Trong nghiên cứu này, vật liệu graphene (GR) được chế tạo từ thanh graphite sử dụng phương pháp bóc tách điện hóa với các loại điện áp khác nhau đặt vào hai đầu điện cực, bao gồm các điện áp không ...đổi 6 V, 8 V, 10 V và kỹ thuật thế bậc thang hai giai đoạn từ 0-2 V và 2-10 V trong môi trường ammonium sulfate (NH4)2SO4. Kết quả chế tạo đã được khảo sát bằng các phép đo thế Zeta, kính hiển vi điện tử quét phát xạ trường (FE-SEM), kính hiển vi lực nguyên tử (AFM) và quang phổ Raman để xác định đặc trưng và cấu trúc của vật liệu GR. Thế Zeta thu được của GR-010 có giá trị -47,7 mV cho thấy hiệu quả phân tán trong môi trường nước, hiệu quả này do khả năng liên kết tốt với các ion âm ở bề mặt và biên của GR. Kết quả đo SEM và AFM cũng chỉ ra bề dày trung bình của các tấm GR-010 thu được vào cỡ 1,8 nm tương ứng 3-5 lớp GR, nhỏ hơn so với các mẫu GR-6, GR-8 và GR-10 tương ứng với các điện áp 6 V, 8 V và 10 V. Kết quả phân tích Raman cũng cho thấy mức độ sai hỏng của GR-010 thấp hơn so với GR-6, GR-8 và GR-10 với tỷ số ID/IG = 0,36.
A novel and practical procedure for the preparation of α-amino secondary amides by the aminocarbonylation of N-Boc-imines using carbamoylsilanes bearing methoxymethyl group as secondary amides source ...is presented herein. The protocol tolerates N-Boc-imines bearing different groups, including aryl, double bond conjugated aryl, heteroaryl and aliphatic groups. The reactions provide good to excellent yields of the products under mild and catalysts-free conditions. The electronic property and the steric hindrance of substituent on the N-Boc-imines affect the reaction.
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•α-Amino amides are the basic subunits of peptides and proteins and are valuable synthetic intermediates.•A method for synthesis of α-amino amide derivatives has been developed.•The protocol tolerated a broad range of N-Boc-imines bearing different groups.•The direct aminocarbonylation of N-Boc-imines using carbamoylsilane as an amide source provide good to excellent yields of the products.•Current methodology will prove to be an attractive alternative to the reported methods for the preparation of α-amino secondary amides.
Facilitating photocarrier separation is deemed to be crucial for enhancing photocatalytic activity of photocatalysts, which has drawn considerable attention recently. Herein, we have adopted soft ...beverage-derived carbon materials to modify Bi2O2CO3 (BOC) and realize highly-efficient enhancement in the photodegradation activity. Take carbonized Fanta (labeled as CFT, which are shaped like microspheres) as an example, BOC nanoflakes are coated on the CFT microspheres to obtain core-shell structured CFT@BOC composites. The photodegradation experiment, performed under simulated-sunlight irradiation for ciprofloxacin (CIP) degradation, demonstrates that the optimal composite 9CFT@BOC has a photodegradation activity increased by 8.75 times over that of single BOC. This phenomenon can be interpreted because of the efficient electron transfer from BOC to CFT and hence the decreasing recombination of the photoelectrons/photoholes. Systematic experimental and density functional theory (DFT) were carried out to elucidate the photocatalytic mechanism of the CFT@BOC composites as well as the CIP decomposition behavior. We have also carbonized other soft beverages (e.g., Dayao, Mirinda and Cola) to modify BOC and observed similar phenomenon for photocatalysis enhancement. The present study offers a new insight for designing excellent photocatalysts in environmental remediation.
