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1.
New aromatic diamines substituted with a trifluoromethyl group in the side chain, 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, and 3,5‐diamino‐1‐[(4′‐trifluoromethyl phenoxy) phenyl] benzamide were synthesized and characterized and used to prepare polyimides by a one‐step high‐temperature polycondensation method. Experimental results indicated that the prepared polyimides possess good solubility in strong organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N′‐dimethylformamide, and N,N′‐dimethylacetamide. Homogeneous solutions with solid contents as high as 15–20% can be prepared, which are stable for storing longer than 2 weeks at room temperature. The polyimides exhibited glass‐transition temperatures of 249–292 °C and good thermal stability. The PI‐Ic and PI‐IIIc films prepared by casting the fully imidized polymer solutions showed good transparency with cutoff wavelengths at 320–330 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1572–1582, 2002  相似文献   

2.
The Staudinger reaction of organic azides tBuN3, 1‐Ad‐N3, and DippN3 (Dipp = 2,6‐diisopropylphenyl) with (R)‐N,N′‐bis(diphenylphosphanyl)‐2,2′‐diamino‐1,1′‐binaphthyl [(R)‐Binam‐P], obtained by an optimized procedure from (R)‐(+)‐Binam, Ph2PCl, and Et3N in DCM, leads to preparation of a series of new C2‐symmetric bis‐iminophosphonamide ligands [(R)‐Binam(Ph2PN(H)R)2] [R = tBu ( 1 ), Ad ( 2 ), and Dipp ( 3 )]. The molecular structure of 1· 2DMSO was confirmed by X‐ray structure analysis.  相似文献   

3.
The structures of cocrystals of 2,6‐dichlorophenol with 2,4‐diamino‐6‐methyl‐1,3,5‐triazine, C6H4Cl2O·C4H7N5, (III), and 2,6‐dichloroaniline with 2,6‐diaminopyrimidin‐4(3H)‐one and N,N‐dimethylacetamide, C6H5Cl2N·C4H6N4O·C4H9NO, (V), plus three new pseudopolymorphs of their coformers, namely 2,4‐diamino‐6‐methyl‐1,3,5‐triazine–N,N‐dimethylacetamide (1/1), C4H7N5·C4H9NO, (I), 2,4‐diamino‐6‐methyl‐1,3,5‐triazine–N‐methylpyrrolidin‐2‐one (1/1), C4H7N5·C5H9NO, (II), and 6‐aminoisocytosine–N‐methylpyrrolidin‐2‐one (1/1), C4H6N4O·C5H9NO, (IV), are reported. Both 2,6‐dichlorophenol and 2,6‐dichloroaniline are capable of forming definite synthon motifs, which usually lead to either two‐ or three‐dimensional crystal‐packing arrangements. Thus, the two isomorphous pseudopolymorphs of 2,4‐diamino‐6‐methyl‐1,3,5‐triazine, i.e. (I) and (II), form a three‐dimensional network, while the N‐methylpyrrolidin‐2‐one solvate of 6‐aminoisocytosine, i.e. (IV), displays two‐dimensional layers. On the basis of these results, attempts to cocrystallize 2,6‐dichlorophenol with 2,4‐diamino‐6‐methyl‐1,3,5‐triazine, (III), and 2,6‐dichloroaniline with 6‐aminoisocytosine, (V), yielded two‐dimensional networks, whereby in cocrystal (III) the overall structure is a consequence of the interaction between the two compounds. By comparison, cocrystal–solvate (V) is mainly built by 6‐aminoisocytosine forming layers, with 2,6‐dichloroaniline and the solvent molecules arranged between the layers.  相似文献   

4.
A straightforward and scalable eight‐step synthesis of new N‐heterocyclic carbenes (NHCs) has been developed from inexpensive and readily available 2‐nitro‐m‐xylene. This process allows for the preparation of a novel class of NHCs coined ITent (“Tent” for “tentacular”) of which the well‐known IMes (N,N′‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene), IPr (N,N′‐bis(2,6‐di(2‐propyl)phenyl)imidazol‐2‐ylidene) and IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene) NHCs are the simplest and already known congeners. The synthetic route was successfully used for the preparation of three members of the ITent family: IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene), IHept (N,N′‐bis(2,6‐di(4‐heptyl)phenyl)imidazol‐2‐ylidene) and INon (N,N′‐bis(2,6‐di(5‐nonyl)phenyl)imidazol‐2‐ylidene). The electronic and steric properties of each NHC were studied through the preparation of both nickel and palladium complexes. Finally the effect of these new ITent ligands in Pd‐catalyzed Suzuki–Miyaura and Buchwald–Hartwig cross‐couplings was investigated.  相似文献   

