id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
|---|---|---|
11418770 | Using surface-bound rubidium ions for protein phasing. | Rubidium is a monovalent metal that can be used as a counterion in protein solutions. X-ray anomalous scattering from rubidium ions bound to the protein surface was used for phasing of the crystal structure of the hsp60 apical domain from Thermus thermophilus. Multiple-wavelength anomalous dispersion (MAD) data were co... |
11418753 | Rapid neutron-diffraction data collection for hydrogen-bonding studies: application of the Laue diffractometer (LADI) to the case study zinc (tris)thiourea sulfate. | The successful application of the newly developed image-plate neutron Laue diffractometer (LADI) at the Institut Laue-Langevin (ILL), Grenoble, France, for rapid hydrogen-bonding characterization is reported. The case study concerns the promising non-linear optical material zinc (tris)thiourea sulfate (ZTS), which cont... |
11425343 | Biochemical, electron microscopic and immunohistological observations of cationic detergent-extracted cells: detection and improved preservation of microextensions and ultramicroextensions. | <h4>Background</h4>Filopodia, retraction fibers and microvilli, are fragile microextensions of the plasma membrane that are easily damaged by mechanical force during specimen preparation for microscopy. To preserve these structures for electron microscopy glutaraldehyde is generally used, but it often causes antigen ma... |
11390964 | Kinetics and mechanism of DNA uptake into the cell nucleus. | Gene transfer to eukaryotic cells requires the uptake of exogenous DNA into the cell nucleus. Except during mitosis, molecular access to the nuclear interior is limited to passage through the nuclear pores. Here we demonstrate the nuclear uptake of extended linear DNA molecules by a combination of fluorescence microsco... |
11390960 | Corneal collagen fibril structure in three dimensions: Structural insights into fibril assembly, mechanical properties, and tissue organization. | The ability of the cornea to transmit light while being mechanically resilient is directly attributable to the formation of an extracellular matrix containing orthogonal sheets of collagen fibrils. The detailed structure of the fibrils and how this structure underpins the mechanical properties and organization of the c... |
29712222 | Self-Assembly of Uniform Spherical Aggregates of Magnetic Nanoparticles through π-π Interactions. | Nanoparticles of Fe<sub>3</sub> O<sub>4</sub> coated with 2-carboxyterthiophene (TTP-COOH) self-assemble through π-π interactions to form uniform transparent microspheres. The interaction between individual particles is relatively weak and the spherical aggregates can be destroyed by sonication to leave the monodispers... |
29712221 | Modular Self-Assembly of a Microporous Solid Based upon Mercuracarborand-4 and a New Bonding Motif. | Modular units of Li<sub>2</sub> [B-octaiodo-12-mercuracarborand-4⋅I<sub>2</sub> ] (Li<sub>2</sub> [(HgC<sub>2</sub> B<sub>10</sub> H<sub>8</sub> I<sub>2</sub> )<sub>4</sub> ⋅I<sub>2</sub> ]) self-assemble forming infinite one-dimensional chains and microporous channels in the solid state. Self-assembly is directed by a... |
29712220 | Polymerization of Ureidopyrimidinone-Functionalized Olefins by Using Late-Transition Metal Ziegler-Natta Catalysts: Synthesis of Thermoplastic Elastomeric Polyolefins. | Mimicking nature: The central mechanisms of living organisms depend on the formation of specific hydrogen bonds. Advances in the areas of catalysis and supramolecular chemistry have been applied here for the synthesis of a novel class of elastomeric polyolefins with properties dependent upon strong intermolecular hydro... |
29712219 | Polygons and Faceted Polyhedra and Nanoporous Networks. | Small rhombihexahedra and small cubicuboctahedra, namely faceted polyhedra, form the basis of two novel low-density framework solids that are afforded by the self-assembly of molecular squares only or molecular squares and triangles, respectively. |
29712218 | Novel Templating Effect in the Macrocyclization of Functionalized Diynes by Zirconocene Coupling. | A zirconocene double act: The course of zirconocene-mediated macrocyclization is controlled by templating effects. In macrocyclizations of bipyridine-containing diynes, the zirconocene reagent [Cp<sub>2</sub> Zr(py)(Me<sub>3</sub> SiC≡SiMe<sub>3</sub> )] (1; py=pyridine) acts as both coupling and templating agent. Thus... |
