共查询到20条相似文献,搜索用时 15 毫秒
1.
Paul G. Jene James A. Ibers 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):705-707
The crystal structures of two elaborated‐porphyrin precursors have been determined. In the crystalline state, 2‐(1,3‐dithian‐2‐yl)benzaldehyde, C11H12OS2, has its dithiane ring in a slightly distorted chair conformation. The molecules pack in anti‐parallel chains. N‐{2‐[2‐(1,3‐Dioxan‐2‐yl)phenoxy]ethyl}phthalimide, C20H19NO5, is in a folded conformation. The dihedral angle between the phthalimide and phenyl planes is 80.07 (3)°. In the crystalline states, molecules stack on top of one another. 相似文献
2.
Graldine Calvet Nicolas Blanchard Cyrille Kouklovsky Rgis Guillot 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):o365-o368
The crystal structures of 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl benzoate, C13H15NO5, (I), 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C13H14ClNO5, (II), and 5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C11H11NO5, (III), have been determined in order to gain insight into the conformational preference of α‐benzoyloxynitroso. Unfavourable 1,3‐diaxial interactions force (I) and (II) to crystallize in the 2,5 twist‐boat conformation, whereas compound (III), lacking this destabilizing interaction, crystallizes in the chair conformation. 相似文献
3.
Xiu‐Li Wang Ke‐Ke Yang Yu‐Zhong Wang Zhi‐Xuan Zhou Yong‐Dong Jin 《Journal of polymer science. Part A, Polymer chemistry》2004,42(14):3417-3422
A new biodegradable starch graft copolymer, starch‐g‐poly(1,4‐dioxan‐2‐one), was synthesized through the ring‐opening graft polymerization of 1,4‐dioxan‐2‐one onto a starch backbone. The grafting reactions were conducted with various 1,4‐dioxan‐2‐one/starch feed ratios to obtain starch‐g‐poly(1,4‐dioxan‐2‐one) copolymers with various poly(1,4‐dioxan‐2‐one) graft structures. The microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was characterized in detail with one‐ and two‐dimensional NMR spectroscopy. The effect of the feed composition on the resulting microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3417–3422, 2004 相似文献
4.
Daniel E. Lynch Ian McClenaghan 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o704-o707
The structure of 2‐(pyrrolidin‐1‐yl)‐1,4‐naphthoquinone, C14H12.95Cl0.05NO2, (I), is actually a 0.95:0.05 mixture including 2‐chloro‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphthoquinone as a minor impurity, but (I) was resolved as a single molecule containing a Cl atom with 5% occupancy at the 3‐position. Compound (I) was prepared from the fully chloro‐substituted analogue in an attempt to produce the disubstituted pyrrolidinyl derivative. 2‐Phenylsulfanyl‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphthoquinone, C20H17NO2S, (II), was also prepared from 2‐chloro‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphthoquinone, using a strong exocyclic nucleophile. The structure of (II) differs from previous structures of 2,3‐dichloro‐1,4‐naphthoquinone and its derivatives in that the naphthoquinone ring is non‐planar. 相似文献
5.
Haruo Nishida Mitsuhiro Yamashita Masumi Nagashima Takeshi Endo Yutaka Tokiwa 《Journal of polymer science. Part A, Polymer chemistry》2000,38(9):1560-1567
To avoid the harmful effects of metallic residues in poly(1,4‐dioxan‐2‐one) (PPDO) for medical applications, the enzymatic polymerization of 1,4‐dioxan‐2‐one (PDO) was carried out at 60 °C for 15 h with 5 wt % immobilized lipase CA. The lipase CA, derived from Candida antarctica, exhibited especially high catalytic activity. The highest weight‐average molecular weight (Mw = 41,000) was obtained. The PDO polymerization by the lipase CA occurred because of effective enzyme catalysis. The water component appeared to act not only as a substrate of the initiation process but also as a chain cleavage agent. A slight amount of water enhanced the polymerization, but excess water depressed the polymerization. PPDO prepared by enzyme‐catalyzed polymerization is a metal‐free polyester useful for medical applications. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1560–1567, 2000 相似文献
6.
