated dibenzofuran (OCDF) was the major congener of the PCDD/Fs. The highest toxicity-equivalent (I-TEQ) of 2,3,7,8-substituted congeners was 2,3,4,7,8-PeCDF, which accounted for 37% of the total congeners (average value). The correlation between the I-TEQ values and 2,3,4,7,8-PeCDF concentration of fly ash is also discussed.

The present study focuses on hydrocarbons production (bicyclohexane) from hydrodeoxygenation of dibenzofuran over Cu-Ni/Ti-MCM-41 catalysts at mild reaction conditions. The hydrodeoxygenation activity of Cu-Ni/Ti-MCM-41 catalysts was optimized via Ni loading at reaction conditions of 260 °C, 10 MPa and 6 h in batch reactor. Those loading arounds the optimum points (5–10 wt%) were characterized by TPO, RAMAN, XRD, TPR, FESEM and ICP-MS analysis. The catalytic reactions pathway for conversion of dibenzofuran to bicyclohexane were investigated using optimum catalysts (7.5 wt% Ni loading) and reaction mechanism was then proposed. The characterization results showed that Cu-Ni dispersion and catalysts reducibility decreased with continuous increment of Ni loading above 7.5 wt%. The structure activity correlation showed that the dispersion and reducibility enhanced conversions and hydrocarbons selectivity. The highest conversion of dibenzofuran (85.46%) and selectivity of bicyclohexane (58.77%) were found with 7.5% Ni loading. Further addition of Ni loading could lead to decreasing of both activity and selectivity due to poor dispersion and agglomeration as well as low reducibility as Ni loading crossed the optimum points. The product distribution study indicated that the presence of other by-product such as cyclohexyl-benzene, tetra-hydro-dibenzofuran, cyclohexyl-cyclohexanol, cyclohexyl-cyclohexanone, 1-cyclohexyl-cyclohexene, 2-cyclohexyl-phenol. The proposed reaction mechanisms showed that the conversion of dibenzofuran was initiated by partial hydrogenations followed by deoxygenations and subsequently dehydrated to bicyclohexane.

By introducing two novel electron-donating (D) moieties dibenzothiophene (DBT) and dibenzofuran (DBF) as the secondary D groups, we designed and synthesized four novel blue thermally activated delayed fluorescence (TADF) emitters DBTCz-Trz, DBFCz-Trz, BDBTCz-Trz and BDBFCz-Trz. The secondary DBF and DBT segments all significantly participated in the highest occupied molecular orbital (HOMO) delocalization, resulting in effective TADF characteristics and high photoluminescence quantum yields simultaneously for all four emitters. In the devices, DBTCz-Trz and DBFCz-Trz successfully exhibit identical blue emission with a peak at 472 nm and a CIE coordinate of (0.17, 0.28) in the devices, while BDBTCz-Trz and BDBFCz-Trz exhibit cyan emissions. Moreover, the maximum forward-viewing external quantum efficiencies are determined to be as high as 21.7% for DBTCz-Trz, 21.6% for DBFCz-Trz, 23.4% for BDBTCz-Trz, and 25.1% for BDBFCz-Trz, respectively. These results not only prove the great potential of amine-free electron-donating components such as DBF and DBT in constructing TADF emitters for electroluminescence, but they also reveal the importance of extending the frontier orbital molecular distributions for TADF molecular optimization.

Physical chemistry, chemical physics 21(29), 16032 - 16046 (2019). doi:10.1039/C9CP02635E, The structural preferences within a series of dibenzofuran–solvent complexes have been investigated by electronic, vibrational, and rotational spectroscopic methods probing supersonic jet expansions. The experimental study is accompanied by a detailed theoretical analysis including dispersion-corrected density functional theory, symmetry adapted perturbation theory, as well as coupled cluster approaches. The complementary, multi-spectroscopic results reveal a preferred OH⋯O structure for the smallest complex of dibenzofuran–water, whereas for the methanol complex an OH⋯π isomer is simultaneously observed. For the largest complex, dibenzofuran–tert-butyl alcohol, only a π-bound structure is found. These comprehensive investigations show that a completely inverse trend regarding the docking preference is observed by comparing the present results with the ones for analogous diphenyl ether complexes. This can be rationalized on the basis of the planarity/non-planarity and rigidity/flexibility of the different systems, providing valuable insight into the interplay between different non-covalent interactions. This analysis is a further step towards a quantitative description of very delicate energetic balances with the overall goal of yielding reliable structural predictions for non-covalently bound systems., Published by RSC Publ., Cambridge

