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1.
A new affinity adsorbent, using D-alanyl-D-alanine as ligand, has been prepared. The dipeptide immobilized on Activated CH-Sepharose
4B (D-Ala-D-Ala-AGA) bioselectively binds the glycopeptide antibiotics teicoplanin, vancomycin, ristocetin A (vancomycinlike
group of antibiotics) while it does not bind other antibiotics equally active on cell wall biosynthesis but with different
target sites, such as penicillin G, cephalosporin C, gardimycin, and bacitracin. Teicoplanin, vancomycin, and ristocetin A
have similar binding characteristics for the immobilized dipeptide, as indicated by equilibrium binding experiments. The affinity
constants of the three antibiotics for D-Ala-D-Ala-AGA is of the same order of magnitude (105 L mol-1) and the number of effective binding sites is similar for each antibiotic (6–7 μEq/mL of gel). The adsorption is biospecific
as no binding has been observed to immobilized L-alanyl-L -alanine.
D-Ala-D-Ala-AGA has been successfully used to purify teicoplanin from mixtures of different complexity and for concomitant
extraction and purification from fermentation liquors by both batch adsorption and column chromatography. The antibiotic can
be recovered from the resin in high yields by elution at pH 11. 相似文献
2.
The present work presents a study on the grafting of polyurethane onto chitosan. Prepolymers (polyurethanes) were obtained by condensation reactions between poly(ethylene glycol) of two different molar masses and isophorone diisocyanate. Characterization of graft copolymers was performed by infrared spectroscopy (IR) and 13C Nuclear Magnetic Resonance in the solid state (13C NMR). Evidences of grafting were obtained by IR from the absorbance increase of relative intensity of NH and CO bands, with respect to chitosan. The degree of NH2 substitution by urea groups observed from 0.12 to 0.59 was estimated from NMR data. The graft copolymers exhibited different solubility behavior as a function of degree of substitution, such as partial solubility, gelation or swelling in diluted acetic acid, and swelling in water, dimethylsulfoxide and acetic acid/sodium acetate. 相似文献
3.
Plévert J Sanchez-Smith R Gentz TM Li H Groy TL Yaghi OM O'Keeffe M 《Inorganic chemistry》2003,42(19):5954-5959
Six new zirconogermanates have been prepared under hydrothermal conditions using amines as bases. There are four new structure types (ASU-n) with a common motif of ZrGe(5). ASU-23 is a layered structure: ZrGe(3)O(8)(OH)F.[C(10)H(26)N(4)].H(2)O, space group P2(1)/n, a = 6.7957(8) A, b = 12.700(1) A, c = 24.293(3) A, beta = 97.936(2) degrees, V = 2076.4(4) A(3). ASU-24 is a pillared layered structure: Zr(3)Ge(6)O(18)(OH(2),F)(4)F(2).[C(6)H(18)N(2)].[C(6)H(17)N(2)](2).2H(2)O, space group P2(1)/n, a = 7.4249(3) A, b = 25.198(1) A, c = 11.3483(5) A, beta = 90.995(1) degrees, V = 2122.9(2) A(3). This material has the lowest framework density (FD) of any oxide material that we are aware of (FD = 8.48 metal atoms/nm(3)). Two other materials form three-dimensional open-frameworks, ASU-25: ZrGe(3)O(9).[C(3)H(12)N(2)], space group P112(1)/a, a = 13.1994(4) A, b = 7.6828(2) A, c = 11.2373(3) A, gamma = 91.233(3) degrees, V = 1139.29(5) A(3). The other is ASU-26: ZrGe(3)O(9).[C(2)H(10)N(2)], space group Pn, a = 13.7611(3) A, b = 7.7294(2) A, c = 11.2331(3) A, beta = 104.793(1) degrees, V = 1155.21(4) A(3). ASU-25 is related to the mineral umbite K(2)ZrSi(3)O(9).H(2)O. The germanium equivalent has been prepared through the inorganic route: K(2)ZrGe(3)O(9).H(2)O, space group P2(1)2(1)2(1), a = 13.6432(6) A, b = 7.4256(3) A, c = 10.3973(4) A, V = 1053.33(8) A(3). The structural relationships between ASU-25 and its inorganic counterpart are described. The thermal decomposition of the germanium umbite generated the cyclic trigermanate K(2)ZrGe(3)O(9), analogue of the mineral wadeite, crystallizing in the orthorhombic system, a = 7.076 A, b = 12.123 A, c = 10.451 A, V = 904.5 A(3). 相似文献
4.
