The synthesis of seven novel protected amino acid cavitands is reported. All have four pendant n-undecyl chains and ‘headgroups’ connected by a two-carbon spacer at four positions on the aromatic rings. The amino acids employed are glycine, alanine, phenylalanine, leucine, proline, tryptophan, serine, glutamine and lysine. The structures of the compounds were elucidated using one- and two-dimensional NMR techniques, which verified that all tetra-substituted cavitands have symmetrical C4v conformation. This is the first example of a complete study for amino acid cavitand derivatives. 相似文献
A novel coating method utilizing mechanical alloying was used to deposit a nickel-copper solid solution on the surface of nickel balls in a planetary ball mill. Mechanically milled copper powders were deposited by cold welding on the activated surface of the nickel balls. The impact of the nickel balls causes surface wear, leading to formation of mixed layered particles of copper-nickel and rewelding. In addition, diffusion takes place through the coating layer to form a Ni-Cu solid solution. The hardness of the coating reached a threefold increase (HV0.01594) in comparison with the substrate hardness. Microstructural characterization of the coating surface performed using an optical microscope, SEM, and EPMA indicates that, with appropriate processing conditions, a thick, fully dense coating can be metallurgically bonded to the nickel balls. XRD results revealed the presence of a solid solution and nanocrystalline structure. 相似文献
An efficient three-component synthesis of 6-amino-4-aryl-5-cyano-3-metriyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazoles via a reaction between 3-methyl-1-phenyl-2-pyrazolin-5-one,aromatic aldehydes and malononitrile using tungstate sulfuric acid as a catalyst was described.Mild conditions,good to excellent yields,easily available catalyst and easy work-up are the key features of this method. 相似文献
To understand the effect of a magnetized solvent upon complexation processes between the metal ions and the ligands, we studied the complexation reaction between Y+3 cation with the kryptofix 22DD, in non-magnetized and magnetized methanol solvents at different temperatures using the conductometric method. Addition of kryptofix 22DD to the cation solution causes a continuous increase in the molar conductivities which indicates that the mobility of the complexed cation is higher than the uncomplexed one in both non-magnetized and magnetized methanol solvents. The conductance data show that the stoichiometry of the complex formed between the ligand and Y3+ cation is 1:1(M:L). The value of stability constant of (kryptofix 22DD.Y)3+ complex was determined from conductometric data using a non-linear least-square program (GENPLOT). The results obtained in this investigation, show that the stability constant of the complex decreases when we use magnetized methanol solvent. 相似文献
The large number of emerging antibody-drug conjugates (ADCs) for cancer therapy has resulted in a significant market ‘boom’, garnering worldwide attention. Despite ADCs presenting huge challenges to researchers, particularly regarding the identification of a suitable combination of antibody, linker, and payload, as of September 2021, 11 ADCs have been granted FDA approval, with eight of these approved since 2017 alone. Optimism for this therapeutic approach is clear, despite the COVID-19 pandemic, 2020 was a landmark year for deals and partnerships in the ADC arena, suggesting that there remains significant interest from Big Pharma. Herein we review the enthusiasm for ADCs by focusing on the features of those approved by the FDA, and offer some thoughts as to where the field is headed. 相似文献
A crystal chemistry study of LiNi1 − yCoyO2 phases, used as positive electrode in lithium batteries, is presented. These materials crystallize in the rhombohedral system (space group: R
m) with a layered structure. Rietveld profile refinement of the X-ray data shows that for low substitution amounts ( ≤ 0.20) extra-nickel ions are always present leading to the Li1 − zNi1 + z − tCotO2 (t = y(1 + z)) formula (z * > 0), while for y ≥ 0.30, a pure 2D structure is obtained (z = 0). The stabilization of the 2D character of the structure by cobalt substitution in lithium nickelate leads to the improvement of the electrochemical properties. 相似文献
The role of iron in Na 1.5Fe 0.5Ti 1.5(PO 4)3/C electrode material for Na batteries has been studied by 57Fe Mössbauer spectroscopy in operando mode. The potential profile obtained in the galvanostatic regime shows three plateaus at different voltages due to different reaction mechanisms. Two of them, at 2.2 and 0.3 V vs Na +/Na 0, have been associated to redox processes involving iron and titanium in Na 1.5Fe 0.5Ti 1.5(PO 4)3. The role of titanium was previously elucidated for NaTi 2(PO 4)3 and the effect of the substitution of Fe for Ti was investigated with 57Fe Mössbauer spectroscopy. We show that iron is an electrochemically active center at 2.2 V with the reversible Fe 3+/Fe 2+ transformation and then remains at the oxidation state Fe 2+ along the sodiation until the end of discharge at 0 V. 相似文献
We report on the synthesis of cobalt dihydroxide [Co(OH)2] nanorods and their deposition on a 3-dimensional graphene network via chemical bath deposition. The structural characterization reveals deposited Co(OH)2 to consist of flower-like nanorods on a 3-dimensional graphene foam. The nanocomposite was used for glucose sensing by electrocatalytic oxidation of glucose in 1 M KOH solution. Cyclic voltammetry and amperometric studies revealed a high sensitivity for glucose (3.69 mA mM?1 cm?2) and a 16 nM detection limit. The nanocomposite offers a large effective surface (11.4 cm2) and is very selective for glucose over potentially interfering materials such as dopamine, ascorbic acid, lactose, fructose and urea, not the least due to a relatively low working potential of 0.6 V (vs. Ag/AgCl). The high sensitivity, low detection limit and very good selectivity of free-standing nanocomposite electrodes are attributed to the synergistic effect of (a) the good electrocatalytic activity of the NRs, and (b) the large surface area with high conductivity offered by the 3D graphene foam.
Graphical Abstract Cobalt hydroxide [Co(OH)2] nanorods were deposited on three dimensional graphene (3DG) by a chemical bath deposition method, and the resulting material was used as an electrode for non-enzymatic and specific sensing of glucose in 1 M KOH solution.