Conversion of oxygen-containing compounds derived from lignin arises wide interest due to fossil-derived resources consumption and growing environmental concerns. In this work, hydrodeoxygenation (HDO) of dibenzofuran (DBF) was studied over high-surface-area MgO supported Pt, Pd and Ru catalysts at 370 °C and 1.0 MPa. It was determined that the active metals not only affect the catalytic activity, but also change the reaction pathway of HDO of DBF. The intrinsic activity (TOF) of MgO supported catalysts follows the trend: Pt/MgO (0.36 s−1) > Ru/MgO (0.29 s−1) > Pd/MgO (0.09 s−1), companied by the increasing activate barrier. Pt has a high activity in the hydrogenation of DBF, and exhibits a perfect deoxygenation activity followed by hydrogenation (HYD) pathway. Ru shows better cleavage ability of Caromatic O bond and the removal of oxygen from DBF mainly occurs via direct deoxygenation (DDO) pathway. The increased Pt loadings largely promote the conversion of DBF by enhancing both HYD and DDO pathways. In addition, more direct cleavage of Caromatic O bond occurs at higher temperature and the production of aromatics by the DDO pathway prefers the relatively low reaction pressure. Based on the pseudo-first-order kinetics, the analysis of the fitted reaction rate constant shows that the DDO selectivity follows the order: Ru/MgO > Pd/MgO > Pt/MgO, which depends on the capacity of active metals to the cleavage of Caromatic O bond and the hydrogenation of aromatic ring.

The effect of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) distribution of the core structure on the thermally activated delayed fluorescence (TADF) behavior of the TADF emitters was investigated. Dibenzofuran was used as the core structure of the TADF materials, and its 2 and 3 positions were substituted with a donor and an acceptor. Two TADF emitters with the donor and acceptor positions exchanged with each other were synthesized and suggested that the substitution of the donor at the LUMO dominant position and the acceptor at the HOMO dominant position is beneficial to improve the efficiency of the TADF OLEDs. It was described that the substitution positions of the donor and acceptor to the core structure should be managed to increase the quantum efficiency of the TADF devices by enlarged orbital overlap.

While the transformation of carbon monoxide to multicarbon compounds (fuels and organic bulk chemicals) via reductive scission of the enormously strong CO bond is dominated by transition metals, splitting and deoxygenative reductive coupling of CO under nonmatrix conditions using silicon, the second most abundant nonmetal of the earth’s crust, is extremely scarce and mechanistically not well understood. Herein, we report the selective deoxygenative homocoupling of carbon monoxide by divalent silicon utilizing the (LSi:)2Xant 1a [Xant = 9,9-dimethyl-xanthene-4,5-diyl; PhC(NtBu)2] and (LSi:)2Fc 1b (Fc = 1,1′-ferrocenyl) as four-electron reduction reagents under mild reaction conditions (RT, 1 atm), affording the corresponding disilylketenes, Xant(LSi)2(μ-O)(μ-CCO) 2a and Fc(LSi)2(μ-O)(μ-CCO) 2b, respectively. However, the dibenzofuran analogue of 1b, compound 1c, was unreactive toward CO due to the longer distance between the two SiII atoms, which demonstrated the crucial role of the Si···Si distance on coo...

