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991.
992.
New 3 D Tubular Porous Structure of an Organic–Zincophosphite Framework with Interesting Gas Adsorption and Luminescence Properties
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Prof. Chih‐Min Wang Dr. Li‐Wei Lee Tsung‐Yuan Chang Bing‐Lun Fan Chih‐Ling Wang Prof. Hsiu‐Mei Lin Prof. Kuang‐Lieh Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16099-16102
A new 3D tubular zinc phosphite, Zn2(C22H22N8)0.5(HPO3)2?H2O ( 1 ), incorporating a tetradentate organic ligand was synthesized under hydro(solvo)thermal conditions and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 is the first example of inorganic zincophosphite chains being interlinked through 1,2,4,5‐tetrakis(imidazol‐1‐ylmethyl)benzene to form a tubular porous framework with unusual organic–inorganic hybrid channels. The thermal and chemical stabilities, high capacity for CO2 adsorption compared to that for N2 adsorption, and interesting optical properties of LED devices fabricated using this compound were also studied. 相似文献
993.
Synthesis of organic‐inorganic hybrid gels by means of thiol‐ene and azide‐alkene reactions
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Naofumi Naga Hitomi Nagino Hidemitsu Furukawa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(14):2229-2238
Organic–inorganic hybrid gels have been synthesized from a multi‐vinyl functional cyclic siloxane, 1,3,5,7‐tetravinyltetramethylcyclotetrasiloxane (TVMCTS), or a cubic silsesquioxane, octavinyloctasilasesquioxane (PVOSS), and α,ω‐dithiol compounds, 1,6‐hexanedithiol (HDT), 1,10‐decanedithiol (DDT), using thiol‐ene reaction in toluene. The network structure of the resulting gels, mesh size and mesh size distribution, was quantitatively characterized by means of a scanning microscopic light scattering (SMILS). The gels obtained from TVMCTS‐HDT formed homogeneous network structure with 1.5–1.6 nm mesh. Relaxation peaks derived from large clusters and/or micro gels were detected in the SMILS analysis of the TVMCTS‐DDT, PVOSS‐HDT, and PVOSS‐DDT gels besides those from the small meshes. The organic–inorganic hybrid gels were also synthesized from TVMCTS, PVOSS with α,ω‐diazide compounds, 1,6‐hexanediazide (HDA), 1,10‐decanediazide (DDA), using azide‐alkene reaction in toluene. All the gels obtained with the azide‐alkene reaction formed the homogeneous network structure. Enthalpy relaxation at the glass transition of the dried samples was detected by differential scanning calorimetry to study the network uniformity of the original gels. The gels synthesized by the azide‐alkene reaction showed larger enthalpy than the gels synthesized by the thiol‐ene reaction, indicating homogeneous network structure in the former gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2229–2238 相似文献
994.
Choline phosphate(CP) as a novel zwitterion possesses specific and excellent properties compared with phosphorylcholine(PC), as well as its polymer, such as poly(2-(methacryloyloxy)ethyl choline phosphate)(PMCP), has been studied extensively due to its unique characteristics of rapid cellular internalization via the special quadrupole interactions with the cell membrane. Recently, we reported a novel PMCP-based drug delivery system to enhance the cellular internalization where the drug was conjugated to the polymer via reversible acylhydrazone bond. Herein, to make full use of this feature of PMCP, we synthesized the diblock copolymer poly(2-(methacryloyloxy)ethyl choline phosphate)-b-poly(2-(diisopropylamino)ethyl methacrylate)(PMCP-b-PDPA), which could self-assemble into polymersomes with hydrophilic PMCP corona and hydrophobic membrane wall in mild conditions when the p H value is ≥ 6.4. It has been found that these polymersomes can be successfully used to load anticancer drug Dox with the loading content of about 11.30 wt%. After the polymersome is rapidly internalized by the cell with the aid of PMCP, the loaded drug can be burst-released in endosomes since PDPA segment is protonated at low p H environment, which renders PDPA to transfer from hydrophobic to hydrophilic,and the subsequent polymersomes collapse thoroughly. Ultimately, the "proton sponge" effect of PDPA chain can further accelerate the Dox to escape from endosome to cytoplasm to exert cytostatic effects. Meanwhile, the cell viability assays showed that the Dox-loaded polymersomes exhibited significant inhibitory effect on tumor cells, indicating its great potential as a targeted intracellular delivery system with high efficiency. 相似文献
995.
Ali Ramazani Issa Amini Abdolhossain Massoudi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2373-2376
The protonation of the highly reactive 1:1 intermediates, produced in the reaction of triphenylphosphine and dialkyl acetylenedicarboxylates, by 1,1-binaphthyl-2,2′-diol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction to produce the corresponding stabilized phosphonium ylides. Dipotassium hydrogen phosphate powder was found to catalyze the conversion of the stabilized phosphonium ylides to alkyl 2-(2-alkoxy-2-oxoethyl)dinaphtho[2,1-d:1,2-f][1,3]-dioxepin-2-carboxylates under solvent-free conditions using microwave (0.6 KW, 3 min) and thermal (100°C, 60 min) conditions. 相似文献
996.
