Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Single-junction fullerene solar cells with 10% efficiency and high open-circuit voltage approaching 1 V
No full textIt has been proven that the introduction of F atom and the replacement of alkyl side-chain with alkylthio substituent could be the effective side-chain strategies, to obtain the deep highest occupied molecular orbital (HOMO) energy level with little influence on the optical absorption, and in turn, the small photo energy loss (E-loss). In this work, we combine the advantages of D-A(pi)-Q-A(pi) strategy and the above side chain engineering, to construct a series of high-performance polymers P1-P3 with high open-circuit voltage (V-OC) of exceeding 0.90 V in the conventional solar cells. Meanwhile, small E(loss)s of 0.73-0.78 eV are achieved accompanying high V-OC and almost unchanged optical bandgaps of similar to 1.70 eV, which are the smaller values in comparison with that of the other high-performance polymer systems. More encouragingly, P2-based solar cells exhibit high PCE of 10.30% and V-OC of 0.97 V, which is one of the highest values for polymer/fullerene based solar cells. Our work not only demonstrates a series of high-efficiency new materials, but also strongly confirms that the combination of D-A(pi)-Q-A(pi) arrangement and rational side chain engineering is a very promising strategy to construct high-performance photovoltaic polymers with reduced energy loss
Gas phase hydrodeoxygenation of anisole and guaiacol to aromatics with a high selectivity over Ni-Mo/SiO2
No full textA very active Ni-Mo bimetallic catalyst supported on SiO2 was prepared for the hydrodeoxygenation (HDO) reaction of anisole and guaiacol under a H-2 partial pressure of 83 kPa. Generally, transition metal and their oxides were thought to have less HDO activity than others, such as sulfides, carbides, phosphides. However, this work achieved a novel deoxygenation result, where a high conversion (98.7%) at 673-693 degrees C and atmospheric pressure for the model compounds and high selectivity ( > 96%) to aromatic hydrocarbons (BTX) were obtained. Furthermore, the methyl transfer reaction is greatly promoted by abundant acid sites of the catalyst, leading to a low carbon-loss. The present work provides a promising way and new insight for an economic and efficient HDO process for the lignin-derived thermal degradation products
Evaluation and comparison of N-cycloalkylformylated chitosan bis(arylcarbamate)s as chiral selectors for enantioseparation
No full textIn order to systematically investigate the structural dependence on the properties of N-cycloalkyl-formylated chitosan bis(arylcarbamate)s, 3,5-dimethylphenylcarbamates of N-cyclopropylformylated, N-cyclobutylformylated, N-cyclopentylformylated and N-cyclohexylformylated chitosans were prepared as chiral selectors in the present study. Since both the molecular weights of chitosan and the substituents at the 3- and 6-positions of the phenylcarbamates are identical, the influences of the substituent at the 2-position on the solvent tolerability and enantioseparation performance of the chiral selectors were specifically compared and discussed. It was found that the solvent tolerability and enantioseparation performances of the chiral selectors obviously differed with the variation of the substituent at the 2-position of the glucosamine skeleton. Although all the chiral selectors generally showed satisfactory tolerability in ethyl acetate and acetone, the chiral selector with a three-membered ring exhibited much more preferable tolerability against tetrahydrofuran than the others with a four-, five- or six-membered ring. Enantioseparation results revealed that most of the chiral selectors exhibited powerful chiral recognition and enantioseparation abilities, and the chiral selector with a five-membered ring exhibited the best enantioseparation performance. The corresponding coated-type chiral stationary phases prepared from these chitosan-based chiral selectors were able to be complementary with each other and applied as promising chiral separation materials for enantiomeric separations
Single-step production of the simvastatin precursor monacolin J by engineering of an industrial strain of Aspergillus terreus
