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1.
Linjun Qi Ming Dong Jinlong Qian Shuling Yu Prof. Xiaofeng Tong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202215397
Reductive elimination of alkyl−PdII−O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF4] and AgNO3 additive under toluene/H2O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd0-catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd0 catalyst to vinyl iodide, anion ligand exchange between I− and NO3−, alkene insertion and SN2-type alkyl−PdII−ONO2 reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO2 can facilitate dissociation of O2NO− ligand from the alkyl−PdII−ONO2 species, thus enabling the challenging alkyl−PdII−ONO2 reductive elimination to be feasible. 相似文献
2.
Payagala T Wanigasekara E Armstrong DW 《Analytical and bioanalytical chemistry》2011,399(7):2445-2461
Three new polymeric chiral stationary phases were synthesized based on (1S,2S)-1,2-bis(2,4,6-trimethylphenyl)ethylenediamine, (1S,2S)-1,2-bis(2-chlorophenyl)ethylenediamine, and (1S,2S)-1,2-di-1-naphthylethylenediamine via a simple free-radical-initiated polymerization in solution. These monomers are structurally
related to (1S,2S)-1,2-diphenylethylenediamine which is the chiral monomer used for the commercial P-CAP-DP polymeric chiral stationary phase
(CSP). The performance of these three new chiral stationary phases were evaluated in normal phase high-performance liquid
chromatography (HPLC) and supercritical fluid chromatography and the results were compared with those of the P-CAP-DP column.
All three new phases showed enantioselectivity for a large number of racemates with a variety of functional groups, including
amines, amides, alcohols, amino acids, esters, imines, thiols, and sulfoxides. In normal phase, 68 compounds were separated
with 28 baseline separations (Rs ≥ 1.5) and in SFC, 65 compounds were separated with 24 baseline separations. In total 72
out of 100 racemates were separated by these CSPs with 37 baseline separations. Complimentary separation capabilities were
observed for many analytes. The new polymeric CSPs showed similar or better enantioselectivities compared with the commercial
column in both HPLC and SFC. However, faster separations were achieved on the new stationary phases. Also, it was shown that
these polymeric stationary phases have good sample loading capacities while maintaining enantioselectivity. 相似文献
3.
Bruno Maurer Arnold Hauser Walter Thommen Karl H. Schulte-Elte Günther Ohloff 《Helvetica chimica acta》1980,63(1):293-314
The eight possible diastereoisomeric racemates of dactyloxene-B have been synthesized by a non-stereoselective route and their configurations and predominant conformations determined by 360-MHz-1H-NMR. and 90.5-MHz-13C-NMR. spectroscopy. Natural dactyloxene-B and -C are shown to have the relative configuration rel-(2R, 5R, 9S, 10R) and rel-(2R, 5S, 9S, 10R), respectively. 相似文献
4.
Coil-helix and sheet-helix block copolymers via macroinitiation from telechelic ROMP polymers
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Elizabeth Elacqua Anna Croom Diane S. Lye Marcus Weck 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):2991-2998
Coil-helix and sheet-helix block copolymers are synthesized by combining the ring-opening metathesis polymerization (ROMP) of norbornene or paracyclophanediene with the anionic polymerization of phenyl isocyanide. Key to the design is the use of an μ-ethynyl palladium (II) functionalized chain-transfer agent (CTA) that can be exploited in a stepwise manner for the termination of ROMP and the initiation of the anionic polymerization. Both the coil- and sheet-macroinitiators, and the ensuing covalent block copolymers, are analyzed using 1H NMR spectroscopy and gel-permeation chromatography. In all cases, the Pd-end group is maintained and all polymers demonstrate a monomodal distribution with dispersities (Đ) of 1.1–1.4. The resulting helix-coil and helix-sheet block copolymers formed by the macroinitiation route still demonstrate their intrinsic properties (fluorescence, preferential helix-sense). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2991–2998 相似文献
5.