Žaneta Mesíková Petra Šulcová M. Trojan 《Journal of Thermal Analysis and Calorimetry》2007,88(1):103-106
Phosphates belong to the extensive group
of inorganic pigments that are very often used in industry of plastics and
anticorrosive paints. Also, the powders of newberyite MgHPO4·3H2O
and α-pyrophosphate Mg2P2O7
can find the usage in this field. Thus, these compounds were the centre of
our attention. Newberyite and α-pyrophosphate were synthesized by the
method of gelling. Impact of various ways of synthesis, especially reaction
conditions, on the structural, thermal, physical and optical properties was
investigated. α-pyrophosphate was synthesized by the thermal decomposition
of newberyite at temperature around 500°C. Both powders are white color,
but the newberyite is the whitest one. The reaction pH particularly affected
the particle size distribution and optical properties. 相似文献
5.
Dibenzodioxadiselenafulvalene (DBOSF) was prepared and the cis and trans isomers were separated. X-ray crystallographic analysis revealed the presence of Se- - -H and O- - -H hydrogen bonds in both crystals. The electrochemical properties of cis- and trans-DBOSFs together with dibenzotetraoxafulvalene (DBTOF) and cis- and trans-dibenzodioxadithiafulvalenes were investigated by means of cyclic voltammetry and DFT calculation. The electron-donating ability and the stability of oxidized forms of DBOSFs are improved compared with those of DBTOF. 相似文献
6.
Yamada H Kuzuhara D Takahashi T Shimizu Y Uota K Okujima T Uno H Ono N 《Organic letters》2008,10(14):2947-2950
Linearly pi-expanded novel tetraanthroporphyrins with and without aromatic rings at the meso-positions were prepared quantitatively for the first time from the corresponding precursors by a retro-Diels-Alder reaction. 相似文献
7.
The synthesis of several meso-triaryl-subporphyrins, based on utilizing tripyrrolylborane as a precursor in a reaction with arylaldehydes (where aryl = phenyl, 4- and 3-pyridyl, tolyl, 4-methoxyphenyl, and 4-(trifluoromethyl)phenyl) under reflux in propionic acid, is reported. All of the compounds have been successfully characterized by 1H-, 13C-, and 13C-1H 2D NMR, electronic absorption, magnetic circular dichroism (MCD), IR, and fluorescence spectroscopy, together with cyclic (CV) and differential pulse (DPV) voltammetry. The X-ray structure of tris{(trifluoromethyl)phenyl}subporphyrin was found to be slightly domed and similar to that of the recently reported hexaethylsubtriazaporphyrin (Inorg. Chem. 2006, 45, 6148). The electronic absorption spectra of all of the subporphyrins contain intense Soret bands in the 370-380 nm region and weaker Q bands in the 420-550 nm region, which are at shorter wavelengths than those observed (at ca. 400-420 nm and ca. 450-650 nm, respectively) for tetrapyrrole porphyrins. The intensity of the Q00 band decreases as the meso-aryl groups become more electron withdrawing. These characteristics can be rationalized by using Gouterman's four-orbital model as a conceptual framework. The MCD bands observed in the Q band region of the subporphyrins (subPs) spectra consistently show a -ve/+ve intensity pattern in ascending energy, while, in contrast, the sign sequence of the bands observed in the Soret band region change dramatically depending on the nature of the aryl groups: from +ve/-ve in the case of the electron withdrawing 4-pyridyl, 4-(trifluoromethyl)phenyl and 3-pyridyl groups to -ve only for phenyl and -ve/+ve for the electron donating 4-tolyl and 4-methoxyphenyl groups. S1 fluorescence emission was observed in the 490-620 nm region. The quantum yields (phiF) in benzene (phiF = 0.10-0.12) are similar to that of metal-free tetraphenylporphyrin (H2TPP) (phiF = 0.11) but are somewhat lower in the case of ethanol (phiF = 0.06-0.07) due to the higher polarity. The redox potential differences observed between the first oxidation and reduction steps are in the 2.52-2.64 V range, which is larger than that of normal porphyrins (ca. 2.25 V). Molecular orbital (MO) calculations of these compounds help to provide an enhanced understanding of the spectroscopic and electrochemical properties. A byproduct of the synthesis was characterized using X-ray crystallography and a range of spectroscopic techniques. A subporphyrin mu-oxo dimer was prepared and characterized. 相似文献
8.