No full textMonacolin J is a key precursor for the synthesis of simvastatin (Zocor), an important drug for treating hypercholesterolemia. Industrially, monacolin J is manufactured through alkaline hydrolysis of lovastatin, a fungal polyketide produced by Aspergillus terreus. Multistep chemical processes for the conversion of lovastatin to simvastatin are laborious, cost expensive and environmentally unfriendly. A biocatalysis process for monacolin J conversion to simvastatin has been developed. However, direct bioproduction of monacolin J has not yet been achieved. Here, we identified a lovastatin hydrolase from Penicillium chrysogenum, which displays a 232-fold higher catalytic efficiency for the in vitro hydrolysis of lovastatin compared to a previously patented hydrolase, but no activity for simvastatin. Furthermore, we showed that an industrial A. terreus strain heterologously expressing this lovastatin hydrolase can produce monacolin J through single-step fermentation with high efficiency, approximately 95% of the biosynthesized lovastatin was hydrolyzed to monacolin J. Our results demonstrate a simple and green technical route for the production of monacolin J, which makes complete bioproduction of the cholesterol-lowering drug simvastatin feasible and promising
Complete elucidation of the late steps of bafilomycin biosynthesis in Streptomyces lohii
No full textBafilomycins are an important subgroup of polyketides with diverse biological activities and possible applications as specific inhibitors of vacuolar H+-ATPase. However, the general toxicity and structural complexity of bafilomycins present formidable challenges to drug design via chemical modification, prompting interests in improving bafilomycin activities via biosynthetic approaches. Two bafilomycin biosynthetic gene clusters have been identified, but their post-polyketide synthase (PKS) tailoring steps for structural diversification and bioactivity improvement remain largely unknown. In this study, the post-PKS tailoring pathway from bafilomycin A(1) (1)-> C-1 (2)-> B-1 (3) in the marine microorganism Streptomyces lohii was elucidated for the first time by in vivo gene inactivation and in vitro biochemical characterization. We found that fumarate is first adenylated by a novel fumarate adenylyltransferase Orf3. Then, the fumaryl transferase Orf2 is responsible for transferring the fumarate moiety from fumaryl-AMP to the 21-hydroxyl group of 1 to generate 2. Last, the ATP-dependent amide synthetase BafY catalyzes the condensation of 2 and 2-amino-3-hydroxycyclopent-2-enone (C5N) produced by the 5-aminolevulinic acid synthase BafZ and the acyl-CoA ligase BafX, giving rise to the final product 3. The elucidation of fumarate incorporation mechanism represents the first paradigm for biosynthesis of natural products containing the fumarate moiety. Moreover, the bafilomycin post-PKS tailoring pathway features an interesting cross-talk between primary and secondary metabolisms for natural product biosynthesis. Taken together, this work provides significant insights into bafilomycin biosynthesis to inform future pharmacological development of these compounds
Hydroxylation of Compactin (ML-236B) by CYP105D7 (SAV_7469) from Streptomyces avermitilis
No full textCompactin and pravastatin are competitive cholesterol biosynthesis inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase and belong to the statin drugs; however, the latter shows superior pharmacokinetic characteristics. Previously, we reported that the bacterial P450, CYP105D7, from Streptomyces avermitilis can catalyze the hydroxylation of 1-deoxypentalenic acid, diclofenac, and naringenin. Here, we demonstrate that CYP105D7 could also catalyze compactin hydroxylation in vitro. In the presence of both bacterial and cyanobacterial redox partner systems with an NADPH regeneration system, the reaction produced two hydroxylated products, including pravastatin (hydroxylated at the C6 position). The steady-state kinetic parameters were measured using the redox partners of putidaredoxin and its reductase. The K-m and k(cat) values for compactin were 39.1 +/- 8.8 mu M and 1.12 +/- 0.09 min(-1), respectively. The k(cat)/K-m value for compactin (0.029 min(-1)center dot mu M-1) was lower than that for diclofenac (0.114 min(-1)center dot mu M-1). Spectroscopic analysis showed that CYP105D7 binds to compactin with a K-d value of 17.5 +/- 3.6 mu M. Molecular docking analysis was performed to build a possible binding model of compactin. Comparisons of different substrates with CYP105D7 were conclusively illustrated for the first time
Catalytic Abatement of Nitrous Oxide Coupled with Ethane Oxydehydrogenation over Mesoporous Cr/Al2O3 Catalyst