Fanmengjing Wang David Pizzi Dr. Yizhihao Lu Kaiqiang He Prof. Kristofer J. Thurecht Prof. Matthew R. Hill Prof. Philip J. Marriott Prof. Mark M. Banaszak Holl Dr. Kristian Kempe Huanting Wang 《Angewandte Chemie (International ed. in English)》2023,62(8):e202212139
Chiral separation membranes have shown great potential for the efficient separation of racemic mixtures into enantiopure components for many applications, such as in the food and pharmaceutical industries; however, scalable fabrication of membranes with both high enantioselectivity and flux remains a challenge. Herein, enantiopure S-poly(2,4-dimethyl-2-oxazoline) (S-PdMeOx) macromonomers were synthesized and used to prepare a new type of enantioselective membrane consisting of a chiral S-PdMeOx network scaffolded by graphene oxide (GO) nanosheets. The S-PdMeOx-based membrane showed a near-quantitative enantiomeric excess (ee) (98.3±1.7 %) of S-(−)-limonene over R-(+)-limonene and a flux of 0.32 mmol m−2 h−1. This work demonstrates the potential of homochiral poly(2,4-disubstituted-2-oxazoline)s in chiral discrimination and provides a new route to the development of highly efficient enantioselective membranes using synthetic homochiral polymer networks. 相似文献
6.
Rong Fu Qing-Yu Zhao Dr. Han Han Wen-Li Li Fang-Yuan Chen Dr. Chun Tang Wei Zhang Si-Dan Guo Dai-Yuan Li Dr. Wen-Chao Geng Prof. Dr. Dong-Sheng Guo Prof. Dr. Kang Cai 《Angewandte Chemie (International ed. in English)》2023,62(51):e202315990
Accurately distinguishing between enantiomeric molecules is a fundamental challenge in the field of chemistry. However, there is still significant room for improvement in both the enantiomeric selectivity (KR(S)/KS(R)) and binding strength of most reported macrocyclic chiral receptors to meet the demands of practical application scenarios. Herein, we synthesized a water-soluble conjugated tubular host—namely, corral[4]BINOL—using a chiral 1,1′-bi-2-naphthol (BINOL) derivative as the repeating unit. The conjugated chiral backbone endows corral[4]BINOL with good fluorescent emission (QY=34 % ) and circularly polarized luminescence (|glum| up to 1.4×10−3) in water. Notably, corral[4]BINOL exhibits high recognition affinity up to 8.6×1010 M−1 towards achiral guests in water, and manifested excellent enantioselectivity up to 18.7 towards chiral substrates, both of which represent the highest values observed among chiral macrocycles in aqueous solution. The ultrastrong binding strength, outstanding enantioselectivity, and facile accessibility, together with the superior fluorescent and chiroptical properties, endow corral[4]BINOL with great potential for a wide range of applications. 相似文献
7.
Ben Chen Haibo You Liqun Fang Tingting Lin Ping Xu Chu Chu Shengqiang Tong 《Journal of separation science》2022,45(11):1847-1855
Analytical enantioseparations of five N-alkyl drugs, fluoxetine hydrochloride, labetalol, venlafaxine hydrochloride, trans-paroxol, and atropine sulfate, were investigated by reverse phase high-performance liquid chromatography with sulfobutylether-β-cyclodextrin as chiral mobile phase additive. Effects of various factors such as composition of mobile phase, concentration of cyclodextrins, and column temperature on retention and enantioselectivity were studied. Apparent formation constant between methanol, acetonitrile, and sulfobutylether-β-cyclodextrin were determined to be 2.90 × 10−3 and 1.00 × 10−4 L mmol−1 under 25°C using UV-spectrophotometry. Van't Hoff plots were used to investigate thermodynamic parameters for enantiomers–stationary phase interaction and formation of inclusion complex. Two retention models were employed individually for evaluation of inclusion complexation between five racemates and sulfobutylether-β-cyclodextrin. The second model with complex adsorption was more accord with the retention behavior of fluoxetine hydrochloride, labetalol, and venlafaxine hydrochloride enantiomers, while the first model was more consistent with the retention behaviors of trans-paroxol and atropine sulfate. In the selected mobile phase, stoichiometric ratio for both of inclusion complex was found to be 1:1. 相似文献
8.
