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61.
The synthesis of a new trifluoromethyl 2-mercapto-1,3-thiadiazole derivative from 5,5,5-trifluoro-4-(trifluoromethyl)-3-penten-2-one, its structural study in the solid state and in the liquid phase and the thiol-thione tautomeric equilibrium study of the title compound are reported. The crystalline structure shows short intermolecular FF contacts. Theoretical calculations using HF and DFT methods were performed. Vibrational spectra were calculated for both tautomers and compared with experimental data. The experimental and theoretical results can be interpreted in terms of the existence of a thione tautomer in the solid and in solution. 相似文献
62.
Dr. Alexander G. Harter Prof. Dr. Thomas M. Klapötke Dr. Burkhard Krumm Jasmin T. Lechner Christian Riedelsheimer 《European journal of organic chemistry》2023,26(24):e202300302
Two new bridged nitraminotriazoles with bridging oxapropylene and nitrazapropylene moieties were synthesized, and converted into several salts, as well as from the hydrazonemethylene bridged nitraminotriazole. All compounds were fully characterized by NMR and IR spectroscopy, elemental analysis as well as differential thermal analysis. The sensitivity towards friction and impact were determined according to BAM standard technics and the energetic properties were calculated by using the EXPLO5 computer code. The neutral compounds as well as the various salts were examined in terms of their physicochemical properties and detonation performance to each other and compared to the commonly used secondary explosive RDX. 相似文献
63.
Karl Cammann Udo Lemke Anja Rohen Jürgen Sander Hildegard Wilken Babette Winter 《Angewandte Chemie (International ed. in English)》1991,30(5):516-539
Chemical and environmental engineering and biotechnology are among the fields now being transformed by continually increasing levels of automation. Whereas the objective in other sectors of industry is simply to increase efficiency, here considerations of system theory or safety demand a high level of automation. Either the processes are too complex and require multifunctional control with feedback, or an analysis of the safety requirements shows the necessity for a certain degree of redundancy in the safety measures, and for elimination of human error as a risk factor. With regard to quality control, cost-benefit analyses lead to striking conclusions which again indicate the need for highly automated, and above all reliable, systems to eliminate rejects. The crux of any automated system is the measurement and control technology; of central importance is the rapid, reliable, and in some cases continuous, measurement and interpretation of key processes or control variables. For this purpose a wide variety of recording instruments and sensors are used to give as accurate a picture as possible of the state of the system. It is obvious from this that the performance of the control system is critically dependent on the sensors. Errors in the measured quantities can become amplified in the control variables or, in dynamic systems, can lead to undesirable operating conditions. Moreover, as a consequence of great advances in microelectronics, “intelligent sensors” which can calibrate and control themselves will be one of the key technologies of the nineties. Unless fast and immediate information on the true current status of a system is available, microprocessors as control devices react blindly and unpredictably to errors in input information. New discoveries in the fields of electronic, electrochemical, and optical transducers are now being applied in heterogeneous catalysis and surface physics, and in biochemistry (enzymology and immunology); in these fields new chemical sensor principles are being tested, which could revolutionize instrumental methods of molecular analysis in particular, owing to their very favorable cost-performance relationship. This article aims to give an up-to-date overview of the current state of the art in these developments, with emphasis on their importance for analysis and their significance in relation to the chemist's interest in mechanisms for identifying substances. 相似文献
64.
Dr. Samuel M. Meier M. Sc. Dominique Kreutz Dr. Lilli Winter M. Sc. Matthias H. M. Klose M. Sc. Klaudia Cseh M. Sc. Tamara Weiss Dr. Andrea Bileck M. Sc. Beatrix Alte Dr. Johanna C. Mader M. Sc. Samir Jana Dr. Annesha Chatterjee Dr. Arindam Bhattacharyya Michaela Hejl Dr. Michael A. Jakupec Priv.-Doz. Dr. Petra Heffeter Prof. Dr. Walter Berger Prof. Dr. Christian G. Hartinger Prof. Dr. Bernhard K. Keppler Prof. Dr. Gerhard Wiche Prof. Dr. Christopher Gerner 《Angewandte Chemie (International ed. in English)》2017,56(28):8267-8271
Organometallic metal(arene) anticancer agents require ligand exchange for their anticancer activity and this is generally believed to confer low selectivity for potential cellular targets. However, using an integrated proteomics-based target-response profiling approach as a potent hypothesis-generating procedure, we found an unexpected target selectivity of a ruthenium(arene) pyridinecarbothioamide (plecstatin) for plectin, a scaffold protein and cytolinker, which was validated in a plectin knock-out model in vitro. Plectin targeting shows potential as a strategy to inhibit tumor invasiveness as shown in cultured tumor spheroids while oral administration of plecstatin-1 to mice reduces tumor growth more efficiently in the invasive B16 melanoma than in the CT26 colon tumor model. 相似文献
65.
66.
The EPR single-crystal and powder spectra of mixed crystals of (3-chloroanilinium)(8)(Cd(1-x)Cu(x)Cl(6))Cl(4) are measured as a function of temperature and x and analyzed with respect to the geometry and bonding properties of the CuCl(6) polyhedra. These undergo strong distortions due to vibronic Jahn-Teller coupling, with the resulting tetragonal elongation being superimposed by a considerable orthorhombic symmetry component induced by a host site strain acting as a compression along the crystallographic a axis. This strain becomes apparent in the cadmium compound (x = 0), whose crystal structure is also reported [a = 8.701(2) ?, b = 13.975(2) ?, c = 14.173(2) ?, alpha = 81.62(1) degrees, beta = 72.92(1) degrees, gamma = 77.57(1) degrees, triclinic P&onemacr;, Z = 1]. A calculation of the ground state potential surface and its vibronic structure nicely reproduces the g values, Cu-Cl spacings, and ligand field data. At high copper concentrations (including x = 1), the CuCl(6) polyhedra are coupled elastically, with the long axes of neighboring polyhedra having perpendicular orientations. The elastic correlation presumably is not of the long-range antiferrodistortive type, however. Above about 55 K, the angular Jahn-Teller distortion component becomes dynamically averaged within the time scale of the EPR experiment, leading to local tetragonally compressed CuCl(6) octahedra. 相似文献
67.