Metabolites of polychlorinated biphenyls (PCBs)—hydroxylated PCBs (OH-PCBs), chlorobenzyl alcohols (CB-OHs), and chlorobenzaldehydes (CB-CHOs)—were incubated in vitro with the extracellular liquid of Pleurotus ostreatus, which contains mainly laccase and low manganese-dependent peroxidase (MnP) activity. The enzymes were able to decrease the amount of most of the tested OH-PCBs by > 80% within 1 h; the removal of more recalcitrant OH-PCBs was greatly enhanced by the addition of the laccase mediator syringaldehyde. Conversely, glutathione substantially hindered the reaction, suggesting that it acted as a laccase inhibitor. Hydroxylated dibenzofuran and chlorobenzoic acid were identified as transformation products of OH-PCBs. The extracellular enzymes also oxidized the CB-OHs to the corresponding CB-CHOs on the order of hours to days; however, the mediated and nonmediated setups exhibited only slight differences, and the participating enzymes could not be determined. When CB-CHOs were used as the substrates, only partial transformation was observed. In an additional experiment, the extracellular liquid of Irpex lacteus, which contains predominantly MnP, was able to efficiently transform CB-CHOs with the aid of glutathione; mono- and di-chloroacetophenones were detected as transformation products. These results demonstrate that extracellular enzymes of ligninolytic fungi can act on a wide range of PCB metabolites, emphasizing their potential for bioremediation.

Existing synthetic routes for accessing dibenzofuran core have intrinsic regioselectivity, limiting the substitution patterns available in heteropolycyclic arene products. Here we report a double 1,4-conjugate addition/intramolecular annulation cascade reaction between propargylamines and two equivalents of imidazolium methylides that allows efficient access of structurally versatile dibenzofurans. This transition metal-free protocol proceeds smoothly under bench-top air atmosphere and offers easy manipulation of substituents on the dibenzofuran core, and also provides good-to-excellent product yields with good functional group tolerance, particularly the –Br and –Cl groups which are often incompatible with existing metal-catalyzed C–C and/or C–O bond ring-forming processes. It is worth noting that ladder-type π-systems with all-arene quarternary carbon structure can be straightforwardly generated upon simple late-stage functionalization. Existing routes to dibenzofurans have intrinsic regioselectivity, limiting the substitution patterns available in the products. Here a double 1,4-conjugate addition-annulation cascade between propargylamines and imidazolium methylides provides direct access to dibenzofurans with a complementary substitution pattern.

Dibenzofuran (DBF) are typical heterocyclic aromatic compounds (O-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this review, Emphasis has already been placed on the reports on synthesis of dibenzofuran derivatives with possessing anti-bacterial activities. It is not a comprehensive discussion of all such compounds, but is instead intended to illustrate the range of anti-bacterial activity possessed by such compounds, the variety of sources from which they can be synthesized, and the various synthetic methods by which they can be prepared. Compounds with reduced benzene rings (such as morphine and its derivatives) are not included in this review, nor are compounds in which an aromaticity is disrupted by alkylation, as with usnic acid.

Recently, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) have been attracting considerable attention owing to their high toxicity. Understanding their formation mechanism during combustion processes is important to control their emission. However, there are few studies that have quantitatively investigated OPAH formation in the fuel-rich oxidation of hydrocarbons, despite the availability of several studies on PAH formation. In this study, benzofuran and dibenzofuran as OPAHs were quantified in the fuel-rich oxidation of toluene using a flow reactor at atmospheric pressure in a temperature range of 1050-1350 K at equivalence ratios from 3.0 to 12.0 and residence times from 0.2 to 1.5 s. In addition to benzofuran and dibenzofuran, 4 types of monocyclic aromatic hydrocarbons and 19 types of PAHs were also evaluated. The experimental data obtained in this study were compared with those of the ethylene oxidation performed in our previous study. The existing kinetic model for PAH growth was modified based on several theoretical studies to predict the behavior of OPAHs with furan structures. The modified model showed significant improvements in the prediction of benzofuran and dibenzofuran formation. Based on the rate of production and sensitivity analysis using the modified model, the dominant reaction pathways of benzofuran and dibenzofuran were investigated.