Ewa Szefer Krzysztof Stafin Agnieszka Leszczyska Paulina Zajc Edyta Hebda Konstantinos N. Raftopoulos Krzysztof Pielichowski 《Journal of Polymer Science.Polymer Physics》2019,57(17):1133-1142
A top‐down approach is applied for the production of polyurethane (PU)–polyhedral oligomeric silsesquioxane (POSS) nanocomposites, namely melt blending. As opposed to the typical chemical incorporation during synthesis, a POSS moiety with two hydroxyl groups is melt blended into a commercial thermoplastic polyurethane with mass fraction up to 2 wt %. POSS disperses in the matrix in submicrometer‐sized crystals, as well as in length scale of few tens of nanometers, in the bulk. Phase separation of the produced composites was studied by both standard dynamic and isothermal annealing experiments. In an approach rare in the literature, the dynamics of phase separation is discussed based on isothermal differential scanning calorimetry curves recorded during annealing. The blended‐in nanoparticles affect the micromorphology in a complicated manner, dependent on the intrinsically complex phase separation mechanism of PU. At higher temperatures, POSS slows down the phase separation, whereas at lower ones, it enhances and accelerates it. POSS decreases the mechanical modulus of the final material, presumably as a result of changes in the microphase separation. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1133–1142 相似文献
997.
Dr. Tobias Wehner Dr. Joachim Heck Prof. Dr. Claus Feldmann Prof. Dr. Klaus Müller-Buschbaum 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16630-16638
The luminescence of the inorganic–organic hybrid nanoparticles ZrO(MFP) (MFP=methylfluorescein phosphate) and ZrO(RP) (RP=resorufin phosphate) was modified by addition of different rare earth halides LnCl3. The resulting composite materials form dispersible nanoparticles that exhibit modified nanoparticle fluorescence depending on the rare earth ion. The resulting chromaticity of the luminescence is further variable by the employment of different solvents for ZrO(MFP)-based composite systems. The strong solvatochromic effect of the MFP chromophore leads to different luminescence chromaticities of the composite materials between green, yellow, and blue in THF, toluene, and dichloromethane, respectively. The luminescence of ZrO(RP)-based composite particles can be modified between the red and blue spectral regions in dependence on the applied reaction temperature. Beside a luminescence shift that is derived from nanoparticle modification by LnCl3, a strong turn-on effect of ZrO(RP) particles results after contact with different Brønsted acids and bases in combination with a respective chromaticity shift. Both effects enable the potential employment of such particles as highly sensitive optical pH sensors. 相似文献
998.
Replacement of Water Molecules in a Phosphate Binding Site by Furanoside‐Appended lin‐Benzoguanine Ligands of tRNA‐Guanine Transglycosylase (TGT)
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Dr. Luzi J. Barandun Frederik R. Ehrmann Daniel Zimmerli Dr. Florian Immekus Maude Giroud Claudio Grünenfelder Dr. W. Bernd Schweizer Dr. Bruno Bernet Michael Betz Prof. Dr. Andreas Heine Prof. Dr. Gerhard Klebe Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):126-135
The enzyme tRNA‐guanine transglycosylase has been identified as a drug target for the foodborne illness shigellosis. A key challenge in structure‐based design for this enzyme is the filling of the polar ribose‐34 pocket. Herein, we describe a novel series of ligands consisting of furanoside‐appended lin‐benzoguanines. They were designed to replace a conserved water cluster and differ by the functional groups at C(2) and C(3) of the furanosyl moiety being either OH or OMe. The unfavorable desolvation of Asp102 and Asp280, which are located close to the ribose‐34 pocket, had a significant impact on binding affinity. While the enzyme has tRNA as its natural substrate, X‐ray co‐crystal structures revealed that the furanosyl moieties of the ligands are not accommodated in the tRNA ribose‐34 site, but at the location of the adjacent phosphate group. A remarkable similarity of the position of the oxygen atoms in these two structures suggests furanosides as a potential phosphate isoster. 相似文献
999.
Phosphoester Hydrolysis: The Incoming Substrate Turns the Bridging Hydroxido Nucleophile into a Terminal One
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Dr. Eric Gouré Dr. Michaël Carboni Angélique Troussier Colette Lebrun Dr. Jacques Pécaut Jean‐François Jacquot Patrick Dubourdeaux Dr. Martin Clémancey Dr. Geneviève Blondin Dr. Jean‐Marc Latour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8064-8068
Identifying the active nucleophile in hydrolysis reactions catalyzed by binuclear hydrolases is a recurrent problem and a matter of intense debate. We report on the phosphate ester hydrolysis by a FeIIIFeII complex of a binucleating ligand. This complex presents activities in the range of those observed for similar biomimetic compounds in the literature. The specific electronic properties of the FeIIIFeII complex allowed us to use 1H NMR and Mössbauer spectroscopies to investigate the nature of the various species present in the solution in the pH range of 5–10. Both techniques showed that the hydrolysis activity is associated to a μ‐hydroxido FeIIIFeII species. Further 1H NMR experiments show that binding of anions or the substrate changes this bonding mode suggesting that a terminal hydroxide is the likely nucleophile in these hydrolysis reactions. This view is further supported by the structure determination of the hydrolysis product. 相似文献
1000.
The bacterial metabolite and potent innate immune modulator d-glycero-β-d-manno-heptose-1,7-bisphosphate (HBP) and its α-configured counterpart d-glycero-α-d-manno-heptose-1,7-bisphosphate were synthesized via stereoselective anomeric phosphorylation of the peracetylated d,d-heptose 7-dibenzylphosphate by exploiting different nucleophilicity of equatorial and axial lactols in the d-manno-series. We also report a novel approach for anomeric phosphorylation using modified Mitsunobu reaction conditions and provide the first full structural characterization of HBP. The first chemical synthesis of HBP offers access to an anomerically pure structurally defined probe for biological studies and to a lead compound operating as a powerful stimulator of intracellular signaling for possible therapeutic immunomodulation. 相似文献