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1.
Superconducting Double Perovskite Bismuth Oxide Prepared by a Low‐Temperature Hydrothermal Reaction
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Mirza H. K. Rubel Prof. Akira Miura Prof. Takahiro Takei Prof. Nobuhiro Kumada M. Mozahar Ali Prof. Masanori Nagao Prof. Satoshi Watauchi Prof. Isao Tanaka Prof. Kengo Oka Prof. Masaki Azuma Prof. Eisuke Magome Prof. Chikako Moriyoshi Prof. Yoshihiro Kuroiwa Prof. A. K. M. Azharul Islam 《Angewandte Chemie (International ed. in English)》2014,53(14):3599-3603
Perovskite‐type structures (ABO3) have received significant attention because of their crystallographic aspects and physical properties, but there has been no clear evidence of a superconductor with a double‐perovskite‐type structure, whose different elements occupy A and/or B sites in ordered ways. In this report, hydrothermal synthesis at 220 °C produced a new superconductor with an A‐site‐ordered double perovskite structure, (Na0.25K0.45)(Ba1.00)3(Bi1.00)4O12, with a maximum Tc of about 27 K. 相似文献
2.
Cobalt‐Doped Perovskite‐Type Oxide LaMnO3 as Bifunctional Oxygen Catalysts for Hybrid Lithium–Oxygen Batteries
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Xiao Liu Dr. Hao Gong Dr. Tao Wang Dr. Hu Guo Dr. Li Song Dr. Wei Xia Dr. Bin Gao Zhongyi Jiang Linfei Feng Prof. Jianping He 《化学:亚洲杂志》2018,13(5):528-535
Perovskite‐type oxides based on rare‐earth metals containing lanthanum manganate are promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte. Perovskite‐type LaMnO3 shows excellent ORR performance, but poor OER activity. To improve the OER performance of LaMnO3, the element cobalt is doped into perovskite‐type LaMnO3 through a sol–gel method followed by a calcination process. To assess electrocatalytic activities for the ORR and OER, a series of LaMn1?xCoxO3 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) perovskite oxides were synthesized. The results indicate that the amount of doped cobalt has a significant effect on the catalytic performance of LaMn1?xCoxO3. If x=0.3, LaMn0.7Co0.3O3 not only shows a tolerable electrocatalytic activity for the ORR, but also exhibits a great improvement (>200 mV) on the catalytic activity for the OER; this indicates that the doping of cobalt is an effective approach to improve the OER performance of LaMnO3. Furthermore, the results demonstrate that LaMn0.7Co0.3O3 is a promising cost‐effective bifunctional catalyst with high performance in the ORR and OER for application in hybrid Li?O2 batteries. 相似文献
3.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(7):556-562
Unnatural cyclic α‐amino acids play an important role in the search for biologically active compounds and macromolecules. Enantiomers of natural amino acids with a d configuration are not naturally encoded, but can be chemically synthesized. The crystal structures of two enantiomers obtained by a method of stereoselective synthesis, namely (5R ,8S )‐8‐tert‐butyl‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]decane‐2,10‐dione, (1), and (5S ,8R )‐8‐tert‐butyl‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]decane‐2,10‐dione, (2), both C14H21NO4, were determined by X‐ray diffraction. Both enantiomers crystallize isostructurally in the space group P 21, with one molecule in the asymmetric unit and with the same packing motif. The crystal structures are stabilized by C—H…O hydrogen bonds, resulting in the formation of chains along the [100] and [010] directions. The conformation of the 3,6‐dihydro‐2H‐1,4‐oxazin‐2‐one fragment was compared with other crystal structures possessing this heterocyclic moiety. The comparison showed that the title compounds are not exceptional among structures containing the 3,6‐dihydro‐2H‐1,4‐oxazin‐2‐one fragment. The planar moiety was more frequently observed in derivatives in which this fragment was not condensed with other rings. 相似文献
4.
Masood Parvez Veejendra K. Yadav Rengarajan Balamurugan 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1084-1088
The crystal structures of the p‐bromobenzoates of cis‐4‐oxa‐1‐decalinyl (C16H19BrO3), trans‐4‐oxa‐1‐decalinyl (C16H19BrO3), N‐benzyl‐cis‐4‐aza‐1‐decalinyl (C23H26BrNO2), N‐benzyl‐trans‐4‐aza‐1‐decalinyl (C23H26BrNO2) and trans‐4‐thia‐1‐decalinyl (C16H19BrO2S) (decalin is perhydronaphthalene) have been determined as part of a study directed at predicting and interpreting the π‐facial selectivities of diastereotopic ketones in reactions with nucleophiles. All five structures are composed of molecules that are separated by normal van der Waals distances. In all five structures, the heterocyclic and cyclohexyl rings adopt chair conformations, and the p‐bromobenzoate groups are planar. 相似文献
5.
