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571.
572.
Keng Yoon Yeong Tze Shyang Chia Ching Kheng Quah Soo Choon Tan 《Journal of chemical crystallography》2018,48(4):170-176
The title compound, ethyl 2-(4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate dihydrate (5), was synthesized and its crystal structure was studied by single-crystal X-ray diffraction technique. Compound 5 is crystallized in the centrosymmetric triclinic space group \(P\bar {1}\) with Z?=?4 and Z′?=?2, and unit-cell parameters of a?=?8.9190 (3) Å, b?=?12.6888 (4) Å, c?=?14.7111 (5) Å, α?=?98.4855 (10)°, β?=?101.6379 (9)°, γ?=?95.4346 (10)° and V?=?1599.43 (9) Å3. Its starting material, 4-fluoro-3-nitrobenzoic acid (1), is crystallized in the non-centrosymmetric monoclinic space group P21 and Z?=?4 with unit-cell parameters of a?=?3.7170 (4) Å, b?=?12.6475 (13) Å, c?=?15.5237 (15) Å, α?=?90°, β?=?91.9786 (16)°, γ?=?90° and V?=?729.35 (13) Å3. It was noted that strong hydrogen bonds play important roles in the crystal packing of both compounds, especially in 5, in which the co-crystallized water molecules act as both strong hydrogen bond donor and strong hydrogen bond acceptor. 相似文献
Graphical Abstract
Two molecule of compound 5 crystallized in a non symmetrical manner with four co-crystallized water molecules which play an important role in the crystal packing as strong hydrogen-bond donors.573.
Yun Shan Peng Han Sheng Xu Pance Naumov S. Shanmuga Sundara Raj Hoong‐Kun Fun Ibrahim Abdul Razak Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1386-1388
The title compound, C10H9NO2Se, crystallizes as flat molecules linked by selenium–oxygen interactions [Se?O = 3.189 (4) Å] into a linear chain along the a axis of the triclinic cell. The bond dimensions that are derived from ab initio geometry optimization calculations are similar to those determined from the diffraction measurements. 相似文献
574.
Pan
e Naumov Gligor Jovanovski Sheng‐Zhi Hu Il‐Hwan Suh Ibrahim Abdul Razak Suchada Chantrapromma Hoong‐Kun Fun Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1016-1019
The short carbonyl bond in the title compound, [Cu2(C7H4NO3S)4(C3H4N2)4] [Liu, Huang, Li & Lin (1991). Acta Cryst. C 47 , 41–43], is an artifact of disorder in the isothiazol‐3(2H)‐one 1,1‐dioxide part of the 1,2‐benzisothiazol‐3(2H)‐one entity. In the present redetermination, all bond dimensions in the centrosymmetric dinuclear molecule are normal. The five‐coordinate Cu atom shows trigonal–bipyramidal coordination. Hydrogen bonds from the imidazole donor ligand link adjacent molecules into a two‐dimensional layer structure. 相似文献
575.
This report presents a continuing study of the morphological changes of polycaprolactone (PCL) with isothermal supercritical CO2 treatments at 304 atm and 35 °C in the presence of poly(vinyl chloride) (PVC). DSC and small‐angle X‐ray scattering (SAXS) data find that the CO2‐assisted melting of PCL at 304 atm and 35 °C recrystallized in the presence of PVC during depressurization of CO2 can result in a decreased thickness of crystal lamellar layers. Heterogeneity, with a size (21.7 nm for pure PCL) larger than the crystal layer thickness (8.2 nm for pure PCL) and the amorphous layer thickness (4.4 nm for pure PCL), is formed after the supercritical CO2 treatment. The size of this heterogeneity is found to enhance from 21.7 nm for pure PCL to 29.8 and 34.9 nm for the PCL samples containing 10 and 25 wt % PVC, respectively. These big heterogeneities in the PCL/PVC blends formed during CO2 depressurization might arise from the segregated PVC‐rich amorphous domains that are located between bundles of the lamellar stacks, possibly as a result of the molecular dragging on PCL during depressurization of the PCL‐interacted CO2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 85–93, 2006 相似文献
576.
577.
The chemist Harold Wiener found ??(G), the sum of distances between all pairs of vertices in a connected graph G, to be useful as a predictor of certain physical and chemical properties. The q‐analogue of ??, called the Wiener polynomial ??(G; q), is also useful, but it has few existing useful formulas. We will evaluate ??(G; q) for certain graphs G of chemical interest. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
578.
Xi‐Rui Zeng S. Shanmuga Sundara Raj Hoong‐Kun Fun Jing‐Lin Zuo Xiao‐Zeng You 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):941-942
In the title complex, [RuCl2(C16H36N4)]I3, the overall symmetry of the centrosymmetric cation is approximately C2h and the I anions are slightly asymmetric. The I?I distance is 4.313 (1) Å. The cations and the linear anions are arranged in alternate layers and thus form the intercalating structure. 相似文献
579.
[reaction: see text] Photoinduced reactions of 1-acetylisatin (IS) with diphenylacetylenes 1a-c, 1-(p-methoxyphenyl)propyne 2, and 1,4-diphenyl-1,3-butadiyne 3 gave beta,beta-disubstituted 3-alkylidene oxindoles 6-12 respectively via [2+2] cycloaddition of 3IS* with the alkyne and subsequent oxetene ring opening. Photoreactions of IS with phenylacetylenes 4a-d and cyclopropylacetylene 5 furnished the dispiroindole[3,2']furan[3',3' ']indoles 13 and 14. Compounds 13 and 14 are formed in tandem reactions initiated by [2+2] cycloaddition of 3IS* with the alkynes to give spirooxetenes Va and Vb, which upon spontaneous ring opening gave the alpha,beta-unsaturated aldehydes IVa and IVb. It is proposed that hydrogen abstraction of 3IS* from the C(O)-H functionality in IV followed by dissociation of the triplet isatin ketyl (A)-aldehyde acyl (B) radical pair and an oxygenphilic attack of the acyl radical B at the C3 carbonyl oxygen atom of a neutral IS gave the 2:1 (IS:4) radical C, which took part in an intramolecular radical cyclization to give the dispiroindole[3,2']furan[3',3' ']indoles 13 and 14. The regioselectivity in the [2+2] photocycloadditions of IS with 4 to afford the oxetene Va depends on the intervening of the more stable 1,4-diradical intermediates VI, which have a linear alpha-phenyl-substituted vinyl radical where the phenyl provides spin delocalization of the radical center at the sp carbon atom. 相似文献
580.