5.
Oxazolidin‐2‐ones are widely used as protective groups for 1,2‐amino alcohols and chiral derivatives are employed as chiral auxiliaries. The crystal structures of four differently substituted oxazolidinecarbohydrazides, namely N′‐[(E)‐benzylidene]‐N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C12H12N3O3, (I), N′‐[(E)‐2‐chlorobenzylidene]‐N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C12H12ClN3O3, (II), (4S)‐N′‐[(E)‐4‐chlorobenzylidene]‐N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C12H12ClN3O3, (III), and (4S)‐N′‐[(E)‐2,6‐dichlorobenzylidene]‐N,3‐dimethyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C13H13Cl2N3O3, (IV), show that an unexpected mild‐condition racemization from the chiral starting materials has occurred in (I) and (II). In the extended structures, the centrosymmetric phases, which each crystallize with two molecules (A and B) in the asymmetric unit, form A+B dimers linked by pairs of N—H...O hydrogen bonds, albeit with different O‐atom acceptors. One dimer is composed of one molecule with an S configuration for its stereogenic centre and the other with an R configuration, and possesses approximate local inversion symmetry. The other dimer consists of either R,R or S,S pairs and possesses approximate local twofold symmetry. In the chiral structure, N—H...O hydrogen bonds link the molecules into C(5) chains, with adjacent molecules related by a 21 screw axis. A wide variety of weak interactions, including C—H...O, C—H...Cl, C—H...π and π–π stacking interactions, occur in these structures, but there is little conformity between them.  相似文献   

6.
Two complexes of uranyl nitrate with N,N,N′,N′‐tetrabutyl‐2,6‐pyridinedicarboxamide (TBuDPA) and N,N′‐diethyl‐N,N′‐diphenyl‐2,6‐pyridinedicarboxamide (EtPhDPA) were synthesized and studied. The complex of tetraalkyl‐2,6‐pyridinedicarboxamide with metal nitrate was synthesized for the first time. XRD analysis revealed the different type of complexation: a 1:1 metal:ligand complex for EtPhDPA and complex with polymeric structure for TBuDPA. The quantum chemical calculations (DFT) confirm that both ligands form the most stable complexes that match the minimal values pre‐organization energy of the ligands.  相似文献   

7.
The compounds 5,6‐dihydro‐4H‐imidazo[4,5‐c][1,2,5]oxadiazole ( 3a , R?H), 4,6,10,12‐tetramethyl‐5,6,11,12‐tetrahydro‐4H,10H‐bis(1,2,5)oxadiazolo[3,4‐d:3′,4′‐I][1,3,6,8]tetraazecine ( 4b , R?CH3), N3,N3′‐methylenebis‐3,4‐diamino‐1,2,5‐oxadiazole ( 5a , R?H) and N3,N3′‐methylenebis(N,N′‐dimethyl‐3,4‐diamino‐1,2,5‐oxadiazolee) ( 5b , R?CH3) were synthesized from the reaction of formaldehyde with 3,4‐diamino‐1,2,5‐oxadiazole and N,N′‐3,4‐dimethylamino‐1,2,5‐oxadiazole in an acetonitrile.  相似文献   

8.
Two structures presenting an uncomplexed 2,6‐diaminopurine (dap) group are reported, namely 2,6‐diamino‐9H‐purine monohydrate, C5H6N6·H2O, (I), and bis(2,6‐diamino‐9H‐purin‐1‐ium) 2‐(2‐carboxylatophenyl)acetate heptahydrate, 2C5H7N6+·C9H6O42−·7H2O, (II). Both structures are rather featureless from a molecular point of view, but present instead an outstanding hydrogen‐bonding scheme. In compound (I), this is achieved through a rather simple independent unit content (one neutral dap and one water molecule) and takes the form of two‐dimensional layers tightly connected by strong hydrogen bonds, and interlinked by much weaker hydrogen bonds and π–π interactions. In compound (II), the fundamental building blocks are more complex, consisting of two independent 2,6‐diamino‐9H‐purin‐1‐ium (Hdap+) cations, one homophthalate [2‐(2‐carboxylatophenyl)acetate] dianion and seven solvent water molecules. The large number of hydrogen‐bond donors and acceptors produces 26 independent interactions, leading to an extended and complicated network of hydrogen bonds in a packing organization characterized by the stacking of interleaved anionic and cationic planar arrays. These structural characteristics are compared with those of similar compounds in the literature.  相似文献   

