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1.
The complexation‐induced critical aggregation concentrations of 1‐pyrenemethylaminium by mono‐p‐sulfonatocalix[n]arenes and bis‐p‐sulfonatocalix[n]arenes (n=4, 5) were systemically measured by fluorescence spectroscopy. In all cases, the complexation‐induced critical aggregation concentration decreases by about 3 times upon addition of p‐sulfonatocalix[n]arenes. However, the optimal molar ratios for the aggregation of 1‐pyrenemethylaminium by mono‐p‐sulfonatocalix[n]arenes and bis‐p‐sulfonatocalix[n]arenes are distinctly different: For mono‐p‐sulfonatocalix[n]arenes, the optimum mixing ratio for the aggregation of 1‐pyrenemethylaminium is 1:4 mono‐p‐sulfonatocalix[n]arenes/1‐pyrenemethylaminium, whereas only 2.5 molecules of 1‐pyrenemethylaminium can be bound by one cavity of bis‐p‐sulfonatocalix[n]arenes. The intermolecular complexation of mono‐p‐sulfonatocalix[n]arenes and bis‐p‐sulfonatocalix[n]arenes with 1‐pyrenemethylaminium led to the formation of two distinctly different nanoarchitectures, which were shown to be nanoscale vesicle and rod aggregates, respectively, by using dynamic laser scattering, TEM, and SEM. This behavior is also different from the fiber‐like aggregates with lengths of several micrometers that were formed by 1‐pyrenemethylaminium itself above its critical aggregation concentration. Furthermore, the obtained nanoaggregates exhibit benign water solubility, self‐labeled fluorescence, and, more importantly, temperature responsiveness.  相似文献   

2.
Bishomochinon     
Two isomeric 2,4,6,8-tetrabromo-cyclooctane-1,5-diones ( 8a and 8b ) are formed in the tetrabromination of cyclooctane-1,5-dione ( 7 ). Treatment of a mixture of 8a and 8b with triethylamine gives rise to anti- 1,3-dibromo-bishomoquinone ( 9 ), which is reduced with zinc to anti-bishomoquinone ( 4 ) in a 65% overall yield. Either 8a or 8b , when heated with copper powder in a high vacuum, affords 1-bromo( 11 ) and 1,3-dibromo-anti-bishomoquinone ( 9 ), anti-bishomoquinone ( 4 ) itself as well as its sys-isomer ( 5 ). The anti-configuration was assigned to 4 on the basis of its reduction to two diols, one of which showed NMR. coupling of its two isochronic carbinol protons with one cis-vicinal proton and one trans-vicinal proton. Spectral data of the compounds are discussed. Of particular interest is the inversion of the chemical shifts of exo- and endo-methylene protons when comparing the NMR.-spectra of anti- and syn-bishomoquinone.  相似文献   

3.
The treatment of di‐o‐quinone 4,4′‐(ethane‐1,2‐diyl)‐bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH2–CH2–Q, 1 ) leads to its rearrangement to form di‐p‐quinomethide 4,4′‐(ethane‐1,2‐diylidene)bis(2‐hydroxy‐3,6‐di‐tert‐butyl‐cyclohexa‐2,5‐dienone) ( 2 ). The subsequent oxidation of 2 by an alkaline solution of K3[Fe(CN)6] yielded the new di‐o‐quinone 4,4′‐(ethene‐1,2‐diyl)bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH=CH–Q, 3 ), which contains an ethylene bridge. The formation of mono‐ and poly‐reduced derivatives of 2 and 3 with potassium, thallium was studied by EPR technique. The dinuclear thallium derivative of 3 , Tl(SQ–CH=CH–SQ)Tl, was found to exist in the diamagnetic quinomethide form. The most stable derivatives of 2 and 3 are triphenyltin(IV) bis‐p‐quinomethide‐phenolate ( 4 ) and triphenylantimony(V) bis‐catecholate ( 5 ), which have been synthesized and isolated. The molecular structures of 2 , 3 , and 5 were characterized by single‐crystal X‐ray diffraction.  相似文献   