Two novel sulfur-containing dibenzofurans, sorbusins A (1) and B (2), two unprecedented biphenyl glycosides, 2′-hydroxyaucuparin 2′-O-ɑ-L-rhamnoside (3) and noraucuparin 5-O-ɑ-L-rhamnoside (4), and four known analogues (5–8), were isolated from Sorbus pohuashanensis suspension cell induced by yeast extract. Their structures were elucidated based on spectroscopic analyses and quantum calculation of 13C NMR data. Structurally, compound 1 possessed a rare naturally occurring benzothiazole moiety and represents the first example of thiazole fused dibenzofuran. A plausible biosynthetic pathway for the sulfur-containing dibenzofurans is proposed. These dibenzofuran and biphenyl phytoalexins were evaluated for their antimicrobial activities against pathogenic fungi and drug-resistant bacteria. Compound 7 exhibited significant antibacterial activity against methicinllin-resistant Staphylococcus aureus with an MIC value of 3.13 μg/mL.

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).

The amount of steel produced using electric arc furnaces (EAFs) has been increasing in recent years. In this study, stack gases from EAFs in steelmaking plants were analyzed to determine if they are also dominant sources of polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/F) emissions in China. Isotope dilution high-resolution gas chromatography high-resolution mass spectrometry for qualitative and quantitative analysis of PBDD/F congeners revealed that the mean PBDD/F mass concentrations were 271.1-9467.8 pg Nm-3 for the preheating stages (PS) of three EAF plants and that the corresponding toxic equivalents (TEQs) were 10.8-971.2 pg TEQ Nm-3. The PBDD/F mass concentration from the smelting stage (SS) at plant E3 was 261.9 pg Nm-3 (4.5 pg TEQ Nm-3). The PBDD/F emission factors (EF) during the preheating stage for the three plants were 0.0356-1.51 μg TEQ t-1, and the EF was 0.0359 μg TEQ t-1 during the E3 smelting stage. PBDD/Fs were found to contribute 2.39-67.85% to the total mass and 2.84-57.68% to the total dioxin TEQ. These wide fluctuations were caused by differences in the composition of feeding materials and the working temperature of bag filters. Overall, the results indicate that PBDD/F emissions from EAF steelmaking should receive increased attention. The PBDD/F congener patterns among the three EAF plants were variable, possibly because of differences in raw materials. The results presented herein will facilitate assessment of the contribution of EAFs to total PBDD/F emissions in China and investigations of PBDD/F emissions at different stages of steelmaking processes using EAFs.

In this paper, the distribution of methyl dibenzofuran isomers (MDBFs) in petroleum hydrocarbon samples of different ages and sedimentary environments were analyzed by the GC-MS method and relevant software. Relevant parameters of MDBFs were put into several cross-plots that have been studied and can reflect the origin of petroleum hydrocarbon. The results show that the diagram of pristane/phytane (Pr/Ph) - dibenzothiophene/phenanthrene (DBT/P) and the diagram of Pr/Ph - alkyl dibenzothiophene/alkyl dibenzofuran (ADBT/ADBF) cannot distinguish shale derived from marine and lacustrine shale. Whereas the diagram of Pr/Ph - (1 + 4)-/(2 + 3)-MDBF can effectively distinguish. the sedimentary environments and lithologic characteristics of samples. The results show that the diagram of Pr/Ph versus (vs.) (1 + 4)-/(2 + 3)-MDBF are more suitable to reflect the sedimentary environment and lithologic characteristics of organic matters. The method of big data processing can effectively optimize geochemical information.

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 α-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.

Dioxin and dioxin-like compounds are group of chemical compounds that are highly toxic, persistent environmental pollutants that can affect human health, wildlife and environment adversely. Dioxins are ubiquitous in environment (soil, water and air) and are formed mostly as by-products of various industrial activities such as metallurgy, waste incineration or burning. Environmental clean-up of dioxins is extremely difficult partly because of its planner structure, extremely hydrophobic nature, strong adsorption/absorption to the soil. Once released into the environment dioxins can contaminate the human and animal food supply. Dioxin mediated toxicity can result in immune-toxicity, induction of enzyme related disorders, chloracne, carcinogen and birth defects. This chapter details the structure, source, fate, impact on human health and environment, metabolism, biodegradation, enzymes and the genes involved during the biodegradation of dioxin and dioxin-like compounds such as dibenzofuran.

It has been found that usnic acid carbonyl groups can be hydrogenated by the action of H2/Pd(C). Thus, two new dibenzofuran derivatives were synthesized.

