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41.
Düggeli M Goujon-Ginglinger C Ducotterd SR Mauron D Bonte C von Zelewsky A Stoeckli-Evans H Neels A 《Organic & biomolecular chemistry》2003,1(11):1894-1899
A series of new tetradentate ligands containing two bipyridine groups or two pyridine moieties carrying amine substituents has been synthesised either from 5'- and 6'-substituted chiral bipyridines, or from chiral pyridine derivatives. These precursors have been prepared from (-)-alpha-pinene or (-)-myrtenal, respectively. The structures of three tetradentate-, and of five chiral bipyridine ligands have been determined by X-ray diffraction. 相似文献
42.
Ron S. Dickson Rhonda J. Nesbit Helen Pateras Jennifer M. Patrick Allan H. White 《Journal of organometallic chemistry》1984,265(2):c25-c28
Complexes of formula (η-C5H52Rh2{CF3C2CF3 · RNCO} have been prepared by three methods, from reactions between organic isocyanates and (η-C5H5)2Rh2(CO)(CF3C2CF3) or (η-C5H5)2Rh2(CO)2(CF3C2CF3); by treatment of (η-C5H5)2Rh2(CO)(CF3C2CF3) with organic azides; and by oxidation with Me3NO of the organic isocyanide in (η-C5H5)2Rh2(CO)(CNR)(CF3C2CF3). The crystal and molecular structure of the complex (η-C5H5)2Rh2{CF3C2CF3 · RNCO} with R = Ph has been determined from single crystal X-ray diffraction data. This reveals that the isocyanate has condensed with the hexafluorobut-2-yne to form an amide ligand of the form C(CF3)C(CF3)C(=O)N(R); this bridges the two rhodium atoms in a μ2η3-manner. 相似文献
43.
McSparron H Blythe MJ Zygouri C Doytchinova IA Flower DR 《Journal of chemical information and computer sciences》2003,43(4):1276-1287
JenPep is a relational database containing a compendium of thermodynamic binding data for the interaction of peptides with a range of important immunological molecules: the major histocompatibility complex, TAP transporter, and T cell receptor. The database also includes annotated lists of B cell and T cell epitopes. Version 2.0 of the database is implemented in a bespoke postgreSQL database system and is fully searchable online via a perl/HTML interface (URL: http://www.jenner.ac.uk/JenPep). 相似文献
44.
Spring DR Krishnan S Blackwell HE Schreiber SL 《Journal of the American Chemical Society》2002,124(7):1354-1363
Diversity-oriented synthesis of structurally complex and diverse small molecules can be used as the first step in a process to explore cellular and organismal pathways. The success of this process is likely going to be dependent on advances in the synthesis of small molecules having natural product-like structures in an efficient and stereoselective manner. The development, scope, and mechanism of the oxidation of organocuprates was investigated and exploited in the atropdiastereoselective synthesis of biaryl-containing medium rings (9-, 10-, and 11-membered rings). The methodology was performed on high-capacity, large polystyrene beads by metalating aryl bromides with i-PrBu(2)MgLi, followed by transmetalating with CuCN x 2LiBr and then oxidizing with 1,3-dinitrobenzene, and was used in a diversity-oriented synthesis of biaryl-containing medium rings (library total theoretical maximum 1412 members). The high capacity beads were arrayed into 384-well plates and, using a process optimized during the development of a one bead/one stock solution technology platform, converted into arrays of stock solutions, with each stock solution containing largely one compound. These stock solutions were used in numerous phenotypic and protein-binding assays. The process described outlines a pathway that we feel will contribute to a comprehensive and systematic chemical approach to exploring biology (chemical genetics). 相似文献
45.