9.
Fluorinated copolyimides derived from 4,4′‐oxydiphthalic anhydride (ODPA) with 4,4′‐oxydianline (ODA) and trifluoromethyl‐containing aromatic diamines have been synthesized and characterized. The trifluoromethyl‐containing diamines include 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, 3,5‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] benzamide, 3,5‐diamino‐1‐[(3′‐trifluoromethyl) phenyl] benzamide, 1,4‐bis(4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl) benzene, 3,5‐diaminobenzenetrifluoride, 4,4′‐diamino‐4″‐(p‐trifluoromethyl phenoxy) triphenylamine, and 4‐[(4′‐trifluoromethylphenoxy) phenyl]‐2,6‐bis(4″‐aminophenyl)pyridine. Strong and flexible copolyimide films, produced by casting the polyamic acid solution followed by thermal imidization, exhibited great thermal stability and high mechanical properties. The polyimides had an ultraviolet–visible absorption cutoff at 330–340 nm and pretilt angles as high as 20° for nematic liquid crystals, making them great potential candidates for advanced liquid‐crystal display applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1583–1593, 2002  相似文献   

10.
The interaction of Cu^2+ complex of N,N'-bis(2-aminoethyl)-2,6-pyridinedicarboxamide (BAP) with DNA was studied by agarose gel electrophoresis analysis. The results indicate that the BAP-Cu^2+ complex can promote the cleavage of phosphodiester bond of supercoiled DNA at physiological condition, which is 3.2 × 10^6 times higher than DNA natural degradation. A hydrolytic cleaving mechanism through the cooperation of copper ions and functional amino groups was proposed.  相似文献   

11.
Investigation of DNA interactions with cationic lipids is of particular importance for the fabrication of biosensors and nanodevices. Furthermore, lipid/DNA complexes can be applied for direct delivery of DNA‐based biopharmaceuticals to damaged cells as non‐viral vectors. To obtain more effective and safer DNA vectors, the new cationic lipids 2‐tetradecylhexadecanoic acid‐{2‐[(2‐aminoethyl)amino]ethyl}amide (C I ) and 2‐tetradecylhexadecanoic acid‐2‐[bis(2‐aminoethyl)amino]ethylamide (C II ) were synthesized and characterized. The synthesis, physical–chemical properties and first transfection and toxicity experiments are reported. Special attention was focused on the capability of C I and C II to complex DNA at low and high subphase pH values. Langmuir monolayers at the air/water interface represent a well‐defined model system to study the lipid/DNA complexes. Interactions and ordering of DNA under Langmuir monolayers of the new cationic lipids were studied using film balance measurements, grazing incidence X‐ray diffraction (GIXD) and X‐ray reflectivity (XR). The results obtained demonstrate the ability of these cationic lipids to couple with DNA at low as well as at high pH value. Moreover, the observed DNA structuring seems not to depend on subphase pH conditions. An influence of the chemical structure of the lipid head group on the DNA binding ability was clearly observed. Both compounds show good transfection efficacy and low toxicity in the in vitro experiments indicating that lipids with such structures are promising candidates for successful gene delivery systems.  相似文献   

12.
The Schiff base compounds N,N′‐bis[(E)‐quinoxalin‐2‐ylmethylidene]propane‐1,3‐diamine, C21H18N6, (I), and N,N′‐bis[(E)‐quinoxalin‐2‐ylmethylidene]butane‐1,4‐diamine, C22H20N6, (II), crystallize in the monoclinic crystal system. These molecules have crystallographically imposed symmetry. Compound (I) is located on a crystallographic twofold axis and (II) is located on an inversion centre. The molecular conformations of these crystal structures are stabilized by aromatic π–π stacking interactions.  相似文献   