Jií Ludvík Jií Urban Jan Fbry Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):o259-o262
The title structures, both C10H10N4O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their molecular stacking and the hydrogen‐bonding patterns. 相似文献
6.
Bing Tang Yingjie Hu Hongxing Dong Liaoxin Sun Binbin Zhao Xiongwei Jiang Long Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16280-16286
Rubidium lead halides (RbPbX3), an important class of all‐inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t≈0.78, all‐inorganic RbPbBr3 has not been reported. Now, the crystal structure, X‐ray diffraction (XRD) pattern, and band structure of perovskite‐phase RbPbBr3 has now been investigated. Perovskite‐phase RbPbBr3 is unstable at room temperature and transforms to photoluminescence (PL)‐inactive non‐perovskite. The structural evolution and mechanism of the perovskite–non‐perovskite phase transition were clarified in RbPbBr3. Experimentally, perovskite‐phase RbPbBr3 was realized through a dual‐source chemical vapor deposition and annealing process. These perovskite‐phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475–540 nm) single‐mode lasing with a high Q of about 2100. 相似文献
7.
Hazel A. Sparkes Henry J. Sage Dmitry S. Yufit 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(9):872-875
The crystal structures of 1,2‐dimethyl‐3‐nitrobenzene, C8H9NO2, and 2,4‐dimethyl‐1‐nitrobenzene, C8H9NO2, which are liquids at room temperature, have been obtained through in‐situ cryocrystallization. Weak C—H...O and also π–π interactions are present in both crystal structures. 相似文献
8.
Gilles Gasser Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):o514-o516
The title compounds, C22H22N4 and C24H26N4O2 [alternative names: 2,6‐dibenzyl‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrrolo[3,4‐b; 3′,4′‐e]pyrazine and 2,6‐bis(4‐methoxybenzyl)‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrolo[3,4‐b;3′,4′‐e]pyrazine], two 1,2,3,5,6,7‐hexahydro‐2,4,6,8‐tetraaza‐s‐indacene derivatives, are both centrosymmetric and have similar S‐shaped structures. In the former, there are two independent molecules (A and B), both of which possess Ci symmetry. These two molecules are arranged such that the benzene ring substituent of molecule B is directed towards the plane of the benzene ring substituent of molecule A, with a dihedral angle of 55.4 (2)° between their planes. The shortest C—H⋯C distance is, however, only 3.21 (1) Å. In both compounds, the benzene ring substituents are almost perpendicular to the plane of the central pyrazine ring, and the pyrrolidine rings have perfect envelope conformations. In the crystal structures of both compounds, the molecules pack in a herring‐bone arrangement. 相似文献
9.
Ligia R. Gomes John Nicolson Low Ana S. M. C. Rodrigues James L. Wardell Camillo H. da Silva Lima Marcus V. N. de Souza 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(5):549-555
The compounds N′‐benzylidene‐N‐methylpyrazine‐2‐carbohydrazide, C13H12N4O, (IIa), N′‐(2‐methoxybenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide, C14H14N4O2, (IIb), N′‐(4‐cyanobenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc), N‐methyl‐N′‐(2‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C13H11N5O3, (IId), and N‐methyl‐N′‐(4‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C13H11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55–78°. These methylated pyrazine‐2‐carbohydrazides have supramolecular structures which are formed by weak C—H...O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π–π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0–6°. 相似文献
10.
Perovskite Oxide Nanosheets with Tunable Band‐Edge Potentials and High Photocatalytic Hydrogen‐Evolution Activity
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Prof. Dr. Kazuhiko Maeda Dr. Miharu Eguchi Takayoshi Oshima 《Angewandte Chemie (International ed. in English)》2014,53(48):13164-13168
Perovskite nanosheets of HCa2?xSrxNb3O10 and HCa2Nb3?yTayO10 with controlled band‐edge potentials were prepared. They worked as highly efficient heterogeneous photocatalysts for H2 evolution from a water/methanol mixture under band‐gap irradiation. The activity was found to depend on the composition. The highest activity was obtained with HCa2Nb2TaO10 nanosheets, recording an apparent quantum yield of approximately 80 % at 300 nm, which is the highest value for a nanosheet‐based photocatalyst reported to date. 相似文献
11.