Anna R. M. Hyyryläinen Jaana M. H. Pakarinen Enik Forró Ferenc Fülöp Pirjo Vainiotalo 《Journal of mass spectrometry : JMS》2010,45(2):198-204
Differentiation of β ‐amino acid enantiomers with two chiral centres was investigated by kinetic method with trimeric metal‐bound complexes. Four enantiomeric pairs of β ‐amino acids were studied: cis‐(1R,2S)‐, cis‐(1S,2R)‐, trans‐(1R,2R)‐ and trans‐(1S,2S)‐2‐aminocyclopentanecarboxylic acids (cyclopentane β ‐amino acids), and cis‐(1R,2S)‐, cis‐(1S,2R)‐, trans‐(1R,2R)‐, and trans‐(1S,2S)‐2‐aminocyclohexanecarboxylic acids (cyclohexane β ‐amino acids). The results showed that the choice of metal ion (Cu2+, Ni2+) and chiral reference compound (α‐ and β ‐amino acids) had an effect on the enantioselectivity. Especially, aromaticity of the reference compound was noted to enhance the enantioselectivity. The fixed‐ligand kinetic method, a modification of the kinetic method, was then applied to the same β ‐amino acids, with dipeptides used as fixed ligands. With this method, dipeptide containing an aromatic side chain enhanced the enantioselectivity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
Pei-Yun Jiang Zhi-Cheng Zhang Man-Wei Zhang 《Journal of polymer science. Part A, Polymer chemistry》1996,34(4):695-699
The kinetics of the K2S2O8-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier has been studied. The conversion-time curves are S-shaped. The following expressions have been obtained for the maximum rate of polymerization and the molecular weight of the polymers under the experimental conditions investigated: Rmax ∞ [K2S2O8]0.78[sodium acrylate]1.5[Span 80]0.1, (OVERLINE)M(/OVERLINE)u ∞ [K2S2O8]−0.37[sodium acrylate]2.9[Span 80]−0.2. The activation energy for the maximum rate of polymerization is 94.8 kJ mol−1. The results suggest a monomer–droplet–nucleation mechanism for the system studied. © 1996 John Wiley & Sons, Inc. 相似文献
10.
Wai-Kwok Wong Tat-Wai Chik Kin-Ning Hui Ian Williams Xue Feng Thomas C.W. Mak Chi-Ming Che 《Polyhedron》1996,15(24):4447-4460
The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)-tartrate and 1S,2S-diammoniumcyclohexane mono-(−)-tartrate with 2 equiv. of o-(diphenylphosphino)benzaldehyde in the presence of 2 equiv. of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diiminocyclohexane[1R,2R-cyclohexyl-P2N2, (R,R)-I] and N,N′-bis[o-(diphenylphosphino)benzylidene]-1S,2S-diiminocyclohexane [1S,2S-cyclohexyl-P2N2, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH4 in ethanol gave the optically pure reduced products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diaminocyclohexane[1R,2R-cyclohexyl-P2N2H4, (R,R)-II] and N,N′-bis[o-diphenylphosphine)benzylidene]-1S,2S-diaminocyclohexane[1S,2S-cyclohexyl-P2N2H4, (S,S)-II], respectively, in good yield. The coordination behaviour of I and II toward salts of CuI and AgI have been examined. The interaction of [Cu(C)3CN)4][X] (X = ClO4−, PF6−) with 1 equiv. of optically pure L4 [L4 = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL4][X] complexes, III–VI IIIa, L4 = (R,R)-I, X = PF6− IIIb, L4 = (R,R)-I, X = ClO4− IV, X = PF6−; Va, L4 = (R,R)-II, X = PF6−, Vb L4 = (R,R)-II, X= ClO4−, VI L4 = (S,S)-II, X = PF6−, in good yield. For the CuI complexes, the L4 ligand acted as a tetradentate ligand. However, a variable-temperature 31P[1H] NMR study of IIIb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction of AgBF4 with 1 equiv. of otpically pure L4 [L4 = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II gave the corresponding optically pure [AgL4][BF4] complexes, VII–X VII L4 = (R,R)-I; VIII, L4 = (S,S)-I; IX,L4 = (R,R)-II; X, L4 = (S,S)-II], in good yield. For the AgI complexes, the L4 ligand acted as a tetradentate ligand with the two amino groups coordinated unsymmetrically to the silver. A variable temperature 31P [1H] NMR study of VII suggests that at high temperature the complex exists as a tri-coordinated complex. The structurers of IV and IX were established by X-ray diffraction studies. 相似文献
11.
