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04/2011;
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ABSTRACT: The reaction of 4′-hydroxy-4-methyl azobenzene (1) and 1,6-dibromohexane afforded 6-bromo-1-((4-((4-met hylphenyl)azo)phenyl)oxy)hexane (2), which further reacted with p-tert-butylcalix[4]arene to give the calix[4]arene derivative (3) whose lower rim had been modified by the azobenzene photochromic group. The structure of 3 was characterized by 1H-nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS). The fluorescence intensity of compound
3 was two to four times higher than that of compounds 1 and 2 as the azobenzene group concentration in the range of 1.6 × 10−5 to 8.0 × 10−4 mol/L, indicating that the fluorescence quantum yield of the azobenzene group had been improved through being attached to
the calix[4]arene skeleton. The liquid crystalline behavior of compound 3 was studied by polarized microscopy (POM) and differential scan calorimeter (DSC). Compound 3 exhibited the enchased texture of a smectic liquid crystal from 209.4°C to 219.5°C on heating, while 2 exhibited a liquid crystalline phase from 87.4 to 83.2°C on cooling. It was found that the calix[4]arene skeleton was a good
platform for conformation immobilization of azobenzene photochromic group and the formation of liquid crystalline.
Frontiers of Chemistry in China 06/2007; 2(3):292-295.
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Synthetic Communications 01/2007; 37(15):2601-2608. · 1.06 Impact Factor
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ABSTRACT: First published as an Advance Article on the web 22nd September 2005 1,2-alt p-tert-Butylcalix[4]arene tetraacid can self-assemble via hydrogen-bonds into a one dimensional network with channel of diameter ca. 0.5 nm, and ethanol molecules were incorpo-rated into the network playing roles of hydrogen bond donors and acceptors simultaneously. One-dimensional nano structures have become the focus of intensive research owing to their unique applications in meso-scopic physics and for the fabrication of nanoscale devices. 1 Bottom-up chemical construction was used to generate nano-structures. 2 Nano tubes have been made from cyclic peptides, 3 hydrogen-bonded rosettes 4 and coordination complexes. 5 Thus supramolecular tubes, organized by suitable building blocks via reversible bonds, have been paid much attention on. 6,7 Calixarenes have attracted consideration as molecular plat-forms to construct supramolecular synthons. 8 Rebek and co-workers have shown some self-complementary cone conforma-tion calixarenes. 9 Davis also reported a 1,3-alternate calix[4]-arene self-assembled into nanotubes in the presence of Na 1 . 10 Reinhoudt's calixarene rosette architecture formed the tem-plate-assisted assembly of a hydrogen-bonded trimer. 4 By observation with Atom Force Microscopy (AFM), we found that a fibriform assembly was formed by a one dimen-sional network composed of 1,2-alternate p-tert-butylcalix[4]-arene tetraacetic acid. X-Ray diffraction analysis indicated that the assembly contained channels of ca. 0.5 nm diameter assisted by solvent ethanol molecules. No similar assembling phenomena could be observed with the 1,3-alternate conformer with an analogous structure under similar conditions. Here we present the results. 1,2-alt-Tetrakis((ethoxycarbonyl)methoxy)-p-tert-butylcalix [4]arene 1 and 1,3-alt-tetrakis((ethoxycarbonyl)methoxy)-p-tert-butylcalix[4]arene 2 were synthesized as reported in the literature. 11 These two calixarene conformers were derived with difficulty from p-tert-butylcalix[4]arene directly and were seldom studied. The 1,2-alt p-tert-butylcalix[4]arene tetraacid 3 or 1,3-alt p-tert-butylcalix[4]arene tetraacid 4 (Fig. 1) could be obtained in quantitative yields by reacting corresponding p-tert-butylcalix[4]arene tetraethyl acetate with NaOH in a solu-tion of ethanol and water. The solubility of compounds 3 and 4 was quite different. Compound 3 was sparingly soluble in CHCl 3 . When 3 was added to pure CDCl 3 only the signals of ethanol were observed in the 1 H NMR spectrum. 