Biomarkers identification of aromatic hydrocarbon fraction of Cepu oil samples was carried out to determine the ancient depositional environment, the source of origin and indicators of the maturity of the old well of the Cepu Block oil, Wonocolo Formation, East Java Indonesia. Biomarkers was identified through the Gas Chromatography-Mass Spectroscopy (GC-MS) method. The distribution of aromatic hydrocarbon biomarkers indicates the presence of naphthalene compounds and their derivatives, sesquiterpenoids, diterpenoids and heterocyclic aromatic groups. The presence of identified biomarkers indicates the source of the oil organic compound coming from higher plants Angiosperms. The presence of methyl phenanthrene and aromatic heterocyclic biomarkers such as dibenzothiophene and dibenzofuran , as well as fluorene shows that Cepu Block oil was deposited not only in the terrestrial environment, but also lacustrine and marin under oxidic precipitation conditions. The presence of methyl phenanthrene with MPI value of 0.86 and isocadalene abundance higher than cadalene indicates moderate to high maturity of the Cepu Block oil analyzed. Keywords: Cepu Block oil, aromatic hydrocarbon, biomarker, paleoenvironment, GC-MS analysis.

Nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs, OPAHs) are abundant in the atmosphere and contribute significantly to the health risk associated with inhalation of polluted air. Despite the health hazard they pose, NPAHs and OPAHs were rarely included in monitoring. The aim of this study is to provide the first multi-year temporal trends of the concentrations, composition pattern and fate of NPAHs and OPAHs in air from a site representative of background air quality conditions in central Europe. Samples were collected every second week at a rural background site in the Czech Republic during 2015 -2017. Concentrations ranged from 1.3 to 160 pg m(-3) for Sigma(17)NPAHs, from 32 to 2600 pg m-3 for Sigma(10)OPAHs and from 5.1 to 4300 pg m(-3) for Sigma O-2-heterocycles. The average particulate mass fraction (q) ranged from 0.01 +/- 0.02 (2-nitronaphthalene) to 0.83 +/- 0.22 (1-nitropyrene) for individual NPAHs and from

This study is carried out in two full-scale (300 t/d) municipal solid waste incinerators (MSWI), focusing on the inhibition effect on polychlorinated-ρ-dibenzodioxins and dibenzofurans (PCDD/F) formation by the Sulfur-, Phosphorus-, and Nitrogen-containing inhibitors. The inhibition efficiencies of total PCDD/F range from 45.77 % to 58.55 %, meanwhile, from 50.1 % to 57.6 % for toxic PCDD/F. X-ray photoelectron spectroscopy results conduct the inhibition effect on the three key factors of PCDD/F formation: catalytic metal, carbon source and chlorine source. Inhibitors can increase the proportion of inorganic chlorine form at the ash surface. The changes of sulfur and phosphorus forms support the inhibition mechanisms of PCDD/F. De novo synthesis is the stable inhibition pathway in this study, meanwhile, the chlorophenols-route and dibenzodioxin and dibenzofuran chlorination also work in some tests. The results are the basics for further industrial application of PCDD/F inhibitors and benefit in controlling the PCDD/F emission from MSWI.

In this work, a series of fluorescent cathodically coloring electrochromic (EC) small molecules o-, m-, and p-DBFDCz with 3,5-di(9H-carbazol-9-yl)benzene (DCz) linked to dibenzofuran (DBF) at diffe...