4.
At a pressure of 10?6 Torr the ion cyclotron resonance spectra of p-benzoquinone, methyl-p-benzoquinone, tetramethyl-p-benzoquinone and tetrafluoro-p-benzoquinone are identical to the normal mass spectra. Above 10?5 Torr the spectra show a variety of signals for product ions. From double resonance measurements it was shown that all the product ions are formed by addition of the molecular ion or of a fragment ion to a neutral quinone molecule. In most cases the addition is accompanied by the elimination of carbon monoxide.  相似文献   

5.
(E) and (Z)‐1,2‐bis(trifluoromethyl)ethene‐1,2‐dicarbonitrile (BTE; (=E) and (Z)‐1,2‐bis(trifluoromethyl)but‐2‐enedinitrile) were reacted with an excess of methyl vinyl ether, used as solvent, and furnished 1 : 2 adducts 6 (54%) and cyclobutanes 3 as 1 : 1 adducts (41%). The four diastereoisomeric bis‐adducts 6 (different ratios from (E) and (Z)‐BTE) are derivatives of 1‐azabicyclo[4.2.0]oct‐5‐ene; X‐ray analyses and 19F‐NMR spectra revealed their structures. Since the cyclobutanes 3 are resistant to vinyl ether, the pathways leading to mono‐ and bis‐adducts must compete on the level of the intermediate l,4‐zwitterions 1 and 2 . The latter either cyclize to the cyclobutanes 3 or to six‐membered cyclic ketene imines 8 which accept a second molecule of vinyl ether to yield the bis‐adducts 6 . The occurrence of the highly strained ketene imines 8 gains credibility by comparison to stable seven‐membered cyclic ketene imines recently reported.  相似文献   

6.
In the present work, a series of eight new imidazole, 4,5–dichloroimidazole, 4,5–diphenylimidazole and benzimidazole based nitro–functionalized mono–N –heterocyclic carbene (NHC)–silver(I) acetate ( 7a–d ) and bis–NHC–silver(I) hexafluorophosphate complexes ( 8a–d ) were synthesised by the reaction of the corresponding azolium hexafluorophosphate salts ( 6a–d ) with silver(I) acetate and silver(I) oxide in methanol and acetonitrile, respectively. All the synthesised compounds were fully characterized by various spectroscopic techniques and elemental analyses. Additionally, the structure of bis–(1–benzyl–3–(p –nitrobenzyl)–4,5–dichloroimidazole–2–ylidene)silver(I) hexafluorophosphate complex ( 8b ) was confirmed by single crystal X–ray diffraction analysis. Preliminary in vitro antibacterial evaluation was conducted for all the compounds ( 6a–d) , ( 7a–d) , and ( 8a–d) by Kirby–Bauer's disc diffusion method followed by the determination of Minimum Inhibitory Concentration (MIC) from broth macrodilution method against five standard bacteria; two Gram–positive bacterial strains (Staphylococcus aureus and Bacillus subtilis) and three Gram–negative bacterial strains ( Escherichia coli , Shigella sonnei, and Salmonella typhi). All the hexafluorophosphate salts ( 6a – d) were found inactive against the tested bacterial strains and their corresponding mono– and bis–NHC–silver(I) complexes ( 7a–d and 8a–d ) exhibited moderate to high antibacterial activity with MIC value in the range 8–128 μg/mL. In addition, preliminary in vitro anticancer potential of all the silver(I) complexes ( 7a–d and 8a–d ) was determined against the human derived breast adenocarcinoma cells (MCF 7) by MTT assay. All the mono– and bis–NHC–silver(I) complexes ( 7a–d and 8a–d ) orchestrated high anticancer potential with IC50 values ranging from 10.39 to 59.56 nM. In comparison, mono– NHC–silver(I) complexes performed better than the bis–NHC–silver(I) complexes.  相似文献   

7.
A strong acceptor substituent at the nitrogen atom of the N-substituted p-quinone monoimine decreases the stability of the halogen-containing cyclohexene structures formed at the addition of a halogen molecule to the C=C bond of the quinoid ring. As a result of the bromination of N-benzoyl-2-methyl-1,4-benzoquinone monoimine alongside the usual products of addition and substitution the 5-benzoyloxy-2,3,6-tribromo-6-methylcyclohex-2-ene-1,4-dione was isolated.  相似文献   

