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Tiny azacryptand 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane (L) upon reaction with 48% hydrobromic acid (containing <0.05% chloride contamination) forms hexabromide salt (1). Single crystal X-ray crystallographic investigation of the hexaprotonated bromide (1) shows no guest encapsulation inside the tiny cage. This bromide salt 1 with an empty proton cage has been utilized as the receptor for encapsulation of chloride (2) and fluoride (3). Crystallographic results of mixed chloride/bromide (2) and fluoride/bromide (3) complexes of L are examined, which show monotopic recognition of chloride in the case of 2 and fluoride in the case of 3 inside the proton cage with five bromide and three water molecules outside the cavity. Single crystals obtained from an experiment on mixed anionic system (chloride and fluoride), 1 shows selective encapsulation of fluoride, which supports the formation of complex 3 and crystals obtained upon treatment of 2 with tetrabutyl ammonium fluoride also yields complex 3. In a separate reaction between L and 49% hydrobromic acid containing higher chloride contamination (<0.2%) forms chloride/bromide salt (2). 1H NMR studies of 1 with sodium chloride and fluoride support the encapsulation of the respective anions inside the proton cage....
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Tiny azacryptand 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane (L) upon reaction with 48% hydrobromic acid (containing <0.05% chloride contamination) forms hexabromide salt (1). Single crystal X-ray crystallographic investigation of the hexaprotonated bromide (1) shows no guest encapsulation inside the tiny cage. This bromide salt 1 with an empty proton cage has been utilized as the receptor for encapsulation of chloride (2) and fluoride (3). Crystallographic results of mixed chloride/bromide (2) and fluoride/bromide (3) complexes of L are examined, which show monotopic recognition of chloride in the case of 2 and fluoride in the case of 3 inside the proton cage with five bromide and three water molecules outside the cavity. Single crystals obtained from an experiment on mixed anionic system (chloride and fluoride), 1 shows selective encapsulation of fluoride, which supports the formation of complex 3 and crystals obtained upon treatment of 2 with tetrabutyl ammonium fluoride also yields complex 3. In a separate reaction between L and 49% hydrobromic acid containing higher chloride contamination (<0.2%) forms chloride/bromide salt (2). 1H NMR studies of 1 with sodium chloride and fluoride support the encapsulation of the respective anions inside the proton cage.
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A kind of strong anion exchanger (SAX) was prepared with chloromethylstyrene encapsulated silica. This strong anion silica column has superior ability for the separation of anions, organic acids and also the mixture of them. Using...
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A kind of strong anion exchanger (SAX) was prepared with chloromethylstyrene encapsulated silica. This strong anion silica column has superior ability for the separation of anions, organic acids and also the mixture of them. Using this strong anion exchanger, the sulfonic acids can be separated. With gradient elution, the separation of petroleum mono- and di- sulfonates in Yumen sample can be also well obtained. This anion exchanger's stability has been studied. After continuous use for three months the carbon and nitrogen contents and the chromatographic behavior of the exchanger were unchanged.
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The relative affinity of the recently synthesized receptor bambus[6]uril (BU[6]) towards halides in encapsulation processes was theoretically studied by means of M06-2X and B3LYP calculations. The gas-phase results do not follow t...
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The relative affinity of the recently synthesized receptor bambus[6]uril (BU[6]) towards halides in encapsulation processes was theoretically studied by means of M06-2X and B3LYP calculations. The gas-phase results do not follow the affinity experimentally observed in solution, as the largest encapsulation energy was obtained for fluoride, and the smallest one for iodide. Nevertheless, this finding is in agreement with the gas phase hydrogen bond energies determined for the CH_4?X- complexes, X=F~-, Cl~-, Br~-, I~-. The structural changes experienced by the receptor when the halide is inside decrease as we move from fluoride to iodide. Thus, the relative affinity is due to a balance between the hydrogen-bond energies between the methine groups inside the cavity and the anions (CH?X-) and the deformation of the receptor induced by the anion. When solvents effects are considered, the affinity of BU[6] for halides is in line with experimental evidence. In effect, the difference between the δG298{ring operator} computed for iodide and bromide is 1kcal/mol, just 0.5kcal/mol smaller than the experimental value. The effect of the counter ion was evaluated using Na~+, but inclusion of the latter worsens the agreement with experiment. Finally, we discuss methodological problems observed for the BU[6]·X~- complexes.
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Two simple tris(2-aminoethyl)amine (tren)-based electron-donating p-methyl (L_1) and p-methoxy (L_2)-substituted tristhioureas have been extensively studied with various anions. The X-ray diffraction studies reveal that in the cas...