29712202 | Macrocycles within Macrocycles: Cyclen, Cyclam, and Their Transition Metal Complexes Encapsulated in Cucurbit[8]uril. | Reminiscent of Russian Matrioshka dolls, tetraazamacrocycles (1,4,7,10-tetraazacyclododecane (cyclen) and 1 , 4 , 8 , 11 - tetraazacyclotetradecane (cyclam)) and their transition metal complexes are encapsulated in the cavity of cucurbit[8]uril (CB[8]). The X-ray crystal structure of the [Cu(cyclen)] in CB[8] complex (... |
29712197 | Self-Assembly of Nanometer-Scale Secondary Building Units into an Undulating Two-Dimensional Network with Two Types of Hydrophobic Cavity. | A series of bowls separated by hour-glass-shaped channels characterizes the structure of the undulating two-dimensional coordination polymer that is prepared from a nanoscale secondary building unit (nSBU), which is formed by four square metal(II)carboxylate SBUs that have 1,3-benzenedicarboxylate units as 120° spacers... |
29712191 | A Rationally Designed NH<sub>4</sub><sup>+</sup> Receptor Based on Cation-π Interaction and Hydrogen Bonding. | A cage-type receptor binds an NH<sub>4</sub><sup>+</sup> ion by cation-π interactions and hydrogen bonding with high sensitivity and selectivity, comparable or even superior to those of the natural antibiotic nonactin over a wide pH range. The high performance, low cost, and easy synthesis may offer practical applicati... |
29712186 | Self-Assembling Cyclic Peptide Cylinders as Nuclei for Crystal Engineering. | A supramolecular recognition interface is formed through the self-assembly of cyclic D,L-peptides. Phenyl-phenyl interactions direct the solid-state organization of dimeric peptide cyclo[(-L-Phe-D-<sup>Me</sup> N-Ala-L-hPhe-D-<sup>Me</sup> N-Ala)<sub>2</sub> ] (1) by forming clusters of edge-to-face contacts between di... |
29711845 | Self-Assembly and Manipulation of Crown Ether Phthalocyanines at the Gel-Graphite Interface. | Two "face-on" phases and one "edge-on" lamellar phase comprised of self-assembled structures of phthalocyanines have been visualized by scanning tunneling microscopy (STM) at the gel-graphite interface. The switching between the phases can be stimulated with the microscope tip with a resolution on the molecular scale. ... |
29711835 | Cyclic Hexamer with a Cubic Cavity: Crystal Structure of [{Rh(6-Purinethione Ribosido)(Cp*)}<sub>6</sub> ](CF<sub>3</sub> SO<sub>3</sub> )<sub>6</sub>. | The stereoselective formation of a pseudo-S<sub>6</sub> hexamer resulted from the self-assembling reaction between [Rh(Cp*)(H<sub>2</sub> O)<sub>3</sub> ]<sup>2+</sup> and 6-purinethione riboside (see left structure; Cp*=C<sub>5</sub> Me<sub>5</sub> ). The schematic representation (right) shows the direction of the coo... |
29711833 | Correlating Electron Transport and Molecular Structure in Organic Thin Films. | A convenient experimental system is described, with which electron transport through structurally well-defined, 2-5 nm-thick, organic films can be examined. Two types of junction J have been studied in which self-assembled monolayers (SAMs, for example, SAM(1) formed on Ag from aliphatic and aromatic thiols, and SAM(2)... |
29711829 | Metal Complexes of an N-Confused Calix[4]phyrin Derivative-The First X-ray Structure of an Organometallic Compound of Divalent Copper. | Rare organometallic complexes can be stabilized by using an N-confused system as a carbon ligand. A stable organocopper(II) compound of N-confused calix[4]phyrin has been characterized by X-ray crystallography. Complete π conjugation was found not to be a prerequisite for the formation of the metal-carbon bond. |
29711827 | Cesium- and Rubidium-Selective Redox-Active Bis(calix[4]diquinone) Ionophores. | The length of the bridging alkylene chain between two calix[4]diquinone moieties determines the selectivity of the receptors for Group 1 metal ions. These redox-active receptors exhibit remarkable selectivity preferences and substantial electrochemical recognition effects towards Cs<sup>+</sup> and Rb<sup>+</sup> ions.... |
29711822 | The Hg<sub>3</sub><sup>2+</sup> Group as a Framework Unit in a Host-Guest Compound: [Hg<sub>11</sub> As<sub>4</sub> ](GaBr<sub>4</sub> )<sub>4</sub>. | Pyramids in a mercury tunnel: Hg<sub>3</sub><sup>2+</sup> and Hg<sub>2</sub><sup>2+</sup> units form the tunnel walls of the novel inorganic supramolecular compound [Hg<sub>11</sub> As<sub>4</sub> ](GaBr<sub>4</sub> )<sub>4</sub> . This is the first three-dimensional framework that incorporates the subvalent mercury cl... |
23686958 | Selective adhesion, lipid exchange and membrane-fusion processes between vesicles of various sizes bearing complementary molecular recognition groups. | Equimolar mixtures of large unilamellar vesicles (LUVs) obtained from mixtures of egg lecithin and lipids containing complementary hydrogen bonding head groups (barbituric acid (BAR) and 2,4,6-triaminopyrimidine (TAP)) were shown to aggregate and fuse. These events have been studied in detail using electron microscopy ... |