Anja Bhr AnneSophie Droz Martin Püntener Ulf Neidlein Sally Anderson Paul Seiler Franois Diederich 《Helvetica chimica acta》1998,81(11):1931-1963
The synthesis and carbohydrate-recognition properties of a new family of optically active cyclophane receptors, 1 – 3 , in which three 1,1′-binaphthalene-2,2′-diol spacers are interconnected by three buta-1,3-diynediyl linkers, are described. The macrocycles all contain highly preorganized cavities lined with six convergent OH groups for H-bonding and complementary in size and shape to monosaccharides. Compounds 1 – 3 differ by the functionality attached to the major groove of the 1,1′-binaphthalene-2,2′-diol spacers. The major grooves of the spacers in 2 are unsubstituted, whereas those in 1 bear benzyloxy (BnO) groups in the 7,7′-positions and those in 3 2-phenylethyl groups in the 6,6′-positions. The preparation of the more planar, D3-symmetrical receptors (R,R,R)- 1 (Schemes 1 and 2), (S,S,S)- 1 (Scheme 4), (S,S,S)- 2 (Scheme 5), and (S,S,S)- 3 (Scheme 8) involved as key step the Glaser-Hay cyclotrimerization of the corresponding OH-protected 3,3′-diethynyl-1,1′-binaphthalene-2,2′-diol precursors, which yielded tetrameric and pentameric macrocycles in addition to the desired trimeric compounds. The synthesis of the less planar, C2-symmetrical receptors (R,R,S)- 2 (Scheme 6) and (S,S,R)- 3 (Scheme 9) proceeded via two Glaser-Hay coupling steps. First, two monomeric precursors of identical configuration were oxidatively coupled to give a dimeric intermediate which was then subjected to macrocyclization with a third monomeric 1,1′-binaphthalene precursor of opposite configuration. The 3,3′-dialkynylation of the OH-protected 1,1′-binaphthalene-2,2′-diol precursors for the macrocyclizations was either performed by Stille (Scheme 1) or by Sonogashira (Schemes 4, 5, and 8) cross-coupling reactions. The flat D3-symmetrical receptors (R,R,R)- 1 and (S,S,S)- 1 formed 1 : 1 cavity inclusion complexes with octyl 1-O-pyranosides in CDCl3 (300 K) with moderate stability (ΔG0 ca. −3 kcal mol−1) as well as moderate diastereo- (Δ(ΔG0) up to 0.7 kcal mol−1) and enantioselectivity (Δ(ΔG0)=0.4 kcal mol−1) (Table 1). Stoichiometric 1 : 1 complexation by (S,S,S)- 2 and (S,S,S)- 3 could not be investigated by 1H-NMR binding titrations, due to very strong signal broadening. This broadening of the 1H-NMR resonances is presumably indicative of higher-order associations, in which the planar macrocycles sandwich the carbohydrate guests. The less planar C2-symmetrical receptor (S,S,R)- 3 formed stable 1 : 1 complexes with binding free enthalpies of up to ΔG0=−5.0 kcal mol−1 (Table 2). With diastereoselectivities up to Δ(ΔG0)=1.3 kcal mol−1 and enantioselectivities of Δ(ΔG0)=0.9 kcal mol−1, (S,S,R)- 3 is among the most selective artificial carbohydrate receptors known. 相似文献
12.
