The effect of trace element addition on anaerobic digestion of food industry- and household waste was studied using two semi-continuous lab-scale reactors, one (R30+) was supplied with Fe, Co and Ni, ...while the other (R30) acted as a control. Tracer analysis illustrated that methane production from acetate proceeded through syntrophic acetate oxidation (SAO) in both digesters. The effect of the trace elements was also evaluated in batch assays to determine the capacity of the microorganisms of the two digesters to degrade acetate, phenyl acetate, oleic acid or propionate, butyrate and valerate provided as a cocktail. The trace elements addition improved the performance of the process giving higher methane yields during start-up and early operation and lower levels of mainly acetate and propionate in the R30+ reactor. The batch assay showed that material from R30+ gave effects on methane production from all substrates tested. Phenyl acetate was observed to inhibit methane formation in the R30 but not in the R30+ assay. A real-time PCR analysis targeting methanogens on the order level as well as three SAO bacteria showed an increase in Methanosarcinales in the R30+ reactor over time, even though SAO continuously was the dominating pathway for methane production. Possibly, this increase explains the low VFA-levels and higher degradation rates observed in the R30+ batch incubations. These results show that the added trace elements affected the ability of the microflora to degrade VFAs as well as oleic acid and phenyl acetate in a community, where acetate utilization is dominated by SAO.
Reaction of alkyl isocyanides, phenyl vinyl selenone, and water in the presence of a catalytic amount of Cs2CO3 afforded oxazolidin‐2‐ones in good yields. This unprecedented heteroannulation process ...created four chemical bonds in a single operation with the isocyano group acting formally as a polarized double bond and phenyl vinyl selenone as a latent 1,3‐dipole. The phenylselenonyl group played a triple role as an electron‐withdrawing group to activate the 1,4‐addition, a leaving group, and a latent oxidant in this transformation.
Pluripotent group: A formal 2+2+1 cycloaddition of isonitriles, phenyl vinyl selenone, and water afforded oxazolidin‐2‐ones by formation of four chemical bonds in good yields (see scheme). The isocyano group acted formally as a polarized double bond and phenyl vinyl selenone as a latent 1,3‐dipole. The phenylselenonyl group served as an electron‐withdrawing group to activate the 1,4‐addition, a leaving group and a latent oxidant in this transformation.
Chemical structures of six laminar premixed benzene/oxygen/argon flames with equivalence ratios from 0.75 to 2.0 were investigated at 30Torr. Dozens of flame species, especially radicals and large ...aromatics, were qualitatively identified and quantitatively measured using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). A kinetic model was developed from our previous models of aromatic fuels to simulate the decomposition of benzene and formation of large aromatics, and was validated against the measured mole fraction profiles of flame species. Based on the rate of production analysis in the leanest and richest flames, the decomposition processes of benzene and the fate of C6 and smaller products were discussed in detail. Benzene, phenyl radical and cyclopentadienyl radical are concluded as key precursors of large aromatics, and the low formation of PAHs in rich benzene flames compared with rich alkylbenzene flames mainly derives from the low production of benzyl radical, which is consistent with the observed trends of the sooting tendencies of benzene and alkylbenzenes in previous studies.
Interaction between adsorbed t-butyl peroxybenzoate and photoexcited graphene rendered trapped phenyl and t-butoxy radicals. Post-irradiation thermal desorption showed benzene, t-butanol, and ...isobutylene oxide as the end products. The required hydrogen atoms were obtained via the radical disproportionation. Graphene enabled radical species to be captured and their on-surface chemistry to be revealed.
The crossed beam reactions of the phenyl radical (C6H5, X2A1) with 1,3-butadiene (C4H6, X1Ag) and D6-1,3-butadiene (C4D6, X1Ag) as well as of the D5-phenyl radical (C6D5, X2A1) with ...2,3-D2-1,3-butadiene and 1,1,4,4-D4-1,3-butadiene were carried out under single collision conditions at collision energies of about 55 kJ mol–1. Experimentally, the bicyclic 1,4-dihydronaphthalene molecule was identified as a major product of this reaction (58 ± 15%) with the 1-phenyl–1,3-butadiene contributing 34 ± 10%. The reaction is initiated by a barrierless addition of the phenyl radical to the terminal carbon atom of the 1,3-butadiene (C1/C4) to form a bound intermediate; the latter underwent hydrogen elimination from the terminal CH2 group of the 1,3-butadiene molecule leading to 1-phenyl-trans-1,3-butadiene through a submerged barrier. The dominant product, 1,4-dihydronaphthalene, is formed via an isomerization of the adduct by ring closure and emission of the hydrogen atom from the phenyl moiety at the bridging carbon atom through a tight exit transition state located about 31 kJ mol–1 above the separated products. The hydrogen atom was found to leave the decomposing complex almost parallel to the total angular momentum vector and perpendicularly to the rotation plane of the decomposing intermediate. The defacto barrierless formation of the 1,4-dihydronaphthalene molecule involving a single collision between a phenyl radical and 1,3-butadiene represents an important step in the formation of polycyclic aromatic hydrocarbons (PAHs) and their partially hydrogenated counterparts in combustion and interstellar chemistry.
