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41.
The tetrakis(triphenylphosphine)palladium(O)-catalyzed coupling of benzeneboronic acid with 2-chloro, 6-bromo and 6-bromo-2-chloro derivatives of 1- and 3-methylimidazo[4,5-b]pyridines to novel 2-phenyl-, 6-phenyl- and 2,6-diphenylimidazo[4,5-b]pyridines is described. The phenylation of imidazo[4,5-b]-pyridines containing labile hydrogens was not successful. 相似文献
42.
Mytius californianus exposed for 9 days to a seawater system containing [3H]methylarsonic acid, was found to contain [3H]methylarsonic acid along with [3H]arsenobetaine and two unknown 3H-labeled compounds in the tissue parts of the mussel. A linear increase with time in the specific activity present in the flesh of Mytilus californianus was also observed. The highest specific activity was found in the visceral mass and the gills of the mussel. 相似文献
43.
Dafnis Spiros D. Makri Frosso S. Koutras Markos V. 《Methodology and Computing in Applied Probability》2021,23(1):165-185
Methodology and Computing in Applied Probability - In the present paper we study the distributions of families of patterns which generalize runs and patterns distributions extensively examined in... 相似文献
44.
The novel title compound, a linear isomer of the food mutagen IQ, has been prepared in 67 % yield by Friedländer synthesis from creatinine and 2-aminobenzaldehyde. 相似文献
45.
46.
Guigang Zhang Minghui Liu Tobias Heil Spiros Zafeiratos Aleksandr Savateev Markus Antonietti Xinchen Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15092-15096
Polymeric carbon nitride (PCN) is usually synthesized from nitrogen‐rich monomers such as cyanamide, melamine, and urea, but is rather disordered in many cases. Now, a new allotrope of carbon nitride with internal heterostructures was obtained by co‐condensation of very electron poor monomers (for example, 5‐amino‐tetrazole and nucleobases) in the presence of mild molten salts (for example, NaCl/KCl) to mediate the polymerization kinetics and thus modulate the local structure, charge carrier properties, and most importantly the HOMO and LUMO levels. Results reveal that the as‐prepared NaK‐PHI‐A material shows excellent photo‐redox activities because of a nanometric hetero‐structure which enhances visible light absorption and promotes charge separation in the different domains. 相似文献
47.
Sopasis GJ Canaj AB Philippidis A Siczek M Lis T O'Brien JR Antonakis MM Pergantis SA Milios CJ 《Inorganic chemistry》2012,51(10):5911-5918
Employment of the artificial amino acid 2-amino-isobutyric acid, aibH, in Cu(II) and Cu(II)/Ln(III) chemistry led to the isolation and characterization of 12 new heterometallic heptanuclear [Cu(6)Ln(aib)(6)(OH)(3)(OAc)(3)(NO(3))(3)] complexes consisting of trivalent lanthanide centers within a hexanuclear copper trigonal prism (aibH = 2-amino-butyric acid; Ln = Ce (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10), Tm (11), and Yb (12)). Direct curent magnetic susceptibility studies have been carried out in the 5-300 K range for all complexes, revealing the different nature of the magnetic interactions between the 3d-4f metallic pairs: dominant antiferromagnetic interactions for the majority of the pairs and dominant ferromagnetic interactions for when the lanthanide center is Gd(III) and Dy(III). Furthermore, alternating current magnetic susceptibility studies reveal the possibility of single-molecule magnetism behavior for complexes 7 and 8. Finally, complexes 2, 5-8, 10, and 12 were analyzed using positive ion electrospray mass spectrometry (ES-MS), establishing the structural integrity of the heterometallic heptanuclear cage structure in acetonitrile. 相似文献
48.
We prove global hyperbolicity of spacetimes under generic regularity conditions on the metric. We then show that these spacetimes are timelike and null geodesically complete if the gradient of the lapse and the extrinsic curvature K are integrable. This last condition is required only for the tracefree part of K if the universe is expanding. 相似文献
49.
Rocha TC Oestereich A Demidov DV Hävecker M Zafeiratos S Weinberg G Bukhtiyarov VI Knop-Gericke A Schlögl R 《Physical chemistry chemical physics : PCCP》2012,14(13):4554-4564
We addressed the interaction of oxygen with silver by synchrotron based near ambient pressure X-ray photoelectron spectroscopy at temperatures relevant for industrial oxidation reactions performed with silver catalysts. For silver single crystals, polycrystalline foils and powders in equilibrium with gas phase O(2), we observed the dynamics of the formation of five different atomic oxygen species with relative abundances depending on the temperature and time. Correlation of their formation kinetics with spectroscopic features and thermal stability indicates that these are distinct species with different electronic structures, which might relate to the different roles of silver in oxidation reactions. 相似文献
50.
Meyer FM Collins JC Borin B Bradow J Liras S Limberakis C Mathiowetz AM Philippe L Price D Song K James K 《The Journal of organic chemistry》2012,77(7):3099-3114
A general method for constraining peptide conformations via linkage of aromatic sidechains has been developed. Macrocyclization of suitably functionalized tri-, tetra- and pentapeptides via Suzuki-Miyaura cross-coupling has been used to generate side chain to side chain, biaryl-bridged 14- to 21-membered macrocyclic peptides. Biaryl bridges possessing three different configurations, meta-meta, meta-ortho, and ortho-meta, were systematically explored through regiochemical variation of the aryl halide and aryl boronate coupling partners, allowing fine-tuning of the resultant macrocycle conformation. Suzuki-Miyaura macrocyclizations were successfully achieved both in solution and on solid phase for all three sizes of peptide. This approach constitutes a means of constraining peptide conformation via direct carbogenic fusion of side chains of naturally occurring amino acids such as phenylalanine and tyrosine, and so is complementary to strategies involving non-natural, for example, hydrocarbon, bridges. 相似文献