Jian‐Bing Zeng Madhusudhan Srinivansan Yi‐Dong Li Ramani Narayan Yu‐Zhong Wang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(24):5885-5890
Ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk was initiated by three titanium alkoxides, titanium dichlorodiisopropoxide (TiCl2(OiPr)2), titanium chlorotriisopropoxide (TiCl(OiPr)3), and titanium tetraisopropoxide (Ti(OiPr)4). The results indicate that the polymerization rate increased with number of OiPr groups in the initiator. High conversion of monomer (90%) and high molecular weight (11.9 × 104 g/mol) of resulting polymer can be achieved in only 5 min at 60 °C with Ti(OiPr)4 as an initiator. Analysis on nuclear magnetic resonance (NMR) spectra suggests the initiating sites for TiCl2(OiPr)2, TiCl(OiPr)3, and Ti(OiPr)4 to be 1.9, 2.6, and 3.8, respectively. Coordination‐insertion mechanism for the polymerization via cleavage of the acyl–oxygen bonds of the monomer was proved by NMR investigation. Kinetic studies indicate that polymerization initiated by Ti(OiPr)4 followed a first‐order kinetics, with an apparent activation energy of 33.7 kJ/mol. It is noteworthy that this value is significantly lower than earlier reported values with other catalysts, namely La(OiPr)3 (50.5 kJ/mol) and Sn(Oct)2 (71.8 kJ/mol), which makes it an attractive catalyst for reactive extrusion polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
7.
Christophe M. L. Vande Velde Jan K. Baeke Herman J. Geise Frank Blockhuys 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(5):o284-o287
The title compound, C30H34O8, crystallizes in the space group P with one‐half of a molecule in the asymmetric unit. A three‐dimensional network is generated by OCH3⋯π and CH⋯π interactions. The conformation of the C—C bond exocyclic to the central benzene ring is different from that of every other known derivative. A comparison of the geometry of the title molecule and of its solid‐state structure with other 2,4,6‐trimethoxy‐substituted PPV [i.e. poly(p‐phenylenevinylene)] oligomers, in particular the isopropoxy‐substituted compound, is provided. 相似文献
8.
Hamid Reza Nasiri M. Gregor Madej C. Roy D. Lancaster Harald Schwalbe Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o671-o673
The title compound, C14H12O4, forms crystals which appear monoclinic but are actually twinned triclinic. The asymmetric unit consists of two similar molecules, which differ only in the conformation of the 3‐oxobutyl side chain. The molecular conformation is characterized by an intramolecular O—H⋯O hydrogen bond between the hydroxy group and the adjacent carbonyl O atom. The crystal structure is stabilized by O—H⋯O hydrogen bonds connecting the molecules into zigzag chains running along the b axis. 相似文献
9.
Min‐Jung Lee Moon Seong Kang Min‐Ki Shin Jong‐Won Park Dae Sung Chung Chan Eun Park Soon‐Ki Kwon Yun‐Hi Kim 《Journal of polymer science. Part A, Polymer chemistry》2010,48(18):3942-3949
New amorphous semiconducting copolymers, poly(9,9‐dialkylfluorene)‐alt‐(3‐dodecylthienyl‐divinylbenzene‐3‐dodecylthienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized. The structure of copolymers was confirmed by H NMR, IR, and elemental analysis. The copolymers showed very good solubility in organic solvents and high thermal stability with high Tg of 178–185 °C. The weight average molecular weight was found to be 107,900 with polydispersity of 3.14 for PEFTVB and 76,700 with that of 3.31 for POFTVB. UV–vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB. Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB. The solution‐processed thin‐film transistors showed the carrier mobility of 2 × 10?4 cm2 V?1 s?1 for PEFTVB‐based devices and 2 × 10?5 cm2 V?1 s?1 for POFTVB‐based devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3942–3949, 2010 相似文献
10.
Daniel E. Lynch Ian McClenaghan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e588-e588
The structure of the title compound, C14H12ClNO2, (I), comprises essentially planar molecules which crystallize in a monoclinic lattice. C—H?O interactions exist to both naphthoquinone O atoms and the Cl atom. 相似文献
11.