Waseeq Ahmad Siddiqui Saeed Ahmad Muhammad Ilyas Tariq Hamid Latif Siddiqui Masood Parvez 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):o4-o6
The structures of N‐(2‐chlorophenyl)‐4‐hydroxy‐2‐methyl‐2H‐1,2‐benzothiazine‐3‐carboxamide 1,1‐dioxide and N‐(4‐chlorophenyl)‐4‐hydroxy‐2‐methyl‐2H‐1,2‐benzothiazine‐3‐carboxamide 1,1‐dioxide, both C16H13ClN2O4S, are stabilized by extensive intramolecular hydrogen bonds. The 4‐chloro derivative forms dimeric pairs of molecules lying about inversion centres as a result of intermolecular N—H...O hydrogen bonds, forming 14‐membered rings representing an R22(14) motif; the 2‐chloro derivative is devoid of any such intermolecular hydrogen bonds. The heterocyclic thiazine rings in both structures adopt half‐chair conformations. 相似文献
12.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(12):1151-1157
The 2‐amine derivatives of 5‐arylidene‐3H‐imidazol‐4(5H )‐one are a new class of bacterial efflux pump inhibitors, the chemical compounds that are able to restore antibiotic efficacy against multidrug resistant bacteria. 5‐Arylidene‐3H‐imidazol‐4(5H )‐ones with a piperazine ring at position 2 reverse the mechanisms of multidrug resistance (MDR) of the particularly dangerous Gram‐negative bacteria E. coli by inhibition of the efflux pump AcrA/AcrB/TolC (a main multidrug resistance mechanism in Gram‐negative bacteria, consisting of a membrane fusion protein, AcrA, a Resistant‐Nodulation‐Division protein, AcrB, and an outer membrane factor, TolC). In order to study the influence of the environment on the conformation of (Z )‐5‐(4‐chlorobenzylidene)‐2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]‐3H‐imidazol‐4(5H )‐one, ( 3 ), two different salts were prepared, namely with picolinic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium pyridine‐2‐carboxylate, C16H20ClN4O2+·C6H4NO2−, ( 3 a )} and 4‐nitrophenylacetic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium 2‐(4‐nitrophenyl)acetate, C16H20ClN4O2+·C8H6NO4−, ( 3 b )}. The crystal structures of the new salts were determined by X‐ray diffraction. In both crystal structures, the molecule of ( 3 ) is protonated at an N atom of the piperazine ring by proton transfer from the corresponding acid. The carboxylate group of picolinate engages in hydrogen bonds with three molecules of the cation of ( 3 ), whereas the carboxylate group of 4‐nitrophenylacetate engages in hydrogen bonds with only two molecules of ( 3 ). As a consequence of these interactions, different orientations of the hydroxyethyl group of ( 3 ) are observed. The crystal structures are additionally stabilized by both C—H…N [in ( 3 a )] and C—H…O [in ( 3 a ) and ( 3 b )] intermolecular interactions. The geometry of the imidazolone fragment was compared with other crystal structures possessing this moiety. The tautomer observed in the crystal structures presented here, namely 3H‐imidazol‐4(5H )‐one [systematic name: 1H‐imidazol‐5(4H )‐one], is also that most frequently observed in other structures containing this heterocycle. 相似文献
13.
Exploring a Lead‐free Semiconducting Hybrid Ferroelectric with a Zero‐Dimensional Perovskite‐like Structure
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Dr. Zhihua Sun Aurang Zeb Sijie Liu Chengmin Ji Tariq Khan Dr. Lina Li Prof. Maochun Hong Prof. Junhua Luo 《Angewandte Chemie (International ed. in English)》2016,55(39):11854-11858
Perovskite lead halides (CH3NH3PbI3) have recently taken a promising position in photovoltaics and optoelectronics because of remarkable semiconducting properties and possible ferroelectricity. However, the potential toxicity of lead arouses great environmental concern for widespread application. A new chemically tailored lead‐free semiconducting hybrid ferroelectric is reported, N‐methylpyrrolidinium)3Sb2Br9 ( 1 ), which consists of a zero‐dimensional (0‐D) perovskite‐like anionic framework connected by corner‐ sharing SbBr6 coordinated octahedra. It presents a large ferroelectric spontaneous polarization of approximately 7.6 μC cm?2, as well as notable semiconducting properties, including positive temperature‐dependent conductivity and ultraviolet‐sensitive photoconductivity. Theoretical analysis of electronic structure and energy gap discloses a dominant contribution of the 0‐D perovskite‐like structure to the semiconducting properties of the material. This finding throws light on the rational design of new perovskite‐like hybrids, especially lead‐free semiconducting ferroelectrics. 相似文献
14.