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Two simple tris(2-aminoethyl)amine (tren)-based electron-donating p-methyl (L_1) and p-methoxy (L_2)-substituted tristhioureas have been extensively studied with various anions. The X-ray diffraction studies reveal that in the case of both receptors L_1 and L_2, halide anions (F~-, Cl~- and Br-) are encapsulated into the tripodal cavity of the receptors with 1:1 stoichiometry and anions such as SO~(2-) 4 and HPO~(2-) 4 form dimeric capsular assemblies of the receptors with 1:2 stoichiometry. The solution-state binding and encapsulation of anions have also been confirmed by ~1H NMR titration and 2D NOESY NMR experiments. The 1H NMR titration experiments show that receptor L_1 is able to deprotonate HSO~- _4, HCO~- _3 and H 2PO~- _4 in solution, which was further verified with the addition of tetrabutylammonium hydroxide. On the other hand, receptor L_2 failed to deprotonate the hydrogenated oxy-anions in solution.
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Fish oil microcapsules were successfully prepared from fish oil-in-water emulsions using chitosan as shell material and anionic surfactants sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulfonate (SDBS), sodium cholate (chol...
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Fish oil microcapsules were successfully prepared from fish oil-in-water emulsions using chitosan as shell material and anionic surfactants sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulfonate (SDBS), sodium cholate (cholate), and sodium deoxycholate (DOC) as emulsifiers. The type of emulsifier influenced the physicochemical characteristics of the prepared microcapsules to different extents. The microcapsules formed with DOC showed the least mean effective diameter (MED) of 500 nm. Emulsion formed with DOC exhibited the smallest MED of 100 nm. The emulsions showed negative zeta potential values which became positive after encapsulation with chitosan. The surfactants showed little influence on thermal stability. Microcapsule suspensions showed creaming over storage. Fish oil at higher loading in SDS microcapsules showed higher primary and secondary oxidation. All microcapsules showed sustained release but the values varied depending upon the surfactants. The emulsion and microcapsules formed with DOC showed better morphology and stability despite its lower loading and encapsulation efficiency.
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The reaction of uranyl nitrate with cucurbit[6] uril (CB6) and carboxylic or sulfonic ligands under hydrothermal conditions and in the presence of additional metal cations (KI or Ce-III) or cosolvents provided four complexes, whic...
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The reaction of uranyl nitrate with cucurbit[6] uril (CB6) and carboxylic or sulfonic ligands under hydrothermal conditions and in the presence of additional metal cations (KI or Ce-III) or cosolvents provided four complexes, which were crystallographically characterized. The compound [(UO2) 2 K-2(CB6)(adc)(2)(NO3)(2)(H2O)(2)]center dot 5H(2)O (1), where H2adc is 1,3-ada-mantanedicarboxylic acid, crystallizes in the form of a central K-2(CB6)(2+) column surrounded by two one-dimensional (1D) polymeric UO2(adc)(NO3)(-) chains attached to the column by nitrate bridges, with a perfect match of the repeat lengths in the two subunits. The longer 1,3-adamantanediacetic acid (H2adac) gives the complex [(UO2)(2)(adac)(2)(HCOOH)(2)]center dot CB6 center dot 6H(2)O (2), in which the 1D uranyl-containing polymer and columns of CB6 molecules form a layered arrangement held by weak CH center dot center dot center dot O hydrogen bonds. The complex formed with the dipotassium salt of methanedisulfonic acid (K(2)mds), [(UO2)(2)K-2(CB6)(mds)(2)-(OH)(2)(H2O)(8)]center dot 4H(2)O (3), is a 1D polymer, in which K-2(CB6)(2+) units are connected to one another by doubly hydroxide-bridged uranyl dimers in which the disulfonates are terminal, chelating ligands; connection between the two subunits is solely through potassium oxo-bonding to uranyl. The complex [(UO2)(2)Ce-2-(CB6)(C2O4)(3)(NO3)(4)(H2O)(6)]center dot 2H(2)O (4) is a 1D polymer containing bridging oxalate ligands formed in situ, in which CB6 is coordinated to the lanthanide cations only; one nitrate ligand and one water ligand, hydrogen-bonded to each other, are included in the CB6 cavity, with the possible occurrence of interactions between nitrate oxygen atoms and ureido carbon atoms.
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Synthesis of molecular containers capable of incorporating multiple fullerenes remains challenging. Reported here is that room-temperature mixing of metal ions with W-shaped bispyridine ligands featuring polyaromatic panels result...
