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91.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong‐Kun Fun A. Sreekanth S. Sivakumar M. R. Prathapachandra Kurup 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):m461-m463
One half of the molecule of the title complex, [Mn(C14H13N4S)2], is related to the other half by a twofold axis passing through the Mn atom. This high‐spin Mn atom is six‐coordinated, in an octahedral geometry, by the azomethine N, the pyridyl N and the thiolate S atom of two planar 1‐(pyridin‐2‐yl)ethanone N(4)‐phenylthiosemicarbazone ligands. In the crystal, the molecules are interconnected by N—H?S and C—H?N interactions, forming a three‐dimensional network. 相似文献
92.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o477-o479
In the title compounds, C24H17NO3, (I), and C43H27NO5, (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in molecule (I) but is essentially planar in molecule (II). The configuration of the dioxine–oxazoline system is determined by the sp3 state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent molecules related by a pseudo‐inversion centre. 相似文献
93.
Hoong‐Kun Fun S. Kannan Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m368-m370
In the title compound, [UO2(C15H11O2)2(C14H14OS)], the UVI atom is coordinated by seven O atoms in a distorted pentagonal–bipyramidal geometry. Both diphenylpropane‐1,3‐dionate systems are nearly planar. The sulfoxide moiety is in a distorted tetrahedral geometry, while its two aromatic rings are nearly orthogonal to one another. The crystal packing is stabilized by two bifurcated hydrogen‐bonding interactions involving both uranyl O atoms. 相似文献
94.
J. X. Yang Z. Zhang Y. P. Tian J. Y. Wu Q. L. Liu A. Usman S. Chantrapromma H. K. Fun 《Russian Journal of Coordination Chemistry》2005,31(4):282-285
Copper(II) complex with piperidine-4-carboxylic acid (HPipe-4), Cu(HPipe-4)4(ClO4)2 (I) was prepared and characterized by IR, X-ray diffraction, and thermal analysis. The crystal is orthorhombic with space group Ccca, Z = 8, a =17.415(3) , b =17.399(2) , c = 21.426(3) . The copper atom has a square surrounding and is coordinated by four carboxylato oxygen atoms in monodentate coordination mode. Full-matrix least-squares refinements gave a final R value of 0.0723 for 22169 reflections. The complex consists of two perpendicularly arranged molecules differing slightly in conformations and shows a three-dimensional polymeric structure formed by hydrogen bonds.__________From Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 302–305.Original English Text Copyright © 2005 by Yang, Zhang, Tian, Wu, Liu, Usman, Chantrapromma, Fun.This article was submitted by the authors in English. 相似文献
95.
Anwar Usman Suchada Chantrapromma Hoong‐Kun Fun Bo‐Long Poh Chatchanok Karalai 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):o48-o50
In the title complex, C6H12N4·C8H8O3, the hexamethylenetetramine molecule accepts a single intermolecular O—H?N hydrogen bond from the hydroxy group of the 4‐hydroxy‐3‐methoxybenzaldehyde moiety. The non‐centrosymmetric crystal structure is built from alternating molecular sheets of 4‐hydroxy‐3‐methoxybenzaldehyde and hexamethylenetetramine molecules, and is stabilized by intermolecular O—H?N, C—H?O and C—H?π interactions. 相似文献
96.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Bao‐Guo Zhao Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):o24-o25
In the title compound, C20H16N2O5, both of the 1‐acetylisatin (1‐acetyl‐1H‐indole‐2,3‐dione) moieties are planar and form a dihedral angle of 74.1 (1)°. Weak intermolecular hydrogen bonds and C—H?π interactions stabilize the packing in the crystal. 相似文献
97.
Anwar Usman Suchada Chantrapromma Hoong‐Kun Fun Bo‐Long Poh Chatchanok Karalai 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o136-o138
In the title 1/2/2 adduct, C4H12N22+·2C6H3N2O5?·2H2O, the dication lies on a crystallographic inversion centre and the asymmetric unit also has one anion and one water molecule in general positions. The 2,4‐dinitrophenolate anions and the water molecules are linked by two O—H?O and two C—H?O hydrogen bonds to form molecular ribbons, which extend along the b direction. The piperazine dication acts as a donor for bifurcated N—H?O hydrogen bonds with the phenolate O atom and with the O atom of the o‐nitro group. Six symmetry‐related molecular ribbons are linked to a piperazine dication by N—H?O and C—H?O hydrogen bonds. 相似文献
98.
