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11.
Summary Manganese(II) complexes of bis(2-benzimidazolylmethyl) ether (DGB), bis(2-benzimidazolylmethyl) sulphide (TGB) and the n-butyl derivative of DGB (BDGB) were prepared and characterised. The solution e.p.r. spectrum of [Mn(TGB)Cl2] in DMF at 143 K is commensurate with an axially distorted monomeric manganese(II) complex, room temperature magnetic moment
(6.04 B.M.) per manganese(II) atom being in the range found for other d5 monomeric manganese(II) complexes. The solution e.p.r. spectrum of [Mn(BDGB)Cl2]-2H2O in DMF at 143 K indicates the presence of two equivalent manganese(II) ions coupled by an exchange interaction, fostered
by bridging chlorides. Evidence for this is provided by a nearly isotropic 11 line hyperfine structure of 55Mn, with a coupling constant 45 ± 5G. Contact-shifted 1H n.m.r. data also supports an exchange coupled dimeric manganese complex. The room temperature magnetic moment, 5.64 B.M.,
per manganese(II) indicates quenching of the magnetic moment below that of monomeric manganese(II) ion. The [Mn(DGB)Cl2]·H2O complex exhibits a magnetic moment of 6.02 B.M. per manganese, indicating a monomeric manganese complex. E.p.r. data of
the complex diluted in an analogous Zn-DGB complex (1∶20) correlates well for D = 0.22cm−1 and λ ∼- 0.267. The [Mn(DGB)-(C1O4)2] and [Mn(BDGB)(ClO4)2] complexes, diluted in analogous Zn-DGB and Zn-BDGB complexes (1∶20), show a strong single e.p.r. line at g
eff ∼- 2. The complexes have low magnetic moments; 4.44 B.M./Mn and 4.39 B.M./Mn, at room temperature. 相似文献
12.
Gita Subba Rao R. S. Tyagi R. K. Mishra 《International journal of quantum chemistry》1981,20(1):273-279
The conformational energy of acetylcholine is minimized with respect to the distances between nonbonded atoms with the help of the Bremermann method of unconstrained global optimization. The set of distances for which the energy is the absolute minimum is then used to calculate the coordinates of all the atoms and hence the conformation of the molecule. The simplest type of potential function, namely the classical potential function is chosen for the calculation. The major advantages of this method are (i) that the starting point need not be close to the actual solution, (ii) that it gives the global minimum, irrespective of the starting point, (iii) that it is very general and can be used for any type of potential function, and (iv) that it does not require the computation of gradients. The results obtained are in very good agreement with those of other workers. 相似文献
13.
A relatively mild, efficient, and inexpensive method for the nucleophilic aromatic substitution of the N–H heterocycles with various aryl and heteroaryl iodides using copper nanoparticles (Cu-NP) is reported. The coupling reaction has been successfully achieved with moderate to good yields. 相似文献
14.
K. Soni M. K. Samota P. Jhajharia Gita Seth 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2845-2853
Novel organophosphorus compounds have been conveniently prepared using 2-(2′-hydroxynapthyl)benzoxazole and 2-(2′-aminophenyl)benzoxazole as starting materials. Phosphorylation and thiophosphorylation was performed using different molar ratio (1:1, 1:2 and 1:3) of phosphorus oxychloride/thiophosphoryl chloride and substituted benzoxazole. The toxicity of newly synthesized phosphorylated/thiophosphorylated compounds was tested on Aspergillus niger and Fusarium oxysporium. All were found antifungal agents. Plausible structures have been proposed on the basis of IR, 1 H NMR, 31 P NMR spectral studies. 相似文献
15.
Priyanka Jhajharia Mahesh Kumar Samota Gita Seth 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1361-1368
Abstract A series of biologically active phenoxy derivatives of 2-substituted benzoxazole organophosphates have been synthesized by the reaction of O-(naphthyl benzoxazolyl-2-) phosphorodichloridate/phosphorodichloridothioate with phenol/4-chlorophenol/4-nitroph- enol in 1:1 and 1:2 molar ratios. These compounds have been characterized on the basis of elemental analysis, IR, 1H NMR, 31P NMR, and mass spectral studies. The antibacterial activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (?ve). The antifungal activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. All compounds were found to have significant antibacterial and antifungal activity. 相似文献
16.