•Beverage-derived carbon materials were used to modify photodegradation performance of BOC.•Core-shell CFT@BOC composites exhibit photoactivity 8.75 times higher than that of bare BOC.•The enhanced photodegradation mechanism is attributed to electron transfer from BOC to CFT.•Various influencing factors on the CIP degradation were investigated.•Degradation pathways and mechanism of CIP were experimentally and theoretically elucidated.
Among the existing binary offset carrier (BOC) signal receiving technologies, the dual binary phase-shift keying tracking (DBT), originally designed for alternate BOC (AltBOC) modulated Galileo E5 ...signal and then extended to standard BOC signals, has its unique characteristics. It incorporates both single-band and dual-band processing schemes into a unified and simple structure to meet both requirements of improving ranging precision and anti-jamming. However, in this study, the authors propose that it is problematic to directly extend the DBT technique from the AltBOC signal to the standard BOC signal. The root cause of this problem lies in the fact that the cross-correlation functions between the received standard BOC signal and the local replicas in the upper and lower sidebands are not an ideal correlation triangle as the AltBOC case, but with some ripples. This leads to more complex behaviours when the DBT technique is applied to standard BOC signals. The rigorous theoretical analysis of this technique is given in respect of thermal noise performance in this study, which can be used not only to optimise the tracking loop parameters of DBT but also to compare the tracking performance of DBT and other tracking technologies.
New chiral ligands could be obtained by introducing proline moieties and imidazoline moieties to binaphthyl skeletons. The chiral ligands exhibited balanced rigidity and flexibility which could allow ...the change of the conformations during the reactions on one hand, and could provide sufficient asymmetric induction on the other. The proline moiety could act as a linker connecting the binaphthyl skeletons and the imidazoline moieties as well as a coordinating group for the central metal, and the electronic and steric properties of the imidazoline groups could be carefully fine‐tuned by the use of different substituents. In the presence of Cu(II) catalyst bearing such chiral ligands, aza‐Friedel–Crafts reaction of 1‐naphthols and electron‐rich phenols with isatin‐derived ketimines provided the desired products with good to excellent yields and up to 99 % ee. The reactions showed good scalability, and excellent ee could still be obtained when the reaction was carried out in gram‐scale.
Products with up to 99 % yield and up to 99 % ee were obtained in aza‐Friedel‐Crafts reaction of 1‐naphthols and electron‐rich phenols with isatin‐derived ketimines using Cu(II) complex bearing binaphthyl‐proline‐imidazoline‐based tridentate chiral ligand as catalyst. The system showed good scalability, and reaction carried out in gram‐scale also provided the desired product in excellent ee.
Sub‐zero amino acid transformation: The cover demonstrates the low temperature conversion of the amino acid l‐tryptophan to the unnatural l‐Kynurenine (Kyn) under a beam of ozone. Kyn is essential to ...the bioactivity of the FDA‐approved, clinically‐used peptide antibiotic Daptomycin (Cubicin) but its unique molecular structure prevents its use in peptide synthesis. The canonical amino acid tryptophan is readily incorporated into the peptide sequence of Daptomycin; under ozonolysis rapid conversion into Kyn realises a novel chemical synthesis of the frontline antibiotic Daptomyin. More information can be found in the Full Paper by P. W. R. Harris, M. A. Brimble, et al. on page 14101.
A chemo‐selective copper(I)‐catalyzed oxytrifluoromethylation of N‐Boc‐ynamides with TMSCF3 has been achieved, affording the trifluoromethylated oxazolones in 51–99% yields. The reaction proceeds at ...room temperature and tolerates a variety of functional groups such as −X, −OMe, alkenyl, and other substituents. The resulting oxazolones provide access to α‐CF3‐substituted amines through decarboxylative reduction.
N,N-Dimethylcarbamoyl(trimethyl)silane reacted with N-Boc-imines in anhydrous benzene under catalysts-free conditions to afford N-Boc-protected α-amino amides in good yields (72–89%). The electronic ...property and the steric hindrance of substituent on the N-Boc-imines affected the reaction.
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