Synthesis of 2′-Deoxy-5-(isothiazol-5-yl)uridine and Its Interaction with the HSV-1 Thymidine Kinase
Ingrid Luyten Hans De Winter Roger Busson Theo Lescrinier Isabelle Creuven Franlois Durant Jan Balzarini Erik De Clercq Piet Herdewijn 《Helvetica chimica acta》1996,79(5):1462-1474
2′-Deoxy-5-(isothiazol-5-yl)uridine ( 12 ) was synthesized starting from 2′-deoxy-5-iodouridine using a Pd-catalysed cross-coupling reaction with propiolaldehyde diethyl acetal followed by deprotection and ring closure using thiosulfate. 2′-Deoxyuridine 12 has a particular place among the 5-heteroaryl-substituted 2′-deoxyuridines in that it has a high affinity for herpes simplex virus type 1 (HSV-1)-encoded thymidine kinase (TK) without antiviral activity. Biochemical studies revealed that 12 is a substrate for viral TK. We further investigated the interaction of 12 with the HSV-1 thymidine kinase. The conformation of 12 in solution was established by NMR spectroscopy. The most stable conformer 12A has the S-atom of the isothiazole ring placed in the neighbourhood of the C(4)?O group of the pyrimidine moiety. The compound was docked in its most stable conformation in the active site of HSV-1 TK and subjected to energy minimization. This demonstrated that the isothiazole moiety binds in a cavity lined by the side chains of Tyr-132, Arg-163, Ala-167, and Ala-168 and that the C(3) atom of the isothiazole moiety is located in close proximity of the phenolic O-atom of Tyr-132 and the aliphatic part of the Arg-163 side chain. 相似文献
68.
H. Binder R. Kellner K. Vaas M. Hein F. Baumann M. Wanner R. Winter W. Kaim W. Hnle Y. Grin U. Wedig M. Schultheiss R. K. Kremer H. G. von Schnering O. Groeger G. Engelhardt 《无机化学与普通化学杂志》1999,625(7):1059-1072
Halogenation of nido-B10H14 with C2H2Cl4, C2Cl6, Br2, or I2, produces by cluster degradation the (2 n)-closo-clusters B9X9 (X = Cl, Br, I). The synthesis of salts of the perhalogenated radical anions of the type (2 n + 1)-closo-[B9X9]· – and of the corresponding dianions (2 n + 2)-closo-[B9X9]2– from neutral B9X9 is described [n is the number of cluster atoms; (2 n), (2 n + 1), and (2 n + 2) is the number of cluster electrons]. Molecular and crystal structures of B9Cl9, B9Br9, [(C6H5)4P][B9Br9] · CH2Cl2, and [(C4H9)4N]2[B9Br9] · CH2Cl2 have been determined via X-ray diffraction. All three oxidation states of the cluster retain the tricapped trigonal prism. The reduction of the clusters B9X9 was shown by cyclic voltammetry in CH2Cl2 to proceed via two successive one-electron reversible steps, separated by at least 0.4 V. The paramagnetic radical anions [B9X9]· – (X = Cl, Br) were further characterized by magnetic susceptibility measurements of [Cp2Fe][B9X9] and [Cp2Co][B9X9], respectively. The EPR spectra of [B9X9]· – (X = Cl, Br, I) in glassy frozen CH2Cl2 solutions showed increasing g anisotropy for the heavier halogen derivatives, illustrating significant halogen participation at the singly occupied MO. The 11B NMR spectra of CD2Cl2 solutions of the neutral clusters B9X9 exhibit only one sharp resonance, indicating that the boron atoms are highly fluxional in solution. In contrast, two different boron resonances as expected for a rigid tricapped trigonal prism are clearly observed for the [B9X9]2– dianions in solutions and for solid B9Br9 in the 11B MAS NMR spectra. Temperature dependent 11B MAS NMR experiments on B9Br9 and [B9Br9]2– in the solid state show a reversible coalescence of the two resonances at higher temperature. 11B MAS NMR spectra and DTA measurements of [B9Br9]2– showed a phase transition. 相似文献
69.
Heiko Schirmer Michael Duetsch Frank Stein Thomas Labahn Burkhard Knieriem Armin de Meijere 《Angewandte Chemie (International ed. in English)》1999,38(9):1285-1287
A novel mode of reaction towards arylethynes is shown by the β-trimethylsilyl-substituted α,β-unsaturated Fischer carbene complexes 1 . A mixture of the isomeric, highly substituted spiro[4.4]nonatrienes 2 and 3 is formed by the formal insertion of three alkyne molecules and subsequent cyclization (see scheme). Such selective triple insertions of alkynes into ethenylcarbene complexes have not been previously observed. 相似文献
70.
Dr. Leyre Marzo Dr. Santosh K. Pagire Prof. Dr. Oliver Reiser Prof. Dr. Burkhard König 《Angewandte Chemie (International ed. in English)》2018,57(32):10034-10072
Visible‐light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross‐coupling reactions, α‐amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible‐light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible‐light‐absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo‐ or metal catalysis. 相似文献