12 After a little CF 3 COOH was added, the obvious signals of 3 appeared (Fig. 2) besides the signals of ethanol. The singlet at 1.29 ppm is due to all the tert-butyl groups. A pair of doublets at 3.30 ppm and 4.60 ppm, and a singlet at 4.01 ppm could be assigned as four methylene protons of ArCH 2 Ar each. These signals of ArCH 2 Ar proved 3 to exist as the 1,2-alternate structure. The doublets at 4.19 ppm and 4.40 ppm are the OCH 2 CO protons in different chemical environments. Two doublets at 7.08 ppm and 7.34 ppm showed two different ArH groups in the mole-cule of 3. The 1,3-alt p-tert-butylcalix[4]arene tetraacid 4 is very soluble in CHCl 3 : all proton resonance signals of 4 were clear and sharp peaks in the 1 H NMR spectrum in pure CDCl 3 . 12 The 10 À6 mol L À1 ethanol solutions of compound 3 and 4 were deposited on a mica substrate, and observed by AFM. 13 Fig. 3 showed that ordered fibres appeared on the mica substrate for compound 3. The width of the nano fibres was about 50–100 nm, while the length of the fibres was above 1000 nm or more. The width and height confirmed that the nano
New Journal of Chemistry 11/2005; 29(11):1390. · 2.61 Impact Factor
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ABSTRACT: 5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene (diglycidyloxy-C[4]) has been synthesized and
used for preparation of a sol-gel solid-phase microextraction fiber with enhanced extraction efficiency. The sol-gel procedure
was developed using a sol solution containing diglycidyloxy-C[4] as organic component and both tetraethoxysilane and 3-aminopropyltriethoxysilane
(KH-550) as precursors. No additional catalysts were used and no centrifugation was performed. Diglycidyloxy-C[4] was highly
chemically reactive toward KH-550 even at room temperature, which increased the calixarene content of the coating, simplified
the sol-gel procedure, reduced the sol-gel reaction time, enhanced the polarity of the coating, and improved extraction performance.
The sol-gel mixture also had very good coating properties and was highly uniformly distributed on the surface of the fiber;
because of these characteristics several fibers could be prepared from one sol-gel solution. Efficient extraction of trace
analytes (µg L−1 levels) from aqueous samples was accomplished using this kind of new fiber. Very low detection limits (ng L−1 level) were achieved for most polar (aromatic amines and phenols) and nonpolar (polycyclic aromatic hydrocarbons) aromatic
compounds by SPME followed by gas chromatography with flame ionization detection. The new coating had excellent solvent and
thermal (350 °C) stability. Lifespan was also good—a fiber could be used more than 300 times in headspace SPME without substantial
changes in the properties of the coating.
Chromatographia 10/2005; 62(9):519-525. · 1.20 Impact Factor
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ABSTRACT: Under selected conditions, 1,2:3,4-doubly crowned p-tert-butyl-thiacalix[4]arene in cone conformation and 1,3:2,4-doubly crowned p-tert-butyl-thiacalix[4]arene in 1,3-alternate conformation were obtained through aminolysis in high to good yield, respectively.
Journal of Chemical Research 03/2005; 2005(4):240-241. · 0.04 Impact Factor
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Synthetic Communications 01/2005; 35(24):3179-3186. · 1.06 Impact Factor
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ABSTRACT: Detection of aromatic amines without derivatization was carried out using a new solid-phase microextraction fiber coated with 25,27-dihydroxy-26,28-(1,10-dioxo-4,7-diaza-3,8-dioxooctamethylene)-p-tert-butylcalix[4]arene (amide bridged-C[4]). The new fiber shows excellent selectivity and sensitivity for the tested amines (aniline, o-toluidine, 2,4-dimethylaniline, 3,4-dimethylaniline, N-ethyl-m-toluidine, and N,N-diethylaniline). The coating has high thermal stability (up to 380 C) and solvent stability. Experimental conditions, such as extraction temperature and time, pH and ionic strength were optimized. The method proposed here shows good linearity and low detection limits ranged from 1.2 to 40 ng.L–1. Application of this method was demonstrated through the determination of aromatic amines in wastewater from a pharmaceutical plant.
