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31.
Robin L. Garrell John C. Smyth Frank R. Fronczek Richard D. Gandour 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(1):73-78
Single crystal X-ray analysis of the 2:1 acetonitrile complex of 18-crown-6 is reported. Crystals of the complex are monoclinic,P21/n, witha=9.123(3),b=8.524(3),c=13.676(4) Å, =104.68(3)°, andD
c
=1.118 g cm–3 forZ=2. The complex lies on a center of symmetry, with the crown in theD
3d conformation. Methyl groups of the acetonitrile molecules have weak interactions with the crown oxygen atoms, and are tilted 31.7° from the host's threefold axis. Methyl hydrogen atoms are rotationally disordered about the acetonitrile axis.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82057 (12 pages). 相似文献
32.
Bedford RB Bruce DW Frost RM Goodby JW Hird M 《Chemical communications (Cambridge, England)》2004,(24):2822-2823
Iron(III) salen and related complexes are active catalysts for the coupling, under mild and simple reaction conditions, of aryl Grignard reagents with primary and secondary alkyl halide substrates bearing beta-hydrogens. 相似文献
33.
The synthesis of the first derivatives of bis(pyrrolo[3,4-d])tetrathiafulvalene has been studied in detail. Starting from the readily available 2,5-dimethylpyrrole (11) and N-phenyl-2,5-dimethylpyrrole, bis(2,5-dimethylpyrrolo[3,4-d])tetrathiafulvalene (8) and the N,N'-disubstituted derivatives 6, 7, 9, and 10 were prepared in good yields by practical procedures. In contrast to the other types of aromatic annelated tetrathiafulvalenes (TTFs), which have appreciably higher oxidation potentials than TTF, the redox behavior of the pyrrolo tetrathiafulvalenes (TTFs) is very close to that of TTF itself. The potential of pyrrolotetrathiafulvalenes as a new series of organic metal building blocks is shown by the two-probe conductivities of the tetracyanoquinodimethane (TCNQ) complexes of the N-phenyl compound 7 and the N-methyl compound 9, which give higher values than TTF-TCNQ under similar conditions. 相似文献
34.
Robin K. Harris Judith A. K. Howard Abdolraouf Samadi-Maybodi Jing Wen Yao Warren Smith 《Journal of solid state chemistry》1995,120(2)
The first crystal structure is reported for a silicate clathrate hydrate involving a triply charged cation [C18H30N3]3+ and an octameric cubic silicate cage. The structure is essentially a host/guest system, with the silicate cages linked into a framework by hydrogen bonding to water molecules. The space group is P
with Z = 2, and the asymmetric unit includes a complete cation and half the anion, plus 21 water molecules (4 of which are in disordered positions). Solid-state (CPMAS) 29Si and 13CNMR spectra are consistent with the diffraction-determined structure and indicate substantial distortion of the anion from cubic symmetry. Solution-state spectra of precursor solutions and of melted material are also presented and discussed. 相似文献
35.
Monwar M Oh SJ Rinaldi PL McCord EF Hutchinson RA Buback MM Latz H 《Analytical and bioanalytical chemistry》2004,378(6):1414-1427
Poly(n-butylacrylate-co-carbon monoxide-co-ethylene) (polyEBC) samples prepared from 13C-labeled monomer, n-butyl acrylate, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex structure of the terpolymer, 2D-1H/13C-heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced resonances in the spectra of two polymer samples, one polymer resulting from synthesis with 1-13C-n-butylacrylate monomer and a second polymer obtained from a synthesis with 2-13C-n-butylacrylate monomer. High-resolution 2D-NMR combined with 13C-labeling of the polymer greatly simplifies the 2D-NMR spectra, selectively enhances the weak peaks from low occurrence B-centered triad structures, and aids in their resonance assignments. In all experiments, the sample temperature was 120 degrees C, to ensure a homogeneous solution and sufficient molecular mobility. Electronic Supplementary Material: Supplementary material (1D 13C NMR spectra of the 13C-labeled and unlabeled polymers) is available in the online version of this article at http://dx.doi.org/100.1007/s00216-003-2402-3. 相似文献
36.
A prenyloxycoumarin from Psiadia dentata 总被引:2,自引:0,他引:2
Fortin H Tomasi S Jaccard P Robin V Boustie J 《Chemical & pharmaceutical bulletin》2001,49(5):619-621
A new coumarin identified as 5-hydroxy-6-methoxy-7-(3-methyl-but-2-enyloxy)-2H-1-benzopyran-2-one (isoobtusitin) was isolated from Psiadia dentata. This compound showed, in vitro, a moderate inhibitory activity against poliovirus and a very weak activity against (HIV), whereas it was inactive against (HSV1), (VSV), and murine tumoral cell lines (3LL, L1210). 相似文献
37.
Prestegane B -the first higher plant occured dibenzyl butanolide lignan with two -phenols- and its dimethylether were isolated from and the structure determinations were performed with the aid of high resolution NMR and Mass fragmentation for the former, and with 2-D J resolved 1H NMR studies and synthesis for the latter. 相似文献
38.
Bivas Mondal Rakesh Maiti Xing Yang Jun Xu Weiyi Tian Jia-Lei Yan Xiangyang Li Yonggui Robin Chi 《Chemical science》2021,12(25):8778
4,5-Dihydropyridazinones bearing an aryl substituent at the C6-position are important motifs in drug molecules. Herein, we developed an efficient protocol to access aryl-dihydropyridazinone molecules via carbene-catalyzed asymmetric annulation between dinucleophilic arylidene hydrazones and bromoenals. Key steps in this reaction include polarity-inversion of aryl aldehyde-derived hydrazones followed by chemo-selective reaction with enal-derived α,β-unsaturated acyl azolium intermediates. The aryl-dihydropyridazinone products accessed by our protocol can be readily transformed into drugs and bioactive molecules.Polarity inversion of arylidene hydrazones to react with bromoenals via carbene organic catalysis is disclosed. The reaction enantioselectively affords 6-aryl-4,5-dihydropyridazinones and related drugs with proven commercial applications. 相似文献
39.
Robin J. Marles James B. Hudson Elizabeth A. Graham Chantal Soucy-Breau Peter Morand R. Lilia Compadre Cesar M. Compadre G. H. Neil Towers J. Thor Arnason 《Photochemistry and photobiology》1992,56(4):479-487
The photoactivated antiviral and cytotoxic activities of the naturally occurring thiophene, alpha-terthienyl (1), and 15 synthetic analogues were evaluated against murine cytomegalovirus and Sindbis virus, and murine mastocytoma cells. After irradiation with near UV light, alpha-terthienyl and most of its analogues had significant toxicity, with minimum inhibitory concentrations in the range of 0.02-40 microM. In the absence of near UV irradiation, only one analogue had antiviral activity and five were cytotoxic. The most active analogues were those containing carboxylic acid, hydroxyl, or cyano substituents. Quantitative structure-activity relationship analysis of thiophene phototoxicity suggested that the rate of singlet oxygen production is the primary determinant of antiviral and cytotoxic activities. For phototoxicity against murine cytomegalovirus, a significant role for hydrophobicity was also demonstrated. Tricyclic thiophenes show significant potential for photochemotherapy of viral infections and cancer, and further evaluation in animal models is recommended. 相似文献
40.