《Journal of Coordination Chemistry》2012,65(19):3432-3439
Thirteen new stannacyclododecane dithiocarbamate complexes have been prepared by reacting 12-chloro-12-n-butyl-1,11-dioxa-4,8-dithia-12-stannacyclododecane (1) and 12-chloro-12-n-butyl-1,4,8,11-tetrathia-12-stannacyclododecane (2) with pyrrolidine-, morpholine-, thiomorpholine-, piperidine-, piperazinebis-, and 3-pyrroline-carbodithioates, respectively, as well as with diethyl-dithiocarbamate. All complexes were characterized by elemental analyses, IR, EI-MS, and NMR (1H, 13C, and 119Sn) studies. The spectroscopic data suggest the replacement of the chlorides by the corresponding dithiocarbamates with monodentate coordination, leading to six-coordinate tin atoms in all the cases. 相似文献
9.
Beta-trifluoromethyl-meso-tetraphenylporphyrins were synthesized to investigate the electronic and steric effects of the trifluoromethyl groups on the macrocycle. Preparation of these novel porphyrins was carried out by copper-assisted trifluoromethylation of beta-tetrabromo-meso-tetraphenylporphyrin metal complexes and in situ generated CF3Cu. For comparison, the beta-methyl analogues were also prepared. Analysis of beta-trifluoromethylporphyrins by UV-vis, NMR, and cyclic voltammetry (CV) showed that the electron-withdrawing effects of the trifluoromethyl groups on the antipodal pyrroles required the macrocycle to take a fixed 18pi-electron pathway. UV-vis, CV, and molecular modeling studies suggest that the novel porphyrins are distorted following introduction of trifluoromethyl groups onto the pyrrolic beta-position of meso-tetraphenylporphyrin. The pK(a) difference of beta-tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin from that of DBU in CH2Cl2, obtained by spectrophotometric titration, affirms that it is one of the most electron-deficient porphyrins so far prepared. 相似文献
10.
Yan-Hong L Tong-Lai Z Jian-Guo Z Jin-Yu G Kai-Bei Y 《Molecules (Basel, Switzerland)》2005,10(8):978-989
In this paper we elected to nitrate p-xylene because this compound has only one mononitro- and trinitro- isomer. Trinitro-p-xylene was used as a starting material for the synthesis of other compounds in subsequent work. The mononitration of p-xylene can be easily carried out at 30 degrees C. Nitro-p-xylene is easily nitrated to dinitro-p-xylene at a temperature of 80 degrees C. The trinitro-p-xylene can be obtained at 120 degrees C. Single crystals of 2,3-dinitro-p-xylene and 2,3,5-trinitro-p-xylene were grown using the slow cooling method and we report the X-ray structure of the former. The thermal decomposition of the compounds was studied using differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) techniques and FT-IR. The target compounds were also characterized by (1)H-NMR, (13)C-NMR and MS. 相似文献
11.
12.
Robert C. Evers 《Journal of polymer science. Part A, Polymer chemistry》1970,8(2):563-576
A series of polyiminobenzothiazoles was synthesized by the polymerization of either 2,6-dichloro- or 2,6-diphenoxybenzobisthiazole with a number of aromatic diamines. A polymer was also obtained from the self-condensation of either 2-chloro- or 2-phenoxy-6-aminobenzothiazole. The polymers were characterized by their elemental analysis and infrared spectra. Thermogravimetric analysis, differential thermal analysis, and softening under load were used to evaluate their thermal properties. The polymers were found to be light tan to brown powders which showed only slight softening below their decomposition temperatures. Onset of breakdown under thermogravimetric analysis in a nitrogen atmosphere generally occurred at 375–400°C. The polymers were sparingly soluble in organic solvents and had inherent viscosities in the range of 0.11–0.55. 相似文献
13.