The epoxy-impregnated graphite tube electrode bulk modified with 2-mercaptobenzoxazole, employed in a wall-jet configuration, was found to be useful for the continuous flow and flow injection stripping voltammetric determinations of AgI, HgII and BiIII. For continuous flow, detection limits for AgI, HgII and BiIII were 1.8 × 10−10 M, 1.9 × 10−9 M and 9.5 × 10−9 M, respectively (10 min accumulation, S/N = 3). Precisions for 5.00 × 10−9 M AgI, 1.00 × 10−8 M HgII and 1.00 × 10−7 M BiIII were 10.5%, 5.77 % and 7.90% (relative standard deviations, n = 6), respectively. In the case of flow injection stripping, with a 500 μL injection loop, detection limits of 0.59 ng, 2.0 ng and 120 ng were obtained for AgI, HgII and BiIII, respectively (S/N = 3). Selected metal ions, inorganic and organic substances were investigated for interferences. The electrode was tested with a certified sample and then applied to the determinations of the metal ions in a urine and a sea-water sample. 相似文献
13.
Ketang Liu Ronghua Jin Tanyu Cheng Xiangming Xu Fei Gao Prof. Guohua Liu Prof. Hexing Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15546-15553
A functionalized periodic mesoporous organosilica with incorporated chiral bis(cyclohexyldiamine)‐based NiII complexes within the silica framework was developed by the co‐condensation of (1R,2R)‐cyclohexyldiamine‐derived silane and ethylene‐bridge silane, followed by the complexation of NiBr2 in the presence of (1R,2R)‐N,N′‐dibenzylcyclohexyldiamine. Structural characterization by XRD, nitrogen sorption, and TEM disclosed its orderly mesostructure, and FTIR and solid‐state NMR spectroscopy demonstrated the incorporation of well‐defined single‐site bis(cyclohexyldiamine)‐based NiII active centers within periodic mesoporous organosilica. As a chiral heterogeneous catalyst, this functionalized periodic mesoporous organosilica showed high catalytic activity and excellent enantioselectivity in the asymmetric Michael addition of 1,3‐dicarbonyl compounds to nitroalkenes, comparable to those with homogeneous catalysts. In particular, this heterogeneous catalyst could be recovered easily and reused repeatedly up to nine times without obviously affecting its enantioselectivity, thus showing good potential for industrial applications. 相似文献
14.
Esther Martinborough Tiziana Mordasini Denti Peter P. Castro Tara B. Wyman Carolyn B. Knobler Franois Diederich 《Helvetica chimica acta》1995,78(5):1037-1066
The complexation of N-benzyloxycarbonyl (Cbz) derivatives of the excitatory amino acids L -aspartic acid (Asp; 1 ), L -glutamic acid (Glu; 3 ), and, for the first time, L -kainic acid ((2S,3S,3S)-2-carboxy-4-(1-methylethenyl)pyrrolidine-3-acetic acid; Kai; 5 ) was studied in CDCl3 with a diversity of chiral receptors consisting of a 1,1′-binaphthyl spacer with (carboxamido)pyridine (CONH(py)) functionality attached to the 6,6′-positions in the major groove. Receptors of type A possess two N-(pyridin-2-yl)carboxamide H-bonding sites (e.g. 7 ), whereas type B-receptors have two N-(pyridine-6,2-diyl)acetamide residues attached (e.g. 8 and 9 ). Complexes of excitatory amino-acid derivatives and other, achiral α,β-dicarboxylic acids with these receptors are primarily stabilized by two sets of C?O···H? N and O? H ··· N H-bonds. Optically active type-A receptors such as (R)- and (S)- 7 showed a preference for the larger Glu derivative, whereas type- B receptors such as (R)- and (S)- 8 and (R)- and (S)- 9 formed more stable complexes with the smaller Cbz-Asp. To improve the poor enantioselectivity shown by 7–9 , additional functionality was introduced at the 7,7′-positions of the 1,1′-binaphthyl spacer, and the nature of the H-bonding sites in the 6,6′-positions was varied. Screening the diversity of new racemic receptors for binding affinity, which had been shown in many examples by Cram to correlate with enantioselectivity, demonstrated that (+)- 10 and (+)- 11 formed the most stable complexes with dicarboxylic acids, and these receptors were synthesized in enantiomerically pure form. Both are type- B binders and contain additional PhCH2O ( 10 ) and MeO ( 11 ) groups in the 7,7′-positions. By 1H-NMR binding titrations, the complexation of (R)- and (S)- 10 and (R)- and (S)- 11 with the excitatory amino-acid derivatives was studied in CDCl3, and association constants Ka between 103 and 2 · 105 l mol?1 were measured for the 1:1 host-guest complexes formed. Whereas both 10 and 11 formed stable complexes, enantioselective binding was limited to the PhCH2O-substituted receptor 10 , with the (R)-enantiomer complexing Cbz-Asp by 0.7 kcal mol?1 more tightly than the (S)-enantiomer. The structures of the diastereoisomeric complexes were analyzed in detail by experimental methods (complexation-induced changes in 1H-NMR chemical shifts, 1H{1H} nuclear Overhauser effect (NOE) difference spectroscopy) and computer modeling. These studies established that an unusual variety of interesting aromatic interactions and secondary electrostatic interactions are responsible for both the high binding affinity (? ΔG° up to 7.2 kcal mol?1) and the enantioselection observed with (R)- and (S)- 10 . In an approach to enhance the enantioselectivity by reducing the conformational flexibility of the 1,1′-binaphthyl spacer, an additional crown-ether binding site was attached to the 2,2′-positions in the minor groove of the type- B receptors (R)- and (S)- 48 . Both the binding affinity and the enantioselectivity (Δ(ΔG°) up to 0.7 kcal mol?1) in the complexation of the excitatory amino-acid derivatives by (R)- and (S)- 48 were not altered upon complexation of Hg(CN)2 at the crown-ether binding site, demonstrating lack of cooperativity between the minor- and major-groove recognition sites. 相似文献
15.
The Metal–Metal‐to‐Ligand Charge Transfer Excited State and Supramolecular Polymerization of Luminescent Pincer PdII–Isocyanide Complexes
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Qingyun Wan Dr. Wai‐Pong To Dr. Chen Yang Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2018,57(12):3089-3093
Pincer PdII–isocyanide complexes are described that display intermolecular interactions and emissive 3MMLCT excited states in aggregation state(s) at room temperature. The intermolecular PdII?PdII and ligand–ligand interactions drive these complexes to undergo supramolecular polymerization in a living manner. Comprehensive spectroscopic studies reveal a pathway with a kinetic trap that can be modulated by changing the counteranion and metal atom. The PdII supramolecular assemblies comprise two different aggregation forms with only one to be emissive. DFT/TDDFT calculations lend support to the MMLCT absorption and emission of these pincer PdII–isocyanide aggregates. 相似文献
16.
Anurag Mukherjee Prof. Dr. Suhrit Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(56):12874-12881
H-bonding driven J-type aggregation and cooperative supramolecular polymerization of a sulfur-substituted chiral naphthalene-diimide (NDI)-derivative (S,S)-NDI-2 in decane leads to remarkable enhancement of fluorescence quantum yield (43.3 % from 0.5 % in the monomeric state) and intense CPL signal in the aggregated state with a high luminescence dissymmetry factor (glum) of 4.6×10−2. A mixture of NDI-2 with a structurally similar NDI-derivative NDI-1 (mixture of racemic (S,S)- and (R,R)- isomers and the achiral derivative) in 1:9 (NDI-2/NDI-1) ratio, when heated and slowly cooled to room temperature, showed no enhanced CD band, indicating lack of any preferential helicity. However, when a monomeric solution of the NDI-1 in tetrahydrofuran (THF) was injected to preformed seed of NDI-2 in decane, a prominent CD signal appeared, indicating chiral amplification resulting in induced CPL with high glum value of 2.0×10−2 from mostly (>98.5 %) diastereomeric mixture. 相似文献
17.