13.
4‐Aminoazobenzene‐derived silatranes bearing urea and aminosuccinimide as linker groups at the axial position are reported. The urea functionality is introduced in a silane ( 2 ) by the rearrangement reaction between 3‐isocyanatopropyltriethoxysilane and 4‐aminoazobenzene. N‐(3‐silatranylpropyl)‐N′‐[(p‐phenyldiazenyl)phenyl]urea and N‐[3‐(3,7,10‐trimethylsilatranyl)propyl]‐N′‐[(p‐phenyldiazene)phenyl]urea were prepared by transesterification reaction of 2 with triethanolamine and trisisopropanolamine, respectively. An efficient method for C? N bond formation is described for the synthesis of 3‐(silatranylpropyl)amino‐N‐[(p‐phenyldiazene)phenyl]pyrrolidine‐2,5‐dione and 3‐[(3,7,10‐trimethylsilatranyl)propyl]amino‐N‐[(p‐phenyldiazene)phenyl]pyrrolidine‐2,5‐dione via aza‐Michael addition reaction of aminopropylsilatranes with 4‐(N‐maleimido)azobenzene under mild conditions. All the compounds were well characterized using elemental analysis, spectroscopic techniques, thermogravimetric analysis and X‐ray diffraction. UV–visible spectroscopy indicates that the 4‐aminoazobenzene‐derived silatranes are capable acetate receptors. The synthesized compounds were screened for possible antimicrobial properties with the results showing a modest activity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

14.
A negative working and chemically amplified photosensitive polymer has been developed, which is based on poly(2,6‐dihydroxy‐1,5‐naphthalene) (PDHN), the crosslinker 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)]phenol, and the photoacid generator (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐(2‐methylphenyl)acetonitrile. PDHN, with a number‐average molecular weight of 25,000, was prepared by the oxidative coupling polymerization of 2,6‐dihydroxynaphthalene with di‐μ‐hydroxo‐bis[(N,N,N′,N′‐tetramethylethylenediamine)copper(II)] chloride in 2‐methoxyethanol at room temperature. The resulting PDHN showed a 5% weight loss temperature of 440 °C in nitrogen and a low dielectric constant of 2.82. The resist showed a sensitivity of 8.3 mJ cm?2 and a contrast of 11 when it was exposed to 436‐nm light, followed by postexposure baking at 100 °C for 5 min and development with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 °C. A fine negative image featuring 10‐μm line‐and‐space patterns was obtained on a film 3 μm thick exposed to 10 mJ cm?2 of ultraviolet light at 436 nm in the contact‐printed mode. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2235–2240, 2004  相似文献   

15.
In the present work, we study the reaction of singlet oxygen (1O2) with isolated DNA. Emphasis is placed on the identification and quantitative measurement of the DNA modifications that are produced by the reaction of 1O2 with DNA. For this purpose, calf‐thymus DNA was incubated with the endoperoxide of N,N′‐di(2,3‐dihydroxypropyl)‐1,4‐naphthalenedipropanamide, a chemical generator of 1O2. Thereafter, DNA was digested, and the resulting oxidized nucleosides were measured by means of a recently optimized high‐performance‐liquid‐chromatography tandem‐mass‐spectrometry assay. It was found that, among the different DNA lesions observed, 7,8‐dihydro‐8‐oxo‐2′‐deoxyguanosine is the major 1O2‐mediated DNA‐damage product. Interestingly, cyclobutane pyrimidine dimers, oxidized pyrimidine bases, 7,8‐dihydro‐8‐oxo‐2′‐deoxyadenosine, and 2,6‐diamino‐5‐formamido‐4‐hydroxypyrimidine are not formed, at least not in detectable amounts, following treatment of DNA with the 1O2 generator. The reported results strongly suggest that the decomposition of the endoperoxide provides a pure source of 1O2, and that reaction of 1O2 with isolated DNA induces the specific formation of 7,8‐dihydro‐8‐oxo‐2′‐deoxyguanosine.  相似文献   

