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531.
Iwona Tomaszkiewicz 《Thermochimica Acta》2004,420(1-2):33-36
Studies by fluorine bomb calorimetry that lead to the evaluation of thermodynamic properties of group-III nitrides are described. Results of the studies of the standard molar enthalpy of formation ΔfHm0 of two BN polymorphic forms and initial experiments on the combustion of GaN are presented. 相似文献
532.
Badis M Tomaszkiewicz I Joly JP Rogalska E 《Langmuir : the ACS journal of surfaces and colloids》2004,20(15):6259-6267
Four new chiral, amphiphilic crown ethers differing by the hydrophobic tailgroups were synthesized, and their capacity to recognize enantiomeric amino acids was examined using Langmuir films. Surface pressure and surface potential measurements performed on the subphases containing L or D enantiomers of alanine, valine, phenylglycine, and tryptophane indicate that the crown ethers forming the monolayer interact with the amino acids. The effects observed are ascribed to the formation of host-guest complexes. The differences in the magnitude of the effects measured show that the crown ethers are capable of discriminating between different amino acids as well as the enantiomers. Our results demonstrate that the structure of the monolayer plays a decisive role in the molecular recognition process including chiral recognition. 相似文献
533.
Hajduk PJ Mack JC Olejniczak ET Park C Dandliker PJ Beutel BA 《Journal of the American Chemical Society》2004,126(8):2390-2398
An NMR-based alternative to traditional X-ray crystallography and NMR methods for structure-based drug design is described that enables the structure determination of ligands complexed to virtually any biomolecular target regardless of size, composition, or oligomeric state. The method utilizes saturation transfer difference (STD) NMR spectroscopy performed on a ligand complexed to a series of target samples that have been deuterated everywhere except for specific amino acid types. In this way, the amino acid composition of the ligand-binding site can be defined, and, given the three-dimensional structure of the protein target, the three-dimensional structure of the protein-ligand complex can be determined. Unlike earlier NMR methods for solving the structures of protein-ligand complexes, no protein resonance assignments are necessary. Thus, the approach has broad potential applications--especially in cases where X-ray crystallography and traditional NMR methods have failed to produce structural data. The method is called SOS-NMR for structural information using Overhauser effects and selective labeling and is validated on two protein-ligand complexes: FKBP complexed to 2-(3'-pyridyl)-benzimidazole and MurA complexed to uridine diphosphate N-acetylglucosamine. 相似文献
534.
Matejícek P Cígler P Olejniczak AB Andrysiak A Wojtczak B Prochazka K Lesnikowski ZJ 《Langmuir : the ACS journal of surfaces and colloids》2008,24(6):2625-2630
We report the first evidence that boron-containing nucleoside conjugates have a tendency to associate in water solutions. The size, charge, and exoskeletal pattern of the boron cluster can strongly influence the aggregation. The aggregation of nucleosides with attached boron clusters was observed using light scattering and atomic force microscopy techniques. Although the species containing either the bulky amphiphilic [3-cobalt(III) bis(1,2-dicarbollide)]- anion or the electroneutral dicarba-closo-dodecaboranyl moiety tend to form stable nanoparticles in aqueous solutions, the compounds bearing the smaller, negatively charged dicarba-nido-undecaboranyl moiety as well as the unmodified nucleosides do not aggregate. The light scattering measurements also showed that the aggregated species can interact with nonionic surfactant Triton X-100 in solution. The partition coefficients P in the water-octanol system correlate fairly well with the aggregation tendency observed by light scattering measurements. This finding allows us to predict the association behavior of boron-cluster-containing nucleosides on a qualitative level. The observed phenomenon can contribute to a better understanding of biological properties of boronated nucleosides and the design of boronated nucleoside-based drugs such as boron carriers for boron neutron capture therapy of tumors (BNCT) and antiviral agents. 相似文献
535.
Iwona Dams Michał Chodyński Małgorzata Krupa Anita Pietraszek Marta Zezula Piotr Cmoch Monika Kosińska Andrzej Kutner 《Tetrahedron》2013,69(5):1634-1648
The 16-(3-trifluoromethyl)phenoxy PGF2α analogue travoprost (8a) has potent topical ocular activity. A novel convergent synthesis of 13,14-en-15-ol PGF2α analogues was developed employing Julia–Lythgoe olefination of the structurally advanced prostaglandin phenylsulfone (5Z)-(+)-15 with a new enantiomerically pure aldehyde ω-chain synthon (S)-(?)-16a. Subsequent hydrolysis of protecting groups and final esterification of fluprostenol (7a) yielded travoprost (8a). The main advantages are the preparation of high purity travoprost (8a) and the application of comparatively cheap reagents. The novel convergent strategy allows the synthesis of a whole series of 13,14-en-15-ol PGF2α analogues from a common and structurally advanced prostaglandin intermediate 15. The preparation and identification of two synthetic impurities, 15-epi isomer (8b) of travoprost and a new prostaglandin related ester (5Z)-(+)-18, are also described. 相似文献
536.
Prochowicz D Justyniak I Kornowicz A Kaczorowski T Kaszkur Z Lewiński J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(24):7367-7371
The polymer network: The reaction of quinine (QN) with CuI under solvothermal, as well as liquid-assisted grinding, conditions afforded a unique 1D homochiral coordination polymer {[Cu(4)(μ(3)-I)(4)(QN)(2)][Cu(3)(μ(3)-I)(2)(μ(2)-I)(QN)(2)](2)}(n), containing both triangular Cu(3)I(3) and cubane Cu(4)I(4) clusters as connecting nodes (see scheme). Van der Waals interactions between the adjacent 1D polymer chains lead to an extended quasi-honeycomb homochiral pillared 3D network with solvent-free 1D channels. 相似文献
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539.
Back Cover: A Supramolecular Photosynthetic Model Made of a Multiporphyrinic Array Constructed around a C60 Core and a C60–Imidazole Derivative (Chem. Eur. J. 1/2014) 下载免费PDF全文
540.