23345739 | The role of solvent in protein folding and in aggregation. | We discuss features of the effect of solvent on protein folding andaggregation, highlighting the physics related to the particulate nature and the peculiar structure of the aqueous solvent, and the biological significance of interactions between solvent and proteins. To this purpose we use a generalized energy landscap... |
18968302 | Study on the supramolecular system of TAPP with cyclodextrins by polarography. | The interaction of cyclodextrins with meso- Tetrakis (4-N-trimethylaminobenzyl) porphyrin (TAPP) in 0.1 mol l(-1) phosphate buffer (pH 7.0, 20 degrees C) has been studied by polarography. The TAPP can form the 1:1 inclusion complex with Sulfobutylether-beta-cyclodextrin (SBE-beta-CD) and1:2 inclusion complexes with oth... |
11433436 | Strategies for the Construction of Supramolecular Compounds through Coordination Chemistry. | Synthetic organic chemists enjoy the luxury of having a large collection of reliable reactions at their disposal for preparing small molecules, mesoscopic structures, and polymers. Coordination chemists, on the other hand, are faced with the fact that transition metal chemistry, when normalized for the number of transi... |
11397453 | Purification and properties of a novel raw starch degrading-cyclodextrin glycosyltransferase from Klebsiella pneumoniae AS- 22. | A novel raw starch degrading alpha-cyclodextrin glycosyltransferase (CGTase; E.C. 2.4.1.19), produced by Klebsiella pneumoniae AS-22, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The specific cyclization activity of the pure enzyme preparation was 523 U/mg of protein. No h... |
11350157 | Inclusion Behavior of 4-Nonylphenol into Cyclodextrin Derivatives. | The solubilities of 4-nonylphenol in five kinds of hydroxypropyl-cyclodextrin (HP-CDs) solutions were investigated in order to evaluate them for soil remediation. The relative aqueous-phase concentration of 4-nonylphenol linearly increased with the increasing HP-CD concentration. The addition of HP-beta-CD (degree of s... |
11350137 | The Study of Layer-by-Layer Ultrathin Films by the Dynamic Contact Angle Method. | The self-assembly film fabricated via the layer-by-layer technique was studied by the dynamic contact angle (DCA) method (wilhelmy plate method). The used polyelectrolytes are poly(diallyl-dimethylammonium chloride) (PDDA), poly(etheleneimine) (PEI), diphenylamine-4-diazonium-formaldehyde resin (DR), 2-nitro-N-methyl-4... |
12914049 | Molecular recognition of malto-oligosaccharides by free and metal tetrakis(4-sulfonatophenyl)porphyrins in basic aqueous solutions. | In pH 10.0 buffers, tetrakis(4-sulfonatophenyl)porphyrin (TSPP) has been found to form complexes with malto-oligosaccharides from maltose to maltoheptaose and soluble starch. The peak of the electronic absorption of TSPP is monotonously shifted to longer wavelengths with an increase in the number of D-glucopyranose res... |
11876932 | [The effect of Lipopolysacharide (LPS) on morphology and function of human umbilical endothelial cells (HUVECs)]. | <h4>Objective</h4>To study the effects of LPS on the morphology and function of HUVECs, so as to explore the roles of activated vascular endothelial cells (VEC) by LPS in systemic inflammatory reaction, sepsis and MOF.<h4>Methods</h4>HUVECs primarily cultured in vitro were employed as the model. Inverted microscope was... |
11707948 | Migration behavior of alkylphenols, bisphenol A and bisphenol S studied by capillary electrophoresis using sulfated beta-cyclodextrin. | An application of capillary electrophoresis (CE) using sulfated beta-cyclodextrin (SCD) has been investigated for separating alkylphenols with different chain lengths, as well as bisphenol A and bisphenol S. In the absence of SCD in running buffer, all the phenols migrated at the same velocity as the electroosmotic flo... |
11699729 | Effect of low-density lipoprotein buoyant density and cholesterol content on the formation of lipoprotein(a) particles. | Lipoprotein(a) [Lp(a)] is a unique lipoprotein which resembles low-density lipoprotein (LDL) both in lipid composition and the presence of apolipoprotein B-100 (apo B-100). Lp(a) is, however, distinguishable from LDL by the presence of an additional glycoprotein apolipoprotein(a) [apo(a)], which is covalently attached ... |