16.
An α‐diimine Pd(II) complex containing chiral sec‐phenethyl groups, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dichloropalladium (rac‐ C1 ), was synthesized and characterized. rac‐ C1 was applied as an efficient catalyst for the Suzuki–Miyaura cross‐coupling reaction between various aniline halides and arylboronic acid in PEG‐400–H2O at room temperature. Among a series of aniline halides, rac‐ C1 did not catalyze the cross‐coupling of aniline chlorides and fluorides but efficiently catalyzed the cross‐coupling of aniline bromides and iodides with phenylboronic acid. The catalytic activity reduced slightly with increasing steric hindrance of the aniline bromides. The complexes {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]‐2,3‐butadiene}dichloropalladium and {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]acenaphthene}dichloropalladium were also found to be efficient catalysts for the reaction. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
Additions of beryllium–halide bonds in the simple beryllium dihalide adducts, [BeX2(tmeda)] (X=Br or I, tmeda=N,N,N′,N′‐tetramethylethylenediamine), across the metal center of a neutral aluminum(I) heterocycle, [:Al(DipNacnac)] (DipNacnac=[(DipNCMe)2CH]?, Dip=2,6‐diisopropylphenyl), have yielded the first examples of compounds with beryllium–aluminum bonds, [(DipNacnac)(X)Al‐Be(X)(tmeda)]. For sake of comparison, isostructural Mg–Al and Zn–Al analogues of these complexes, viz. [(DipNacnac)(X)Al‐M(X)(tmeda)] (M=Mg or Zn, X=I or Br) have been prepared and structurally characterized. DFT calculations reveal all compounds to have high s‐character metal–metal bonds, the polarity of which is consistent with the electronegativities of the metals involved. Preliminary reactivity studies of [(DipNacnac)(Br)Al‐Be(Br)(tmeda)] are reported.  相似文献   

18.
Reaction of CuI with 1 or 2 equivalent(s) N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine (BDDP) gives two different complexes, [Cu(I)μ‐(BDDP‐κP,Npy)]2 ( 1 ) and [Cu(BDDP‐κP,Npy)2]I ( 2 ), in high yields. The determination of the molecular structure show that both CuI atoms are tetrahedrally coordinated, rather than a square‐planar geometry reported for Cr0, NiII‐BDDP complexes before, which contains a planar tridentate chelate ring system. The introduction of AuCl(tht) (tht = tetrahydrothiophene) into [Cu(BDDP‐κP,Npy)2]I leads unexpectedly to the formation of a digold complex 2,6‐[(ClAuPh2P)HN]2C5H3N and dimeric [Cu(I)μ‐(BDDP‐κP,Npy)]2.  相似文献   

19.
The structures of N‐benzyl‐N′‐{6‐[(4‐carboxylatobenzyl)aminocarbonyl]‐2‐pyridylmethyl}guanidinium, C23H23N5O3, (I), and N‐[2‐(benzylaminocarbonyl)ethyl]‐N′‐{6‐[(4‐carboxylatobenzyl)aminocarbonyl]‐2‐pyridylmethyl}guanidinium monohydrate, C26H28N6O4·H2O, (II), both form three‐dimensional supramolecular hydrogen‐bonded networks based on a dimeric primary synthon involving carboxylate–guanidinium linkages. The differences in the geometries and hydrogen‐bonding connectivities are driven by the additional methylpropionamide group and water of crystallization of (II).  相似文献   

20.
Quantum mechanical exchange effects in purely organic N,N′‐dioxy‐2,6‐diazaadamantane biradical derivatives with promesogenic substituents have been studied. To determine intermolecular exchange energies, packing conditions of the radical core units in layered liquid crystalline phases are simulated using the Gaussian 09 program. The broken symmetry approach gives J ≈ 7 cm?1 for intramolecular ferromagnetic exchange interactions between nitroxyl radical centers in one molecule. Both ferromagnetic and antiferromagnetic intermolecular interactions are possible in this kind of systems according to the obtained calculation results. Depending on the mutual positioning and orientation of molecules, the intermolecular antiferromagnetic exchange constant can reach a value of ?50 cm?1, and the intermolecular ferromagnetic constant a value of 10 cm?1. The simultaneous presence of intramolecular and intermolecular exchange between spin‐carrying centers in this kind of supramolecularly ordered multispin systems is favorable for the formation of magnetically interacting chains and two‐dimensional networks. © 2016 Wiley Periodicals, Inc.  相似文献   

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