8.
Three novel bis(β‐cyclodextrin (CD))s with flexible glycol linkers, i.e., ethylene glycol‐bridged bis(6‐hydroxy‐6‐deoxy‐β‐CD) ( 2 ), diethylene glycol‐bridged bis(6‐hydroxy‐6‐deoxy‐β‐CD) ( 3 ), and triethylene glycol‐bridged bis(6‐hydroxy‐6‐deoxy‐β‐CD) ( 4 ) have been synthesized by the reaction of mono[6‐O‐(p‐toluenesulfonyl)]‐β‐CD with corresponding materials. The inclusion complexation behaviors of these compounds 2 – 4 with organic dyes; that is, acridine red (=N‐[(3Z)‐6‐(methylamino)‐3H‐xanthen‐3‐ylidene]methanaminium chloride; AR), neutral red (=N8,N8,3‐trimethylphenazine‐2,8‐diamine hydrochloride; NR), ammonium 8‐anilinonaphthalene‐1‐sulfonate (ANS), sodium 6‐(p‐toluidinyl)‐naphthalene‐2‐sulfonate (TNS), rhodamine B (RhB) and brilliant green (=N‐(4‐{[4‐(diethylamino)cyclohexa‐2,5‐dien‐1‐yl](phenyl)methyl}cyclohex‐2‐en‐1‐ylidene)‐N‐ethyl‐ethanaminium hydrogen sulfate; BG), have been investigated at 25° in phosphate buffer (pH 7.20) by ultraviolet, fluorescence, and 2D‐NMR spectroscopy. The results indicate that the two linked CD units may cooperatively bind a guest, and the molecular binding ability toward dye guests, especially bent ANS, T‐shaped RhB, and triangular BG, can be extended. This cooperative binding mode is confirmed by Job's experiments and 2D‐NMR investigations. Furthermore, the complex stability depends greatly on the linker length of these glycol‐bridged bis(β‐CD)s and the size and shape of guest. The higher binding ability and selectivity of dye molecules by bis(β‐CD)s 2 – 4 are discussed from the viewpoint of size/shape‐fit concept and multiple recognition mechanism.  相似文献   

9.
1,3-Dipolar cycloaddition reactions of anhydro-5-hydroxyoxazolium hydroxide 3 generated from 2-piperidinecarboxylic acid and acetic anhydride, with dimethyl and diethyl acetylene-dicarboxylates, dibenzoylacetylene, p-benzoquinone, and 1,4-naphthoquinone gave the corresponding tetrahydroindolizines. In the case of the reaction with p-benzoquinone, the dihydroindolizine 12 was also formed. The primary N-bridged lactone intermediate 4 was isolated from the reaction of 2 with dibenzoylacetylene. Several attempted conversions of these tetrahydroindolizines into the corresponding aromatic indolizines were fruitless.  相似文献   

10.
Herein we report on the synthesis, structure, and optical properties of the fluorescent blue phosphazene dye 1,6‐bis(dimethylamino)‐2,5,7,10‐tetraazo‐1,6λ5‐diphosphapyrene, which was isolated as the unexpected product of the reaction between 1,4,5,8‐(tetraamino)naphthalene and [P(NMe2)3Br]Br. This dye, which turned out to be soluble in water and a range of organic solvents (including hexane, tetrahydrofuran / petroleum ether, acetonitrile, and ethanol), was structurally characterized by XRD. Its absorption as well as emission spectra and their sensitivity to pH variations were analyzed. The experimental work is complemented by quantum chemical calculations on the possible intermediate on the way to the isolated product and on its pKa value.  相似文献   

11.
Due to using (R)‐ or (S)‐α‐methylbenzylamine as a chiral auxiliary, and low‐temperature regime for reduction of the intermediate ferrocenyl‐mono‐ or 1,1′‐bis‐ketimines, the corresponding secondary mono‐ or 1,1′‐bis‐amines were prepared with high diastereoselectivity. Removal of the α‐methylbenzyl group afforded the optically active primary mono‐ and bis‐ferrocenylethylamines in high yields. The absolute configuration of (R,R)‐ 3a and (S,S)‐ 3b was determined by X‐ray single crystal diffraction.  相似文献   