Fuad O. Usman Achyut R. Gogoi Dr. Jason C. Mixdorf Prof. Dr. Osvaldo Gutierrez Prof. Dr. Hien M. Nguyen 《Angewandte Chemie (International ed. in English)》2023,62(48):e202314843
Although there are many methods for the asymmetric synthesis of monosubstituted allylic fluorides, construction of enantioenriched 1,2-disubstituted allylic fluorides has not been reported. To address this gap, we report an enantioselective synthesis of 1,2-disubstituted allylic fluorides using chiral diene-ligated rhodium catalyst, Et3N ⋅ 3HF as a source of fluoride, and Morita Baylis Hillman (MBH) trichloroacetimidates. Kinetic studies show that one enantiomer of racemic MBH substrate reacts faster than the other. Computational studies reveal that both syn and anti π-allyl complexes are formed upon ionization of allylic substrate, and the syn complexes are slightly energetically favorable. This is in contrast to our previous observation for formation of monosubstituted π-allyl intermediates, in which the syn π-allyl conformation is strongly preferred. In addition, the presence of an electron-withdrawing group at C2 position of racemic MBH substrate renders 1,2-disubstituted π-allyl intermediate formation endergonic and reversible. To compare, formation of monosubstituted π-allyl intermediates was exergonic and irreversible. DFT calculations and kinetic studies support a dynamic kinetic asymmetric transformation process wherein the rate of isomerization of the 1,2-disubstituted π-allylrhodium complexes is faster than that of fluoride addition onto the more reactive intermediate. The 1,2-disubstituted allylic fluorides were obtained in good yields, enantioselectivity, and branched selectivity. 相似文献
99.
Potato peels as solid waste for the removal of heavy metal copper(II) from waste water/industrial effluent 总被引:1,自引:0,他引:1
A new sorbent potato peels, which are normally discarded as solid waste for removing toxic metal ion Cu(II) from water/industrial waste water have been studied. Potato peels charcoal (PPC) was investigated as an adsorbent of Cu(II) from aqueous solutions. Kinetic and isotherm studies were carried out by studying the effects of various parameters such as temperature, pH and solid liquid ratios. The optimum pH value for Cu(II) adsorption onto potato peels charcoal (PPC) was found to be 6.0. The thermodynamic parameters such as standard Gibb's free energy (Delta G degrees ), standard enthalpy (Delta H degrees ) and standard entropy (DeltaS degrees ) were evaluated by applying the Van't Hoff equation. The thermodynamics of Cu(II) adsorption onto PPC indicates its spontaneous and exothermic nature. The equilibrium data at different temperatures were analyzed by Langmuir and Freundlich isotherms. 相似文献
100.
Reconstruction of phylogenetic trees for very large datasets is a known example of a computationally hard problem. In this paper, we present a parallel computing model for the widely used Multiple Instruction Multiple Data (MIMD) architecture. Following the idea of divide-and-conquer, our model adapts the recursive-DCM3 decomposition method [Roshan, U., Moret, B.M.E., Williams, T.L., Warnow, T, 2004a. Performance of suptertree methods on various dataset decompositions. In: Binida-Emonds, O.R.P. (Eds.), Phylogenetic Supertrees: Combining Information to Reveal the Tree of Life, vol. 3 of Computational Biology, Kluwer Academics, pp. 301-328; Roshan, U., Moret, B.M.E., Williams, T.L., Warnow, T., 2004b. Rec-I-DCM3: A Fast Algorithmic Technique for reconstructing large phylogenetic trees, Proceedings of the IEEE Computational Systems Bioinformatics Conference (ICSB)] to divide datasets into smaller subproblems. It distributes computation load over multiple processors so that each processor constructs subtrees on each subproblem within a batch in parallel. It finally collects the resulting trees and merges them into a supertree. The proposed model is flexible as far as methods for dividing and merging datasets are concerned. We show that our method greatly reduces the computational time of the sequential version of the program. As a case study, our parallel approach only takes 22.1h on four processors to outperform the best score to date (Found at 123.7h by the Rec-I-DCM3 program [Roshan, U., Moret, B.M.E., Williams, T.L., Warnow, T, 2004a. Performance of suptertree methods on various dataset decompositions. In: Binida-Emonds, O.R.P. (Eds.), Phylogenetic Supertrees: Combining Information to Reveal the Tree of Life, vol. 3 of Computational Biology, Kluwer Academics, pp. 301-328; Roshan, U., Moret, B.M.E., Williams, T.L., Warnow, T., 2004b. Rec-I-DCM3: A Fast Algorithmic Technique for reconstructing large phylogenetic trees, Proceedings of the IEEE Computational Systems Bioinformatics Conference (ICSB)] on one dataset. Developed with the standard message-passing library, MPI, the program can be recompiled and run on any MIMD systems. 相似文献