Jan Fbry Michal Duek Pemysl Vank Iegor Rafalovskyi Jií Hlinka Jií Urban 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1153-1160
The structures of 4‐chloro‐3‐nitroaniline, C6H5ClN2O2, (I), and 4‐iodo‐3‐nitroaniline, C6H5IN2O2, (II), are isomorphs and both undergo continuous (second order) phase transitions at 237 and 200 K, respectively. The structures, as well as their phase transitions, have been studied by single‐crystal X‐ray diffraction, Raman spectroscopy and difference scanning calorimetry experiments. Both high‐temperature phases (293 K) show disorder of the nitro substituents, which are inclined towards the benzene‐ring planes at two different orientations. In the low‐temperature phases (120 K), both inclination angles are well maintained, while the disorder is removed. Concomitantly, the b axis doubles with respect to the room‐temperature cell. Each of the low‐temperature phases of (I) and (II) contains two pairs of independent molecules, where the molecules in each pair are related by noncrystallographic inversion centres. The molecules within each pair have the same absolute value of the inclination angle. The Flack parameter of the low‐temperature phases is very close to 0.5, indicating inversion twinning. This can be envisaged as stacking faults in the low‐temperature phases. It seems that competition between the primary amine–nitro N—H...O hydrogen bonds which form three‐centred hydrogen bonds is the reason for the disorder of the nitro groups, as well as for the phase transition in both (I) and (II). The backbones of the structures are formed by N—H...N hydrogen bonding of moderate strength which results in the graph‐set motif C(3). This graph‐set motif forms a zigzag chain parallel to the monoclinic b axis and is maintained in both the high‐ and the low‐temperature structures. The primary amine groups are pyramidal, with similar geometric values in all four determinations. The high‐temperature phase of (II) has been described previously [Garden et al. (2004). Acta Cryst. C 60 , o328–o330]. 相似文献
15.
Akiko Hori Yasuhide Ishida Takahiro Kikuchi Kumiko Miyamoto Hiroshi Sakaguchi 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(12):o593-o597
In the crystal structure of 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one, C9H7N3OS, (I), the 1,2,4‐triazine moieties are connected by face‐to‐face contacts through two kinds of double hydrogen bonds (N—H...O and N—H...S), which form planar ribbons along the a axis. The ribbons are crosslinked through C—H...π interactions between the phenyl rings. The molecular structures of two regioisomeric compounds, namely 6‐phenyl‐2,3‐dihydro‐7H‐1,3‐thiazolo[3,2‐b][1,2,4]triazin‐7‐one, C11H9N3OS, (II), and 3‐phenyl‐6,7‐dihydro‐4H‐1,3‐thiazolo[2,3‐c][1,2,4]triazin‐4‐one, C11H9N3OS, (III), which were prepared by the condensation reaction of (I) with 1,2‐dibromoethane, have been characterized by X‐ray crystallography and spectroscopic studies. The crystal structures of (II) and (III) both show two crystallographically independent molecules. While the two compounds are isomers, the unit‐cell parameters and crystal packing are quite different and (II) has a chiral crystal structure. 相似文献
16.
Gary S. Nichol William Clegg 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(1):o13-o17
The three title compounds were obtained by reactions which mimic, with more extreme conditions, the in vivo metabolism of barbiturates. 1‐(2‐Cyclohex‐2‐enylpropionyl)‐3‐methylurea, C11H18N2O2, (I), and 2‐ethylpentanamide, C8H17NO, (III), both crystallize with two unique molecules in the asymmetric unit; in the case of (III), one unique molecule exhibits whole‐molecule disorder. 2‐Ethyl‐5‐methylhexanamide, C9H19NO, (II), crystallizes as a fully ordered molecule with Z′ = 1. In the crystal structures, three different hydrogen‐bonding motifs are observed: in (I) a combination of R22(4) and R22(8) motifs, and in (II) and (III) a combination of R42(8) and R22(8) motifs. In all three structures, one‐dimensional ribbons are formed by N—H...O hydrogen‐bonding interactions. 相似文献
17.