The complete genome sequence of Rhodococcus sp. WAY2 (WAY2) consists of a circular chromosome, three linear replicons and a small circular plasmid. The linear replicons contain typical actinobacterial invertron-type telomeres with the central CGTXCGC motif. Comparative phylogenetic analysis of the 16S rRNA gene along with phylogenomic analysis based on the genome-togenome blast distance phylogeny (GBDP) algorithm and digital DNA–DNA hybridization (dDDH) with other Rhodococcus type strains resulted in a clear differentiation of WAY2, which is likely a new species. The genome of WAY2 contains five distinct clusters of bph, etb and nah genes, putatively involved in the degradation of several aromatic compounds. These clusters are distributed throughout the linear plasmids. The high sequence homology of the ring-hydroxylating subunits of these systems with other known enzymes has allowed us to model the range of aromatic substrates they could degrade. Further functional characterization revealed that WAY2 was able to grow with biphenyl, naphthalene and xylene as sole carbon and energy sources, and could oxidize multiple aromatic compounds, including ethylbenzene, phenanthrene, dibenzofuran and toluene. In addition, WAY2 was able to co-metabolize 23 polychlorinated biphenyl congeners, consistent with the five different ring-hydroxylating systems encoded by its genome. WAY2 could also use n-alkanes of various chain-lengths as a sole carbon source, probably due to the presence of alkB and ladA gene copies, which are only found in its chromosome. These results show that WAY2 has a potential to be used for the biodegradation of multiple organic compounds, This research was funded by GREENER-H2020 (EU), grant number 826312, and MICINN/FEDER EU, grant number RTI2018-0933991- B-I00. D.G.-S. was supported by a MECD FPU fellowship program, grant number FPU14/03965. P.S.-L. was supported by the MICINN FPU fellowship program, grant number FPU18/02169. E.B.-R. was supported by the MECD FPU fellowship program, grant number FPU16/05513. J.S., T.C. and O.U. acknowledge Czech Science Foundation grant number 17–00227S, which enabled PCB co-metabolism experiments to be undertaken

A series of first examples of dibenzofuran (DBF)/dibenzothiophene (DBT)-embedded dithia-bis(calix)-sapphyrins were synthesized by condensing 1 equiv of dibenzofuran/dibenzothiophene-based tripyrran...

This research was funded by European Social Fund (Project No 09.3.3-LMT-K-712-02-0105). DG acknowledges to the ERDF PostDoc grant No. 1.1.1.2/VIAA/1/16/177., In the search of universal host materials for organic light emitting diodes a new series of bipolar host materials containing methoxy-substituted carbazoles as the electron-donating and dibenzofuran as an electron-accepting units were designed and synthesized. Different linking topologies and number of methoxy groups attached to carbazolyl moiety were used to understand the impact of the strength of the donor moiety on the thermal, optical, photophysical, electrochemical and electroluminescent properties. The synthesized compounds exhibited relatively high thermal stability with 5% weight loss temperatures exceeding 378 °C and formed molecular glasses with high glass-transition temperatures ranging from 120 to 148 °C. High triplet energy values of 2.86–2.96 eV were estimated for dilute THF solutions at 77K. Hole and electron drift mobilities estimated using time-of-flight technique in solid layers approached 10−4 cm2V−1s−1 at high electric fields exceeding 3.6 × 105 V cm−1. The synthesized methoxy-carbazole based compounds were tested as hosts in electrophosphorescent and TADF organic light-emitting diodes reaching luminance of 53000 cd m−2 and external quantum efficiency of 12.5%, in the best case., European Social Fund 09.3.3-LMT-K-712-02-0105; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART², https://www.sciencedirect.com/science/article/pii/S0143720819311623

In this paper, a new data set of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) half-lives (HLs) in soil is presented. Data are derived from a greenhouse experiment performed with an aged contaminated soil under semi-field conditions, obtained from a National Relevance Site (SIN) located in Northern Italy (SIN Brescia-Caffaro). Ten different treatments (combination of seven plant species with different soil conditions) were considered together with the respective controls (soil without plants). The ability of the plants to stimulate the biodegradation of these compounds was evaluated by measuring the PCDD/F concentration reduction in soil over a period of 18 months. The formation of new bound residues was excluded by using roots as a passive sampler of bioaccessible concentrations. The best treatment which significantly reduced PCDD/F concentrations in soil was the one with Festuca arundinacea (about 11-24% reduction, depending on the congener). These decreases reflected in HLs ranging from 2.5 to 5.8 years. Simulations performed with a dynamic air-vegetation-soil model (SoilPlusVeg) confirmed that these HLs were substantially due to biodegradation rather than other loss processes. Because no coherent PCDD/F degradation HL data sets are currently available for soil, they could substantially improve the predictions of soil remediation time, long-range transport, and food chain transfer of these chemicals using multimedia fate models.