12.
A series of bis(pyreneamide) macrocycles, synthesized in two steps from THF, THP, oxepane and 1,4‐dioxane, are tested as chemosensors for a large range of mono‐, di‐ and trivalent cations. In their native states, these macrocycles exhibit a strong excimer fluorescence that is quenched upon the addition of the metal ions (alkaline, alkaline earth, p‐, d‐, and f‐block metals). UV‐Vis spectrophotometric titrations, cyclic voltammetry, excimer fluorescence quenching, and transient absorption spectroscopy experiments helped characterize the On‐Off changes occurring upon binding and demonstrate that the highest stability constants are obtained with divalent cations Ca2+ and Ba2+ specifically.  相似文献   

13.
At the halogenation of N-aroyl-2,6(3,5)-dimethyl-1,4-benzoquinone imines we found the halogenation of methyl groups to occur. The bromination of N-aroyl-2,6-dimethyl-1,4-benzoquinone imines yielded 3,6-dibromo-2,6-dimethyl-5-aroyloxycyclohex-2-ene-1,4-diones due to the strong acceptor property of the ArCO group and high redox potentials of N-aroyl derivatives. In the chlorination of N-aroyl-3,5-dimethyl-1,4-benzoquinone imines the chlorine addition to the C=C bond of the quinoid ring proceeded both by the trans- and syn-scheme.  相似文献   

14.
Reactions of o-Quinones with Amines and Proteins. 7a-Methyl-5,6,7,7a-tetrahysroindole Derivatives from 4-Methylcatechol and Enamines Methyl l-[2′-(methoxycarbonyl)ethyl]-7a-methyl-5,6-dioxo-5.6.7,7a-tetrahydro-indole-3-carboxylate ( 1 ) was isolated after the oxidation of 4-methylcatechol with silver ( 1 ) oxide in the presence of b?-alanine methyl ester in glacial acetic acid. The formation of 1 requires in situ dehydrogenation of the b?-aminocarboxylate and addition of the resulting enamine to 4-methyl-1,2-benzoquinone. Reaction of ethyl 3-(phenylamino)crotonate with 4-methyl-1,2-benzoquinone afforded ethyl 2,7a-dimethyl-5,6-dioxo-1-phenyl-5,6,7,7a-tetrahydroindole-3-carboxylate ( 6 ). Despite the fact that the yields are low, the addition of enamines to o-quinones represents an interesting novel extension of the Nenitzescu-reaction which is well known in the p-quinone series. Compound 1 may be considered as a novel model for the crosslinking of proteins by o-quinones. Formation of 1 was, however, not observed under physiological conditions.  相似文献   

15.
The covalently templated bis‐functionalization of C70, employing bis‐malonate 5 tethered by an anti‐disubstituted dibenzo[18]crown‐6 (DB18C6) ether, proceeds with complete regiospecificity and provides two diastereoisomeric pairs of enantiomeric C70 crown ether conjugates, (±)‐ 7a and (±)‐ 7b , featuring a five o'clock bis‐addition pattern that is disfavored in sequential transformations (Scheme 1). The identity of (±)‐ 7a was revealed by X‐ray crystal‐structure analysis (Fig. 6). With bis‐malonate 6 containing a syn‐disubstituted DB18C6 tether, the regioselectivity of the macrocylization via double Bingel cyclopropanation changed completely, affording two constitutionally isomeric C70 crown ether conjugates in a ca. 1 : 1 ratio featuring the twelve ( 16 ) and two o'clock ((±)‐ 15 ) addition patterns, respectively (Scheme 3). The X‐ray crystal‐structure analysis of the twelve o'clock bis‐adduct 16 revealed that a H2O molecule was included in the crown ether cavity (Figs. 7 and 8). Two sequential Bingel macrocyclizations, first with anti‐DB18C6‐tethered ( 5 ) and subsequently with syn‐DB18C6‐tethered ( 6 ) bis‐malonates, provided access to the first fullerene bis‐crown ether conjugates. The two diastereoisomeric pairs of enantiomers (±)‐ 28a and (±)‐ 28b were formed in high yield and with complete regioselectivity (Scheme 9). The cation‐binding properties of all C70 crown‐ether conjugates were determined with the help of ion‐selective electrodes (ISEs). Mono‐crown ether conjugates form stable 1 : 1 complexes with alkali‐metal ions, whereas the tetrakis‐adducts of C70, featuring two covalently attached crown ethers, form stable 1 : 1 and 1 : 2 host‐guest complexes (Table 2). Comparative studies showed that the conformation of the DB18C6 ionophore imposed by the macrocyclic bridging to the fullerene is not particularly favorable for strong association. Reference compound (±)‐ 22 (Scheme 4), in which the DB18C6 moiety is attached to the C70 sphere by a single bridge only and, therefore, possesses higher conformational flexibility, binds K+ and Na+ ions better by factors of 2 and 20, respectively. Electrochemical studies demonstrate that cation complexation at the crown ether site causes significant anodic shifts of the first reduction potential of the appended fullerene (Table 3). In case of the C70 mono‐crown ether conjugates featuring a five o'clock functionalization pattern, addition of 1 equiv. of KPF6 caused an anodic shift of the first reduction wave in the cyclic voltammogram (CV) by 70 to 80 mV, which is the result of the electrostatic effect of the K+ ion bound closely to the fullerene core (Fig. 14). Addition of 2 equiv. of K+ ions to C70 bis‐crown ether conjugates resulted in the observation of only one redox couple, whose potential is anodically shifted by 170 mV with respect to the corresponding wave in the absence of the salt (Fig. 16). The synthesis and characterization of novel tris‐ and tetrakis‐adducts of C70 are reported (Schemes 5 and 6). Attempts to prepare even more highly functionalized derivatives resulted in the formation of novel pentakis‐ and hexakis‐adducts and a single heptakis‐adduct (Scheme 7), which were characterized by 1H‐ and 13C‐NMR spectroscopy (Fig. 10), as well as matrix‐assisted laser‐desorption‐ionization mass spectrometry (MALDI‐TOF‐MS). Based on predictions from density‐functional‐theory (DFT) calculations (Figs. 12 and 13), structures are proposed for the tris‐, tetrakis‐, and pentakis‐adducts.  相似文献   