Coronado E Gómez-García CJ Nuez A Romero FM Rusanov E Stoeckli-Evans H 《Inorganic chemistry》2002,41(18):4615-4617
The combination of hexacyanoferrate(III) anions, [Fe(CN)(6)](3)(-), with nickel(II) complexes derived from the chiral ligand trans-cyclohexane-1,2-diamine (trans-chxn) affords the enantiopure layered compounds [Ni(trans-(1S,2S)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (1) and [Ni(trans-(1R,2R)-chxn)(2)](3)[Fe(CN)(6)](2).2H(2)O (2). These chiral systems behave as ferromagnets (T(c) = 13.8 K) with a relatively high coercive field (H(c) = 0.17 T) at 2 K. They also exhibit an unusual magnetic behavior at low temperatures that has been attributed to the dynamics of the magnetic domains in the ordered phase. 相似文献
46.
Chifotides HT Koshlap KM Pérez LM Dunbar KR 《Journal of the American Chemical Society》2003,125(35):10703-10713
The N7/O6 equatorial binding interactions of the antitumor active complex Rh(2)(OAc)(4)(H(2)O)(2) (OAc(-) = CH(3)CO(2)(-)) with the DNA fragment d(GpG) have been unambiguously determined by NMR spectroscopy. Previous X-ray crystallographic determinations of the head-to-head (HH) and head-to-tail (HT) adducts of dirhodium tetraacetate with 9-ethylguanine (9-EtGH) revealed unprecedented bridging N7/O6 guanine nucleobases that span the Rh-Rh bond. The absence of N7 protonation at low pH and the notable increase in the acidity of N1-H (pK(a) approximately 5.7 as compared to 8.5 for N7 only bound platinum adducts), suggested by the pH dependence titrations of the purine H8 (1)H NMR resonances for Rh(2)(OAc)(2)(9-EtG)(2) and Rh(2)(OAc)(2-)[d(GpG)],are consistent with bidentate N7/O6 binding of the guanine nucleobases. The pK(a) values estimated for N1-H (de)protonation, from the pH dependence studies of the C6 and C2 (13)C NMR resonances for the Rh(2)(OAc)(2)(9-EtG)(2) isomers, concur with those derived from the H8 (1)H NMR resonance titrations. Comparison of the (13)C NMR resonances of C6 and C2 for the dirhodium adducts Rh(2)(OAc)(2)(9-EtG)(2) and Rh(2)(OAc)(2)[d(GpG)] with the corresponding resonances of the unbound ligands [at pH 7.0 for 9-EtGH and pH 8.0 for d(GpG)], shows substantial downfield shifts of Deltadelta approximately 11.0 and 6.0 ppm for C6 and C2, respectively; the latter shifts reflect the effect of O6 binding to the dirhodium centers and the ensuing enhancement in the acidity of N1-H. Intense H8/H8 ROE cross-peaks in the 2D ROESY NMR spectrum of Rh(2)(OAc)(2)[d(GpG)] indicate head-to-head arrangement of the guanine bases. The Rh(2)(OAc)(2)[d(GpG)] adduct exhibits two major right-handed conformers, HH1 R and HH2 R, with HH1 R being three times more abundant than the unusual HH2 R. Complete characterization of both adducts revealed repuckering of the 5'-G sugar rings to C3'-endo (N-type), retention of C2'-endo (S-type) conformation for the 3'-G sugar rings, and anti orientation with respect to the glycosyl bonds. The structural features obtained for Rh(2)(OAc)(2))[d(GpG)] by means of NMR spectroscopy are very similar to those for cis-[Pt(NH(3))(2))[d(GpG)]] and corroborate molecular modeling studies. 相似文献
47.