No full textWaste nitrous oxide (N2O) was utilized as an oxidant for ethane oxydehydrogenation reaction at the temperature range from 450 degrees C to 700 degrees C over the mesoporous Cr/Al2O3 catalyst synthesized via the one-pot evaporation-induced self-assembly (EISA) method. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption-desorption analysis. The obtained mesoporous material with favorable textural property and advantageous thermal stability was investigated as the catalyst for ethane oxydehydrogenation. It was found that the utilization of N2O as an oxidant for the oxydehydrogenation reaction of ethane resulted in simultaneous and complete N2O abatement. Moreover, the catalytic conversion of C2H6 to C2H4 was increased from 18% to 43% as the temperature increased from 450 degrees C to 700 degrees C. The increased N2O concentration from 5 vol % to 20 vol % resulted in an increased ethane conversion but decreased ethylene selectivity because the nonselective reactions occurred. Ethane was converted into ethylene with approximately 51% selectivity and 22% yield at 700 degrees C and N2O concentration of 10%. After a catalytic steady state was reached, no obvious decline was observed during a 15 h evaluation period
A novel naphthyl side-chained benzodithiophene polymer for efficient photovoltaic cells with a high fill factor of 75%
No full textTo study which strategy (extending side chain pi-conjugation with single-bonded or fused aromatic rings) is more effective in improving the photovoltaic properties of benzodithiophene (BDT)-based polymers, naphthyl (NP) and biphenyl (BP) units were introduced to the BDT core as conjugated side chains. Two polymers PBDTNP-DTBO and PBDTBP-DTBO based on NP or BP-substituted BDT and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]oxadiazole (DTBO) were designed. These two polymers only exhibited small differences in the chemical structure, but great differences in photovoltaic performance. PBDTNP-DTBO showed a high power conversion efficiency (PCE) of 8.79%, with an open-circuit voltage (V-oc) of 0.82 V, a short-circuit current density (J(sc)) of 14.34 mA cm(-2), and a fill factor (FF) of 74.73%, while PBDTBP-DTBO only showed a maximum PCE of 6.69%, with a V-oc of 0.75 V, a J(sc) of 13.55 mA cm(-2), and a FF of 65.86%. Hence, extending the side chain pi-conjugation system of a BDT-based polymer with naphthyl is a more effective method to enhance the photovoltaic properties
Photodimerization Kinetics of a Styrylquinoline Derivative in Langmuir-Blodgett Monolayers Monitored by Second Harmonic Generation
No full textTo explore the influence of surface packing densities on the interfacial photochemical kinetics, the surface-selective second harmonic generation (SHG) technique was used to investigate the kinetics of two-photon induced [2 + 2] photocycloadditions of a styrylquinoline alkoxy derivative within the Langmuir-Blodgett (LB) monolayers. The laser power dependence experiment revealed that this interfacial photodimerization is a first-order reaction, which implies that the photoexcitation is the rate-limiting step. Interestingly, a comparison of photodimerization kinetics at different surface packing densities shows a nonmonotonic distribution of reaction rate constants, which can be attributed to a result of combined effects of the topochemical mechanism and steric hindrance. The atomic force microscopy measurements and theoretical calculations were also employed to help understand the [2 + 2] photocycloaddition mechanisms. The results presented in this work demonstrate that the surface packing density plays an important role in regulating the interfacial photoreactions within the LB monolayers composed of the conjugated aromatic molecular systems
High-Performance Field-Effect Transistor Based on Novel Conjugated P-o-Fluoro-p-alkoxyphenyl-Substituted Polymers by Graphdiyne Doping
No full textThe novel two-dimensional graphitic material, graphdiyne (GDY), has attracted great interest due to its superior stability and natural semiconductor characteristic. We realize the obvious improvement of carrier transport characteristics of P-o-FBDTP C8DTBTff (PFC; o-FBDTP, o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b']dithiophene; C8DTBTff, 5,6-difluoro-4,7di(4-(2-ethylhexyl)-2-thienyl)-2,1,3-benzothiadiazole) organic polymer semiconductor via adding GDY. The result of the field effect transistor measurement suggests that doping GDY can dramatically improve the on/off ratio and threshold voltage of the organic semiconductor. Especially the mobility of GDY/PFC film is 2 orders of magnitude higher than that of pristine PFC, demonstrating the important role of GDY dopant. Besides, the carrier diffusion length of GDY/PFC film is also enhanced, suggesting the great potential applications of GDY-modified polymer with donor acceptor units in organic photoelectric devices