Among boron-containing fluorescent probes, fluorescein modified by dihydroxyboron is rarely reported as a probe for detecting contaminants. For the first time, a non-covalent ratiometric fluorophore (NRF) was synthesized based on the interactive reaction between 4,5-bis-dihydroxyboron fluorescein and dibenzofuran. The optimized synthetic conditions for NRF were 1 mmol% Ni(dppp)Cl2 as a catalyst, 5 mmol% PPh3 as an additive, room-temperature reaction, and 72-h stirring, and in such cases, the yield reached as high as 91%. At the 290-nm excitation wavelength, the NRF molecules produced dual-emitting phenomenon at 315 and 560 nm. When fenpropathrin as a representative species of pyrethroid pesticides (Pys) was added, the 315-nm fluorescence intensities (FIs) were dramatically decreased, whereas the 560-nm FIs were slightly changed. Therefore, the ratios (I560/I315) of 560-nm FIs to 315-nm FIs could be utilized as an appropriate ratiometric indicator for sensitive Pys detection. Optimized conditions for the ratiometric probe were 60-min incubation and neutral solution pH; under such circumstances, the linear range, limit of detection and fortified recoveries for Pys were 5–150 μg·L−1, 1.5 μg·L−1 and 97.55–105.90%, respectively, which are comparable or even better than those of previously reported methods. As verified by certified reference material in apple juice (QC-198B-1), the NRF probe yielded a highly relative recovery up to 98.25% for fenpropathrin. Common salts and other pesticides had little effect on the ratiometric indicator of NRF, evidencing good selectivity and specificity for Pys. Collectively, this ratiometric probe shows great prospects in application for trace-level Pys detection in daily food monitoring.

There is great concern about decreasing the amounts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) that are formed and emitted during the chlorine bleaching of pulp. The formation of PCDD/Fs during non-woodpulp chlorine bleaching was investigated in the study described here. Wheat straw was separated into three components, cellulose, hemicellulose, and lignin. Chlorination experiments were performed, and lignin and hemicellulose contributed more than cellulose to PCDD/F formation when the pulp was bleached using chlorine. The chemical components of lignin were identified by gas chromatography mass spectrometry, and nine possible PCDD/F precursors were quantified by gas chromatography tandem mass spectrometry. Spiked chlorination experiments were performed to investigate the effects of these compounds on PCDD/F formation. 4-Ethyl-2-methoxyphenol had the strongest effect on PCDD/F formation, followed by p-chlorophenol, and guaiacol. All the test compounds promoted polychlorinated dibenzofuran formation but had limited effects on polychlorinated dibenzo-p-dioxin formation. The results allowed mechanisms for the formation of PCDD/Fs from phenol, chlorophenol, catechol, and guaiacol to be proposed.

Syntheses of 1,2-, 1,3-, 1,4-, 1,8-, 2,4-, 3,4-, 4,8-, 1,2,4-, 1,2,8- and 1,3,4-functionalized dibenzofurans in few steps with good to excellent yields starting from dibenzofuran-1-ol or -4-ol are presented. These rapidly accessible bi- or tri-functionalized building blocks are of great interest for the synthesis of bioactive substances or functional material development. Furthermore, for intermediates containing both a bromine and a triflate moiety, a selective mono-substitution by means of Suzuki-Miyaura reaction (SMR) is described.

An efficient synthesis of a variety of dibenzofuran derivatives via Cu-catalyzed cyclization diaryliodonium salts in water is achieved. Various dibenzofuran derivatives could be obtained in good to excellent yields via this oxygen–iodine exchange approach. A concise synthesis of organic semiconducting material molecule has been achieved using this method.

Regioselective functionalization of core per-substituted boron dipyrromethenes (BODIPYs) has been achieved efficiently based on tetrabromoBODIPY, which affords a series of dibenzofuran-fused chromophores, via a regioselective nucleophilic substitution reaction followed by direct palladium-catalyzed two-fold intramolecular ring fusion. These rigid dibenzofuran-fused BODIPYs showed impressive photophysical properties such as clearly red-shifted absorption and emission bands, enhanced absorption coefficients upon and intense fluorescence (close to unity).