The tachykinin receptor NK? is a member of the rhodopsin family of G-protein coupled receptors. The NK? receptor has been regarded as an important drug target due to diverse physiological functions and its possible role in the pathophysiology of psychiatric disorders, including schizophrenia. The NK3 receptor is primarily activated by the tachykinin peptide hormone neurokinin B (NKB) which is the most potent natural agonist for the NK? receptor. NKB has been reported to play a vital role in the normal human reproduction pathway and in potentially life threatening diseases such as pre-eclampsia and as a neuroprotective agent in the case of neurodegenerative diseases. Agonist binding to the receptor is a critical event in initiating signaling, and therefore a characterization of the structural features of the agonists can reveal the molecular basis of receptor activation and help in rational design of novel therapeutics. In this study a molecular model for the interaction of the primary ligand NKB with its G-protein coupled receptor NK? has been developed. A three-dimensional model for the NK? receptor has been generated by homology modeling using rhodopsin as a template. A knowledge based docking of the NMR derived bioactive conformation of NKB to the receptor has been performed utilizing limited ligand binding data obtained from photoaffinity labeling and site-directed mutagenesis studies. A molecular model for the NKB-NK? receptor complex obtained sheds light on the topographical features of the binding pocket of the receptor and provides insight into the biochemical data currently available for the receptor. 相似文献
17.
The reaction of phosphorus oxychlo‐ ride/phosphorus thiochloride with 2‐(2′‐mercapto‐ phenyl)benzoxazole in 1:1, 1:2, and 1:3 molar ratio in the presence of stoichiometric amounts of triethyl‐ amine has afforded a series of organophosphates. These organophosphates have been characterized by elemental analyses, infrared, 1H NMR, 31P NMR, and mass spectral studies. The antifungal activity of these organophosphates has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. The antifungal screening data reveal that these compounds are more fungitoxic than 2‐(2′‐mercaptophenyl) benzoxazole. These organophosphates were also found to be insecticidal when tested against Periplenata americana.© 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:309–315, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20551 相似文献
18.
Gita Subba Rao R. S. Tyagi R. K. Mishra 《International journal of quantum chemistry》1986,29(5):1177-1180
The preferred conformations of the thyrotropin-releasing hormone (TRH) have been calculated by the global optimization method proposed earlier by us. [G. Subba Rao, R. S. Tyagi, and R. K. Mishra, J. Theor. Biol. 90 , 377 (1981)]. The potential function used comprises the electrostatic, nonbonded, torsional and hydrogen-bonding terms. The results are in good agreement with the crystal structures of TRH. No intramolecular hydrogen bonding is found to occur. 相似文献
19.
People,Places, Things: Web Presence for the Real World 总被引:2,自引:1,他引:1
Kindberg Tim Barton John Morgan Jeff Becker Gene Caswell Debbie Debaty Philippe Gopal Gita Frid Marcos Krishnan Venky Morris Howard Schettino John Serra Bill Spasojevic Mirjana 《Mobile Networks and Applications》2002,7(5):365-376
The convergence of Web technology, wireless networks, and portable client devices provides new design opportunities for computer/communications systems. In the HP Labs' Cooltown project we have been exploring these opportunities through an infrastructure to support web presence for people, places and things. We put web servers into things like printers and put information into web servers about things like artwork; we group physically related things into places embodied in web servers. Using URLs for addressing, physical URL beaconing and sensing of URLs for discovery, and localized web servers for directories, we can create a location-aware but ubiquitous system to support nomadic users. On top of this infrastructure we can leverage Internet connectivity to support communications services. Web presence bridges the World Wide Web and the physical world we inhabit, providing a model for supporting nomadic users without a central control point. 相似文献
20.
A separable representation for the off-shell two-body t-matrix for a local Hulthén potential is presented, in which deuteron states are chosen as the expansion bases. Using the Faddeev equations with these t-matrices as input, the ground state energy of the triton and doublet and quartet scattering lengths in neutron-deuteron scattering, have been computed. The results have been compared with the experimental findings and the theoretical results of Sitenko et al. obtained in the Sturmian function representation with the same Hulthén potential. 相似文献