三羟甲基烷烃是用于醇酸树脂、聚氨酯树脂、表面活性剂、合成润滑油等的原料[1-3].三羟甲基十一烷(化学结构见图1)作为三羟甲基烷烃中直碳链最长的一员,不仅具有亲水性(分子中含三个亲水基),而且具有疏水性(含一个长直碳链亲油基),因此可用作表面活性剂.不仅如此,与同样用作乳化剂的一般高级脂肪醇(如十六烷醇)相比,可以在化妆品用的乳液中加入三羟甲基十一烷作乳化剂,以降低乳液的黏度,防止乳液中由于大量加入高级脂肪醇而导致产品黏度过高以至不能在皮肤上被充分涂抹开的状况发生[4].为制备智能芳香缓释型聚氨酯微胶囊壳材[5],需要设计聚氨酯的分子结构中含有能与相变石腊和油溶性香料有良好相容性的疏水链(三羟甲基十一烷与六亚甲基二异氰酸酯的加成物).因此,本文合成并表征了三羟甲基十一烷. 相似文献
14.
Linear polyamides having viscosities in the range of 0.12–0.41 dl/g have been prepared from bisbenzoyl propionic acids and aromatic diamines by low temperature solution polycondensation in 80–85% yield. Their solubility characteristics were studied in various solvents e.g. DMF, DMAC, HMPT, H2SO4. These polyamides are amorphous in nature; their densities range from 1.2 to 1.8 g/cm3. Their thermal properties were examined by TGA and DTA. The two stage decomposition phenomenon observed in TGA is in agreement with the DTA results. The integral procedural decomposition temperatures were calculated and found to exceed 250 in almost all cases. 相似文献
15.
A versatile synthetic method has been developed to incorporate photochromic azobenzene moieties into tetraphenylporphyrin frameworks in an orthogonal fashion, positioning the phenylazo substituents above and below the plane of the macrocycle. Surprisingly, photoisomerization is completely suppressed in the resulting azobenzene-confined porphyrins. 相似文献
16.
The simple Lewis acid–base adduct Me3Ga←Sb(SiMe3)3 (1) was prepared by the reaction of Me3Ga and Sb(SiMe3)3. Dehalosilylation reaction between Me2GaCl and Sb(SiMe3)3 in 1:1 mol ratio yields the trimeric [Me2GaSb(SiMe3)2]3 (2). 1 and 2 were fully characterized by mass and NMR spectroscopy. In addition, the solid state structure of compound 2 was determined by single crystal X-ray diffraction. 相似文献
17.
苯乙烯-丙烯酸酯-丙烯腈三元共聚物的合成及表征 总被引:1,自引:0,他引:1
在可控核聚变领域,惯性约束聚变(ICF)用空心靶球的研究[1-3]十分活跃。以聚苯乙烯为基材制备ICF有机物空心靶球已有广泛的研究,微球的制备技术、工艺等都已相当成熟,但聚苯乙烯阻气性差,难以阻挡氢同位素的扩散,不能满足ICF靶球的需要。目前应用比较好的ICF靶球制备条件极为苛刻,工艺复杂[4]。丙烯腈、丙烯酸酯、偏二氯乙烯、醋酸乙烯酯等一类单体的均聚物都有较好的阻气性[5],本文探讨苯乙烯与丙烯腈、丙烯酸酯类单体的共聚方法,研究了共聚物的一些基本性能。1 实验部分1 1 试剂及仪器苯乙烯、丙烯腈、丙烯酸甲酯、丙烯酸丁酯均… 相似文献
18.
Amit L. Sharma Manju Gerard Rahul Singhal B. D. Malhotra S. Annapoorni 《Applied biochemistry and biotechnology》2001,96(1-3):155-165
Poly(2-fluoroaniline) was prepared by both chemical and electrochemical polymerization in acidic medium. Characterization
of poly(2-fluoroaniline) was accomplished experimentally using ultraviolet-visible, Fourier transform infrared, differential
scanning calorimetry, thermal gravimetric analysis, and X-ray diffraction techniques, respectively. Scanning electron microscopy
studies revealed globular morphology of chemically synthesized poly(2-fluoroaniline). The cyclic voltammetric studies revealed
diffusion-controlled phenomenon in electrochemically synthesized poly(2-fluoroaniline). 相似文献
19.