Svitlana V. Shishkina Irina S. Konovalova Pavlo V. Trostianko Anna O. Geleverya Sergiy M. Kovalenko Natalya D. Bunyatyan 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(11):1541-1553
This study of 3‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)‐2H‐chromen‐2‐one, C17H10N2O3, 1 , and 3‐[5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl]‐2H‐chromen‐2‐one, C16H9N3O3, 2 , was performed on the assumption of the potential anticancer activity of the compounds. Three polymorphic structures for 1 and two polymorphic structures for 2 have been studied thoroughly. The strongest intermolecular interaction is stacking of the `head‐to‐head' type in all the studied crystals. The polymorphic structures of 1 differ with respect to the intermolecular interactions between stacked columns. Two of the polymorphs have a columnar or double columnar type of crystal organization, while the third polymorphic structure can be classified as columnar‐layered. The difference between the two structures of 2 is less pronounced. Both crystals can be considered as having very similar arrangements of neighbouring columns. The formation of polymorphic modifications is caused by a subtle balance of very weak intermolecular interactions and packing differences can be identified only using an analysis based on a study of the pairwise interaction energies. 相似文献
18.
We employ dissipative particle dynamics (DPD) to examine the self‐assembly behavior of A2‐star‐(B‐alt‐C) molecules. We successfully observe various types of hierarchical structure‐within‐structures, such as A‐formed spheres in the matrix formed by B and C alternating layers, hexagonally packed A‐formed cylinders in the matrix with B and C segregated layers, B and C alternating layers‐within‐lamellae, coaxial B and C alternating domains within hexagonally packed BC‐formed cylinders in the A‐matrix, and co‐centric BC‐alternating domains within BC‐formed spheres in the A‐matrix, by increasing the A composition. Generally speaking, the small length‐scale B and C segregated domains are in parallel to the large length‐scale structures. This hierarchical periodicity along the same axis as well as the various characteristic structures, that the A2‐star‐(B‐alt‐C) copolymers display, are quite different from those in A‐block‐(B‐graft‐C) coil‐comb copolymers. Moreover, it is interesting to find that when the copolymer chain length increases, though the hierarchical structure type is maintained, the number of small length‐scale lamellae that can form within the large length‐scale structure increases. These hierarchical structures under various compositions are reported theoretically for the first time in the copolymer systems consisting of the alternating blocks, and are in good agreement with the most recent experimental work by Matsushita and co‐workers (Macromolecules 2007 , 40, 4023). 相似文献
19.
Krishnan Ravikumar Balasubramanian Sridhar Jagadeesh Babu Nanubolu Tamilselvan Rajasekaran Basi Venkata Subba Reddy 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(4):322-329
Four structures of oxoindolyl α‐hydroxy‐β‐amino acid derivatives, namely, methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐methoxy‐2‐phenylacetate, C24H28N2O6, (I), methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐ethoxy‐2‐phenylacetate, C25H30N2O6, (II), methyl 2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐[(4‐methoxybenzyl)oxy]‐2‐phenylacetate, C31H34N2O7, (III), and methyl 2‐[(anthracen‐9‐yl)methoxy]‐2‐{3‐[(tert‐butoxycarbonyl)amino]‐1‐methyl‐2‐oxoindolin‐3‐yl}‐2‐phenylacetate, C38H36N2O6, (IV), have been determined. The diastereoselectivity of the chemical reaction involving α‐diazoesters and isatin imines in the presence of benzyl alcohol is confirmed through the relative configuration of the two stereogenic centres. In esters (I) and (III), the amide group adopts an anti conformation, whereas the conformation is syn in esters (II) and (IV). Nevertheless, the amide group forms intramolecular N—H...O hydrogen bonds with the ester and ether O atoms in all four structures. The ether‐linked substituents are in the extended conformation in all four structures. Ester (II) is dominated by intermolecular N—H...O hydrogen‐bond interactions. In contrast, the remaining three structures are sustained by C—H...O hydrogen‐bond interactions. 相似文献
20.
N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide
Tei Tagg C. John McAdam Brian H. Robinson Jim Simpson 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(7):o388-o391
N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide, C19H19BrN2O2, (I), and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide, C20H21BrN2O2, (II), are an homologous pair of 1,8‐naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of π‐stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8‐naphthalimide derivatives. 相似文献