Brian Ackers Alexander J. Blake Stuart J. Hill Peter Hubberstey 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):o640-o641
Molecules of the title compound, C12H8N2S2, which are effectively planar, have all four heteroatoms on the same side but do not have twofold symmetry. 相似文献
12.
Si‐Chong Chen Xiu‐Li Wang Ke‐Ke Yang Gang Wu Yu‐Zhong Wang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):3083-3091
Poly(vinyl alcohol)‐graft‐poly(1,4‐dioxan‐2‐one) (PVA‐g‐PPDO) with designed molecular structure was synthesized by a solid‐state polymerization. The solid‐state copolymerization was preceded by a graft copolymerization of PDO initiated with PVA as a multifunctional initiator, and Sn (Oct)2 as a coininitiator/catalyst in a homogeneous molten state. The polymerization temperature was then decreased and the copolymerization was carried out in a solid state. The products prepared by solid‐state polymerization were characterized by 1H NMR and DSC, and were compared with those synthesized in the homogeneous molten state. The degree of polymerization (Dp), degree of substitution (Ds), yield and the average molecular weight of the graft copolymer with different molecular structure were calculated from the 1H NMR spectra. The results show that the crystallization process during the solid‐state polymerization may suppress the undesirable inter‐ or intramolecular side reactions, then resulting in a controlled molecular structure of PVA‐g‐PPDO. The results of DSC measurement show that the molecular structures determine the thermal behavior of the PVA‐g‐PPDO. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3083–3091, 2006 相似文献
13.
Alexander S. Lyakhov Pavel N. Gaponik Yuri V. Grigoriev Ludmila S. Ivashkevich 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o381-o383
In the title compound, alternatively named 5,5′‐diphenyl‐2,2′‐methyleneditetrazole, C15H12N8, the dihedral angles between the tetrazole and benzene rings in the two 5‐phenyltetrazole fragments are 2.45 (6) and 10.01 (9)°. There is weak intermolecular C—H?N hydrogen bonding involving the H atoms of the methylene groups, which is responsible for the formation of two‐membered aggregates. C—H?π interactions in the crystal structure are discussed. 相似文献
14.
Guillaume Journot Reinhard Neier Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(3):o119-o122
In the title compounds, C11H18N2, (II), and C13H20N2O, (III), the pyrrolidine rings have twist conformations. Compound (II) crystallizes with two independent molecules (A and B) in the asymmetric unit. The mean planes of the pyrrole and pyrrolidine rings are inclined to one another by 89.99 (11) and 89.35 (10)° in molecules A and B, respectively. In (III), the amide derivative of (II), the same dihedral angle is much smaller, at only 13.42 (10)°. In the crystal structure of (II), the individual molecules are linked via N—H...N hydrogen bonds to form inversion dimers, each with an R22(12) graph‐set motif. In the crystal structure of (III), the molecules are linked via N—H...O hydrogen bonds to form inversion dimers with an R22(16) graph‐set motif. 相似文献
15.
Xiao‐Lan Zhu Gang Wu Zhi‐Cheng Qiu Yan Zhou Jie Gong Ke‐Ke Yang Yu‐Zhong Wang 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5214-5222
Lanthanum isopropoxide (La(OiPr)3) has been synthesized and employed for ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk as a single‐component initiator. The influences of reaction conditions such as initiator concentration, reaction time, and reaction temperature on the polymerization were investigated. The kinetics indicated that the polymerization is first‐order with respect to the monomer concentration. The Mechanistic investigations according to 1H NMR spectrum analysis demonstrated that the polymerization of PDO proceeded through a coordination‐insertion mechanism with a rupture of the acyl‐oxygen bond of the monomer rather than the alkyl‐oxygen bond cleavage. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5214–5222, 2008 相似文献
16.