Comparison between chiroptical spectra and theoretical predictions is the method of choice for the assignment of the absolute configuration of chiral compounds in solution. Here we report the case of ...an apparently simple biarylcarbinol, whose electronic circular dichroism (ECD) in the
L
region exhibits a peculiar alternation of negative and positive bands. Adopting Density Functional Theory, and describing solvent effects with implicit methods, we found three stable conformers in ethanol, each of them with two close lying states corresponding to similar local
L
excitations on the two phenyls. We computed the corresponding vibronic ECD spectra in harmonic approximation, including Duschinsky mixings as well as both Franck Condon (FC) and Herzberg Teller (HT) effects. Exploiting a recently developed mixed quantum/classical method, we further investigated the contribution of the vibronic spectra of out-of-equilibrium structures along the interconversion path connecting the different conformers. In this way, we achieved a reasonable agreement with experiment and attributed the alternating signs of the bands to the existence of different conformers. The remaining discrepancies with experiment indicate that specific solute-solvent interactions modulate the relative conformers' stabilities, calling for new methods able to combine Molecular Dynamics explorations and vibronic calculations. Moreover, the poor performance of HT approaches and the existence of two closely-lying states suggest the necessity of an improved fully-nonadiabatic vibronic approach. These findings demonstrate that even for such a simple system as the biarylcarbinol investigated here, a full reproduction of the fine details of the ECD spectrum requires the development of new improved methods.
A novel donor–π–acceptor (D–π–A) type polymer of
PBDTT-DTFPQx
composed of a medium electron-donating 5,8-dialkylthienyl substituted benzo1,2-
b
:4,5-
b
′dithiophene (BDTT) moiety and a strong ...electron-accepting 4-fluorophenyl substituted 6,7-dioctyloxyquinoxaline (FPQx) with thiophene π-bridge units was synthesized and characterized, as a donor material for polymer solar cells (PSCs). This polymer exhibits a low optical bandgap of 1.66 eV with an absorption onset of 745 nm, a low-lying HOMO energy level of −5.52 eV, and a hole mobility of 5.05 × 10
−4
cm
2
V
−1
s
−1
. Compared to the reported analogues, PSCs based on
PBDTT-DTFPQx
/PC
71
BM demonstrated an outstanding fill factor (FF) value. With an optimized blend ratio of PBDT-TFQ : PC
71
BM (1 : 4, w/w), a high power conversion efficiency (PCE) of 7.2% was obtained, with an open-circuit voltage (
V
oc
) of 0.87 V, a short-circuit current (
J
sc
) of 11.4 mA cm
−2
, and a FF of up to 73% under AM 1.5G irradiation. The results demonstrate that the introduction of two fluoride atoms onto 4-positions of the phenyl group at the quinoxaline unit by side-chain engineering into the BDTT-
alt
-DTQx type polymers would be a feasible approach to improve photovoltaic properties in PSCs.
Diphenylacetylenes possessing both an n-octyloxy group and a substituent groups (H: 1a, phenyl: 1b, naphthyl: 1c, anthryl: 1d, biphenyl: 1e) were polymerized using TaCl5/n-Bu4Sn. Diarylacetylenes ...having bulky aromatic groups such as α-naphthyl and 9-anthryl cannot afford high-molecular-weight polymer, but the present monomers polymerized to afford relatively high-molecular-weight polymers (Mn = 222,000–596,000) because they have a phenyl spacer between bulky aromatic group and reactive part of C≡C. The solubility of 2a-c and 2e exhibited good solubility in relatively low polar solvents because of long alkyl groups. The emission maxima of 2b-e were all 512 nm, which was longer than that of 2a. No difference of emission maximum among 2b-e were observed in solution. However, the emission maxima in film of 2b, 2c, 2d, and 2e were 530, 526, 524, and 542 nm, respectively. Compared to the emission in solution, that of 2b and 2e in film exhibited large shifts while that of 2c and 2d exhibited smaller shifts. This is because the bulky aromatic groups of naphthyl and anthryl hardly took coplanar structures owing to the steric hindrance.
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•We synthesized poly(diphenylacetylene)s having bulky aromatic rings.•Biphenyl-containing polymer emitted at longer wavelength.•Naphthyl- and anthryl-containing polymers did not show the emission red-shifts.•Aromatic side chains hardly took coplanar structures owing to the steric hindrance.
N-Phenyl-1,8-naphthalimide based fluorescent probes are reported with various positions of dinitrobenzenesulfonyl (DNs) quencher on the phenyl ring. The probe with -DNs at the ortho-position was ...predicted to show better response compared to those with the quencher at the metaand parapositions. The probe showed selective and very fast response (response time, t sub(R) = 1 min) toward thiophenol with 20-fold off-on fluorescence sensitivity. Thiophenol sensing applications by the probe were demonstrated viawater sample analysis and live cell imaging studies.