Dmitri V. Konarev Alexey V. Kuzmin Salavat S. Khasanov Rimma N. Lyubovskaya 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(5):449-451
The title complex salt, (C16H36N)[MnBr(C32H16N8)] or (TBA)[MnIIBr(Pc)] (TBA is tetrabutylammonium and Pc is phthalocyaninate), has been obtained as single crystals by the diffusion technique and its crystal structure was determined using X‐ray diffraction. The high‐spin (S = ) [MnIIBr(Pc)]− macrocycle has a concave conformation, with an average equatorial Mn—N(Pc) bond length of 2.1187 (19) Å, an axial Mn—Br bond length of 2.5493 (7) Å and with the MnII cation displaced out of the 24‐atom Pc plane by 0.894 (2) Å. The geometry of the MnIIN4 fragment in [MnIIBr(Pc)]− is similar to that of the high‐spin (S = ) manganese(II) tetraphenylporphyrin (TPP) in [MnII(1‐MeIm)(TPP)] (1‐MeIm is 1‐methylimidazole). 相似文献
18.
C. Alvarez Ibarra M. L. Quiroga Feijoo M. S. Arias Perez J. de la Orden Parra 《Magnetic resonance in chemistry : MRC》1983,21(8):520-523
An assignment of relative configurations has been achieved for the diastereomeric racemates (1R2R,1S2S) and (1R2S,1S2R) of 3,3-dimethyl-1,2-diphenylbutan-1-ol through the comparative analysis of the respective chemical shifts induced by Eu(fod)3 in the 1H and 13C NMR spectra, and the corresponding conformational distribution. 相似文献
19.
Shigeo Tazuke Michihiko Asai Seizo Okamura 《Journal of polymer science. Part A, Polymer chemistry》1968,6(7):1809-1824
The polymerization of N-vinylcarbazole (VCZ) initiated by sodium chloroaurate (NaAuCl4·2H2O) in nitrobenzene was studied at 30°C. The rate of polymerization (Rp) is proportional to [AuIII] [VCZ] after a short induction period. When reducing agents (ascorbic acid, ferrocene, or mercury metal) are added to the system, the rate of polymerization in the dark increases. The Rp is relatively unaffected by addition of water and N-ethylcarbazole, but the polymerization is completely inhibited in the presence of ammonia. Oxygen and DPPH act as neither inhibitors nor retarders. Kinetic treatments based on the assumption that the active initiating species is AuII produced by reduction of AuIII by VCZ and other reducing agents explain the experimental results very well. 相似文献
20.
Dr. Céline Pichon Dr. Nicolas Suaud Valentin Jubault Dr. Carine Duhayon Prof. Nathalie Guihéry Dr. Jean-Pascal Sutter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(62):15484-15495
Trinuclear systems of formula [{Cr(LN3O2Ph)(CN)2}2M(H2LN3O2R)] (M=MnII and FeII, LN3O2R stands for pentadentate ligands) were prepared in order to assess the influence of the bending of the apical M−N≡C linkages on the magnetic anisotropy of the FeII derivatives and in turn on their Single-Molecule Magnet (SMM) behaviors. The cyanido-bridged [Cr2M] derivatives were obtained by assembling trans-dicyanido CrIII complex [Cr(LN3O2Ph)(CN)2]− and divalent pentagonal bipyramid complexes [MII(H2LN3O2R)]2+ with various R substituents (R=NH2, cyclohexyl, S,S-mandelic) imparting different steric demand to the central moiety of the complexes. A comparative examination of the structural and magnetic properties showed an obvious effect of the deviation from straightness of the M−N≡C alignment on the slow relaxation of the magnetization exhibited by the [Cr2Fe] complexes. Theoretical calculations have highlighted important effects of the bending of the apical C−N−Fe linkages on both the magnetic anisotropy of the FeII center and the exchange interactions with the CrIII units. 相似文献