16.
New N-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines were synthesized, and their thiocyanation gave 5-alkyl(trifluoromethyl)sulfonylamino-1,3-benzoxathiol-2-ones. An intermediate thiocyanation product, 5-trifluoromethylsulfonylamino-1,3-benzoxathiol-2-imine, was isolated for the first time.  相似文献   

17.
In order to elucidate the mechanism of radiation-induced polymerization of methyl methacrylate adsorbed on silica gel, the effects of p-benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited by p-benzoquinone at levels above 10-2 mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease as p-benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected by p-benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose-rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in formation mechanism.  相似文献   

18.
Styrene is oxidized by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), affording hydroquinone mono(2-phenylethyl) ether. Kinetic studies (50°C in CHCl3) show that the reaction is faster under N2 than under air and takes placevia intramolecular H-atom transfer within the 1:1 and 1:2 DDQ-styrene charge-transfer complexes. The semiquinone radical intermediate is reoxidized to DDQ by O2 when the latter is present, therefore, the apparent rate of DDQ reduction is lower. Stability constants of the CT-complexes and kinetic parameters for the oxidation are reported.  相似文献   

19.
Antipodal (`trans‐1') Diels‐Alder bis‐adducts 3 and 7 – 9 of [5,6]fullerene‐C60Ih ( 1 ) with some anthracenes were prepared highly regioselectively by heating mixtures of the solid 1 and anthracene or of (one of) three alkyl‐substituted anthracenes in the absence of solvents (Scheme 2). Other bis‐cycloadducts were not detected, but lesser amounts of mono‐cycloadducts 2 and 4 – 6 , respectively, were also formed. Heating of solvent‐free mixtures of 1 and three other alkyl‐substituted anthracenes did not result in a detectable amount of (antipodal) bis‐cycloadducts. The antipodal bis‐adduct 7 of 1 and of 1‐methylanthracene was analyzed by X‐ray crystallography. The preparative outcome of heating of anthracenes and solid 1 parallels the result of the heating of the corresponding crystalline mono‐adducts of anthracenes and 1 . Both approaches reveal a remarkably consistent dependence of the reaction upon the presence and position of alkyl substituents at the anthracene unit. The regioselective assembly of antipodal bis‐adducts from anthracene(s) and 1 cannot be rationalized by their (inherent molecular) stability, but it indicates the crucial control of the lattice.  相似文献   

20.
Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10?6 S cm?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (Tg) of the ion conductive phase by ~5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10?6 S cm?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the Tg of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007  相似文献   

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