Chromatographia 12/2004; 61(1):75-80. · 1.20 Impact Factor
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ABSTRACT: A novel solid-phase microextraction (SPME) fiber coated with 25,27-dihydroxy-26, 28-(1', 10'-dioxa-4', 7'-diaza-3', 8'-dioxooctylene ) -p-tert-butylcalix [ 4 ] arene/hydroxy-terminated silicone oil (amide bridged -C[4]/OH-TSO) was prepared with sol-gel technology and applied to the analysis of aliphatic amines and aromatic amines without derivatization. It demonstrated high thermal stability of up to 380 degrees C and stability in organic and inorganic solvents, a prolonged lifetime of over 200 times for headspace SPME, great fiber-to-fiber reproducibility with a relative standard deviation (RSD) of no more than 6.3% for aromatic amines, etc. Due to the introduction of polar amide bridge in calixarene molecules, polarity of the coating increases and thus the fiber shows better extraction efficiency in most of the investigated aliphatic amines and aromatic amines compared to the extraction efficiency of commercial fibers, indicating specific selectivity and sensitivity to amines. The detection limits (LODs) were determined to be 0.19 - 39.51 microg/L, the linear ranges were 3 orders of magnitude with a precision better than 5.1% for aliphatic amines, and they were 1.21 - 40.73 ng/L, 4 - 6 orders of magnitude with a precision better than 6.0% for aromatic amines. The application of this SPME technique coupled with gas chromatography has been shown to be feasible for the rapid determination of fish freshness.
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 10/2004; 22(5):472-5.
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ABSTRACT: Solid-phase microextraction (SPME) using a novel fiber coated with 25,27-dihydroxy-26, 28-oxy(2',7'-dioxo-3',6'-diazaoctyl)oxy-p-tert-butylcalix[4]arene/hydroxy-terminated silicone oil has been introduced as a rapid and sensitive pretreatment technique coupled to gas chromatography-flame ionization detection (GC-FID) for the detection of aliphatic amines without derivatization. Due to the introduction of the polar amide bridge in calix[4]arene, the new fiber shows good selectivity and sensitivity to the polar aliphatic amines in addition to its high thermal stability (380 degrees C), solvent stability and good reproducibility between fibers. The extraction temperature, extraction time, pH, and ionic strength of the matrix sample were modified to allow for maximum sorption of the analytes onto the fiber. The method proposed in this study showed satisfactory linearity, precision and detection limits. Practical applicability was demonstrated through the determination of trimethylamine (TMA) in fish tissue. Mean recovery of 92.5% (n = 5) was obtained for the fish extracts and the relative standard deviation was 4.9% (n = 5). The results of fish freshness assay indicate the present method is a validated and simple procedure for the simultaneous determination of TMA in fish.
Journal of Chromatography 08/2004; 1041(1-2):1-9. · 4.53 Impact Factor
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ABSTRACT: Bridging including capping of calix[6]arene is not only an importantroute to synthesize new host molecules, but also an efficient route to reduce the mobility of conformationof calix[6]arene. This article reviews the syntheses, conformations and complexation behavior of this kindof host molecules.
Journal of Inclusion Phenomena 03/2003; 45(3):165-184. · 1.89 Impact Factor
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ABSTRACT: It was found that nano CaCO 3 played an interesting role in the reaction of p-tert-butylcalixarene with epoxides. In the presence of nano CaCO 3 , a monosubstituted calixarene, a b ring-opening product of epoxide, was obtained regioselectively in good yield. When normal CaCO 3 was used under the same conditions, the yield was less than 2%. The b ring-opening product of epichlorohydrin could convert to monoglycidyl calixarene by reacting with C 2 H 5 ONa in tetrahydrofuran at room temperature in moderate yield.
New Journal of Chemistry 12/2002; 26:1827. · 2.61 Impact Factor
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Tetrahedron Letters 46(36):6041-6044. · 2.68 Impact Factor
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ABSTRACT: After analyzing the status quo and development of the research of liquid membrane, we put forward the possibility and necessity of establishment of a new type of liquid membrane system, i.e. non-aqueous liquid membrane system. The new liquid membrane system was founded by replacing water in former water–oil–water or oil–water–oil system with organic solvents or fluid polymer. Two types of non-aqueous liquid membrane system were successfully founded. The first is the modification of water–oil–water system without carrier, and another is the modification of oil–water–oil system with carrier. The carriers were synthesized from alkenyl crown ether or azacrown ether by hydrosilylation of methyldichlorosilane, followed by condensation with α,ω-dihydroxypolydimethylsiloxane. The transport of benzene, xylenes, benzonitrile, cyclohexanol and propanediol in the non-aqueous liquid membrane systems were investigated. It was found that the carriers can facilitate the substance through a non-aqueous liquid membrane, and can transport 1,2-propanediol from the mixture of 1,2-propanediol and 1,3-propanediol slightly selectively.
Journal of Membrane Science 205:265-272. · 3.85 Impact Factor