Gianini M Forster A Haag P von Zelewsky A Stoeckli-Evans H 《Inorganic chemistry》1996,35(17):4889-4895
cis-Bis-homoleptic platinum(II) complexes, with predetermined helical chirality at the metal center, can be obtained by using strongly sterically interacting ligands. With this aim, two new ligands, (8R,10R)-2-(2'-thienyl)-4,5-pinenopyridine, th4,5ppy (2), and (8R,10R)-2-(2'-thienyl)-5,6-pinenopyridine, th5,6ppy (4), were synthesized and coordinated to platinum. The structures of the resulting complexes, Pt(th4,5ppy)(2) (5) and Pt(th5,6ppy)(2) (6), were determined by X-ray diffraction, and it was found that they both crystallize with a Delta-cis configuration. Thermal oxidative additions (TOA) of alkyl halides were performed with both complexes leading, in the case of 5, to a mixture of isomers and, in the case of 6, to isomerically pure products. The predetermination of chirality at the metal center is therefore preserved in the octahedral (OC-6) platinum(IV) complexes. Crystals of Pt(th4,5ppy)(2) (5) are orthorhombic, of space group P2(1)2(1)2(1), with a = 12.973(1) ?, b = 13.619(2) ?, c = 17.665(2) ?, alpha = beta = gamma = 90 degrees, and Z = 4. Final R = 0.0268 and R(w) = 0.0424 for 3101 observed reflections. Crystals of Pt(th5,6ppy)(2) (6) are hexagonal, of space group P6(1), with a = 11.5465(4) ?, b = 11.5465(4) ?, c = 35.356(3) ?, alpha = beta = 90 degrees, gamma = 120 degrees, and Z = 6. Final R = 0.0424 and R(w) = 0.0845 for 2660 observed reflections. Neither molecule possesses a crystallographic C(2) symmetry. 相似文献
48.
Following the strategy of using polyfunctional phosphonic acids for the synthesis of open-framework metal phosphonates, the phosphonocarboxylic acid (H2O3PCH2)2NCH2C6H4COOH was used in the hydrothermal synthesis of new Ba phosphonates. Its decomposition led to the first open-framework barium phosphonate [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O. The synthesis was also successfully performed using iminobis(methylphosphonic acid), (H2O3PCH2)2NH, as a starting material, and the synthesis was optimized to obtain as a pure material. The reaction setup as well as the pH are the dominant parameters, and only a diffusion-controlled reaction led to the desired compound. The crystal structure was solved from single-crystal data: monoclinic; C2/c; a=2328.7(2), b=1359.95(7), and c=718.62(6) pm; beta=98.732(10) degrees ; V=2249.5(3)x10(6) pm3; Z=4; R1=0.036; and wR2=0.072 (all data). The structure of [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O is built up from BaO8 and BaO10 polyhedra forming BaO chains and layers, respectively. These are connected to a three-dimensional metal-oxygen-metal framework with the iminobis(methylphosphonic acid) formally coating the inner walls of the pores. The one-dimensional pores (3.6x4 A) are filled with H2O molecules that can be thermally removed. Thermogravimetric investigations and temperature-dependent X-ray powder diffraction demonstrate the stability of the crystal structure up to 240 degrees C. The uptake of N,N-dimethylformamide and H2O by dehydrated samples is demonstrated. Furthermore, IR, Raman, and 31P magic-angle-spinning NMR data are also presented. 相似文献
49.
50.
Niamh NicDaéid Saravana Jayamana William J. Kerr Wolfram Meier-Augenstein Helen F. Kemp 《Analytical and bioanalytical chemistry》2013,405(9):2931-2941
A number of methods of clandestine manufacture of methylamphetamine involve the extraction and subsequent reaction of pseudoephedrine hydrochloride with other essential chemicals. The precursor can be easily extracted from over-the-counter medication widely available in the UK and elsewhere. Essential chemicals such as iodine and red phosphorous are also readily available and can be extracted from iodine tinctures and matchboxes, respectively. This work reports the repetitive preparation of methylamphetamine using two popular routes (the Moscow and Hypophosphorous synthesis). The focus was on the extraction solvent used for isolation of the precursor chemical and any consequential isotopic variation which may arise in the final product. Six batches of methylamphetamine were prepared under precisely controlled conditions for each synthetic route and for each of three different precursor extraction solvents. Synthesis of the final product from laboratory grade precursor using the synthetic methods described was used as a template for comparison. The resultant IRMS data from all 48 prepared samples suggests some underlying trends in the identification of the synthetic route which may aid in the interpretation of IRMS data derived from clandestine samples. 相似文献