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Synthesis of molecular containers capable of incorporating multiple fullerenes remains challenging. Reported here is that room-temperature mixing of metal ions with W-shaped bispyridine ligands featuring polyaromatic panels results in the quantitative formation of a peanut-shaped M2L4 capsule. The capsule reversibly converts into two molecules of an ML2 double tube in response to changes in the solvent. Notably, the capsule allows the incorporation of two fullerene molecules into the connected two spherical cavities at room temperature. The close proximity yet non-contact of the encapsulated C-60 molecules, with a separation of 6.4 angstrom, was revealed by X-ray crystallographic analysis. The resultant, unusual fullerene dimer undergoes sequential reduction within the capsule to generate (C-60(.-))(2), C-60(.-).C-60(2-), and (C-60(2-))(2) species. Furthermore, temperature-controlled stepwise incorporation of two C-60 molecules into the capsule is demonstrated.
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Tris-(2-aminoethyl) amine (Tren) based tripodal thiourea (L-1 and L-2) and urea (L-3) receptors are reported. L-1 efficiently fix atmospheric CO2 as CO32- in presence of the hydroxide ion. Both L-1 and L-2 encapsulate SO42- anion ...
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Tris-(2-aminoethyl) amine (Tren) based tripodal thiourea (L-1 and L-2) and urea (L-3) receptors are reported. L-1 efficiently fix atmospheric CO2 as CO32- in presence of the hydroxide ion. Both L-1 and L-2 encapsulate SO42- anion by forming 2:1 host-guest capsular assemblies through hydrogen-bond activated proton transfer. Both L-1 and L-2 show strong anion binding in their neutral form through strong non-covalent interactions. On contrary, tris-urea ligand L-3 recognizes SiF62- and Br- trapped cyclic/acyclic anion-water network assemblies outside the protonated receptor cavities in presence of corresponding inorganic acids HF and HBr respectively.
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摘要 :Graphical abstractDisplay OmittedAbstractHypothesisGemini pyridinium-based amphiphiles can play a triple role as: gold nanoparticles (AuNPs) synthesis facilitator, particle stabilizer and anion recognition centre. The so...
展开Graphical abstractDisplay OmittedAbstractHypothesisGemini pyridinium-based amphiphiles can play a triple role as: gold nanoparticles (AuNPs) synthesis facilitator, particle stabilizer and anion recognition centre. The so formed nanoparticles should be able to bind and release anionic drugs.ExperimentsWe describe (a) Synthesis, by a phase transfer method, of both new organic media and water soluble AuNPs using gemini-type surfactants based on bis-pyridinium salts as ligands, acting as transfer agents into organic media and also as nanoparticle stabilizers, (b) Examination of their stability in solution, (c) Chemical and physical characterization of the nanoparticles, (d) Toxicity data concerning both the bis-pyridinium ligands and the bis-pyridinium coated nanoparticles, and (e) Study of their ability for delivering anionic pharmaceuticals such as ibuprofen and piroxicam.收起
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Despite remarkable progress in the research of both viral and nonviral gene delivery vectors, the drawbacks in each delivery system have limited their clinical applications. Therefore, one of the concepts for developing novel vect...
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Despite remarkable progress in the research of both viral and nonviral gene delivery vectors, the drawbacks in each delivery system have limited their clinical applications. Therefore, one of the concepts for developing novel vectors is to overcome the limitations of individual vectors by combining them. In the current study, adenoviral vectors were formulated with anionic liposomes to protect them from neutralizing antibodies and to improve their transduction efficiency in Coxsackievirus-adenovirus receptor (CAR) deficient cells. A calcium-induced phase change method was applied to encapsulate adenovirus 5 (Ad5) into anionic liposomes to formulate the complexes of Ad5 and anionic liposomes (Ad5-AL). Meanwhile, the complexes of Ad5 and cationic liposomes (Ad5-CL) were also prepared as controls. LacZ gene expression in CAR overexpressing cells (A549) and CAR deficient cells (CHO and MDCK) was measured by either qualitative or quantitative detection. Confocal laser scanning microscopy was performed to determine intracellular location of Ad5 after their infection. Human sera with a high titer of antiadenovirus antibody were used to assess the neutralizing antibody protection ability of the complexed vectors. Accompanying the enhanced gene expression, a high ability to introduce Ad5 into cytoplasm and nucleus mediated by Ad5-AL was also observed in CAR deficient cells. Additionally, antibody neutralizing assay indicated that neutralizing serum inhibited naked Ad5 and Ad5-CL at rather higher dilution than Ad5-AL, which demonstrated Ad5-AL was more capable of protecting Ad5 from neutralizing than Ad5-CL. In conclusion, anionic liposomes prepared by the calcium-induced phase change method could significantly enhance the transduction ability of Ad5 in CAR deficient cells.
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