Marciela Scarpellini Ademir Neves Adailton J. Bortoluzzi Antnio C. Joussef 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):356-358
In the title mononuclear complex, [Cu(C5H9N3)(C10H15N5)](ClO4)2, the CuII centre is surrounded by two N‐donor ligands, which impose a square‐pyramidal environment on the metal. The new tridentate ligand [2‐(imidazol‐4‐yl)ethyl][(1‐methylimidazol‐2‐yl)methyl]amine (HISMIMA) lies in the basal plane, while the histamine ligand occupies the apical and one of the basal positions around the CuII ion. 相似文献
17.
(5,6‐Dihydro‐1,4‐dithiin‐2‐yl)methanol as a Versatile Allyl‐Cation Equivalent in (3+2) Cycloaddition Reactions 下载免费PDF全文
Jan Hullaert Prof. Dr. Johan M. Winne 《Angewandte Chemie (International ed. in English)》2016,55(42):13254-13258
The title heterocyclic alcohol readily generates a sulfur‐substituted allylic cation upon simple treatment with a protic acid, thus facilitating a synthetically useful stepwise (3+2) cycloaddition reaction pathway with a range of conjugated‐olefin‐type substrates. The introduction of an allyl fragment in this way provided rapid access to a variety of cyclopentanoid scaffolds. The cyclic nature of the cation precursor alcohol was shown to be instrumental for efficient cycloaddition reactions to take place, thus indicating an attractive strategy for controlling the reactivity of heteroatom‐substituted allyl cations. The formal cycloaddition reaction is highly regio‐ and stereoselective and was also used for a short total synthesis of the natural product cuparene in racemic form through a cycloaddition–hydrodesulfurization sequence. 相似文献
18.
Narayan Bhattarai Wen Ying Jiang Hak Yong Kim Douck Rae Lee Soo Jin Park 《Journal of Polymer Science.Polymer Physics》2004,42(13):2558-2566
Novel biodegradable copolymers, poly(1,4‐dioxan‐2‐one‐co‐glycolide) [P(DON‐co‐GA)] containing a high proportion of 1,4‐dioxan‐2‐one (DON), were synthesized by copolymerizations of DON and glycolide (GA) at 120 °C for 16 h using stannous octoate as catalyst. Chemical composition and microstructural variation of the resulting copolymer were investigated by 1H‐ and 13C NMR and thermal properties by differential scanning calorimetry (DSC). From the 13C NMR spectra, it was observed that, apart from the expected preponderance of DON sequences, the minor component, GA, was indeed distributed at various points along the copolymer chain rather than incorporated as distinct blocks, which is consistent with a random sequence distribution. This view also was supported by the DSC results, which showed that most copolymers were amorphous except for one with a relatively high fraction of DON. The conclusion that it was a random structure rather than a statistical copolymer is discussed, using the theories about the mechanism of this type of polymerization in current as a reference. P(DON‐co‐GA) films were prepared by casting the copolymer solution in hexafluoroisopropanol (HFIP) with two concentrations of the polymeric solution (10 and 25 wt %). The in vitro hydrolytic degradation behaviors of these films were studied in phosphate buffer solution (pH = 7.4) at 37 °C and characterized by DSC, scanning electron microscopy, weight loss, and change in inherent viscosity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2558–2566, 2004 相似文献
19.
Edwin C. Constable Deborah Gusmeroli Catherine E. Housecroft Markus Neuburger Silvia Schaffner 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):o505-o509
We report the single crystal structures of 1,4‐bis(triisopropylsilyl)buta‐1,3‐diyne, C22H42Si2, and 1,4‐bis(biphenyl‐4‐yl)buta‐1,3‐diyne, C28H18, the packing in both of which illustrates the versatility of weak C—H⋯π supramolecular interactions in dictating the overall solid‐state structures. 相似文献
20.
Peiwen Zhou James D. Fisher Richard J. Staples Ashwani Vij Nicholas R. Natale 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1146-1147
The title compound, C14H21NO5, possesses an isoxazolyl group in the axial position of the 1,3‐dioxanyl ring. The two rings are rotated about the bond joining them such that the two C(methyl)—C(dioxanyl)—C—C torsion angles are 92.1 (2) and ?84.1 (2)°. In this conformation, neither the methyl nor ethoxycarbonyl substituents on the isoxazole are presented towards the dioxanyl chair. 相似文献