11525315 | Traumatic arteriogenic erectile dysfunction: a rat model. | We developed a rat model of traumatic arteriogenic erectile dysfunction (ED) for the study of vasculogenic ED. Bilateral ligation of the internal iliac artery was performed on 30 three-month old male Sprague-Dawley rats as an experimental group. The control group consisted of 12 rats which underwent dissection of the i... |
11516515 | Evaluation of polyplexes as gene transfer agents. | Non-viral transfection systems based on the complexes of DNA and polycations ('polyplexes') were evaluated with respect to their effectiveness, toxicity and cell type dependence in a variety of in vitro models. The panel of polycations examined included branched and linear polyethyleneimines, poly[N-ethyl-4-vinyl pyrid... |
11389144 | Lipid rafts exist as stable cholesterol-independent microdomains in the brush border membrane of enterocytes. | Glycosphingolipid/cholesterol-rich membranes ("rafts")can be isolated from many types of cells, but their existence as stable microdomains in the cell membrane has been elusive. Addressing this problem, we studied the distribution of galectin-4, a raft marker, and lactase, a protein excluded from rafts, on microvillar ... |
11498779 | Tetraspanins and intercellular interactions. | The superfamily of tetraspanins comprises a group of polypeptides with four transmembrane domains that form large supramolecular structures in the plasma membrane through their associations to multiple integral membrane proteins. They are involved in homo- and heterotypic intercellular interactions in different process... |
11506772 | Multiple organ failure in septic patients. | Multiple organ failure (MOF) is the main cause of death in ICUs, especially affecting septic patients. It is strongly related to number of systems with failure, type of system involved, risk factors such as age, previous chronic diseases, delayed or inadequate resuscitation, persistent infection, immune suppression, an... |
11503266 | [Adhesion molecules and their role in organ response after trauma]. | In this paper, we presented general characterization of adhesion molecules and their role in organ response after injury. Severe trauma is frequently complicated by multiple organ dysfunction (MODS) or failure (MOF). The pathogenesis of these syndromes involves a complex interaction of humoral and cellular events. The ... |
11497238 | RecQ helicases and topoisomerases: components of a conserved complex for the regulation of genetic recombination. | Maintenance of genomic stability relies on the efficient and accurate execution of DNA repair pathways, and is essential for cell viability and the prevention of cancer. Mutation of genes encoding RecQ helicases or topoisomerases gives rise to genomic instability through excessive recombination. Here, we review the rec... |
11495056 | New cyclodextrin derivatives as chiral selectors in capillary electrophoresis. | The separation of three pairs of enantiomeric herbicides has been successfully achieved by capillary electrophoresis at two different pH values in the presence of cyclodextrin derivatives previously synthesized in our laboratory. Two of these derivatives constitute a new class of receptor, the hemispherodextrins, in wh... |
11493671 | Nuclear translocation of ferritin in corneal epithelial cells. | Our previous studies have shown that ferritin within developing avian corneal epithelial cells is predominantly a nuclear protein and that one function of the molecule in this location is to protect DNA from UV damage. To elucidate the mechanism for this tissue-specific nuclear translocation, cultured corneal epithelia... |
11484352 | Improving bioavailability and anthelmintic activity of albendazole by preparing albendazole-cyclodextrin complexes. | The bioavailability and anthelmintic activity of albendazole-cyclodextrin complexes (ABZ-CDC) compared to albendazole suspensions in carboxymethylcellulose (ABZ-CMC) was assessed in a mouse model for Trichinella infections. Swiss CD-1 mice experimentally infected with T. spiralis were treated with both formulations aga... |
11482157 | [Occurrence of yeast infections at a surgical intensive care unit]. | The authors evaluate the occurrence of candida infections in the surgical intensive care unit (ICU) in a one-year period. From the group of 1798 patients hospitalized in a surgical ICU there are 50 patients (2.8%) with candida colonisation and even 56 patients (3.1%) with candida infection. The authors evaluate risk fa... |
11474796 | Enantioseparation of flobufen with cyclodextrins studied by capillary electrophoresis and NMR. | <h4>Purpose</h4>The aim of this study was to obtain the resolution of flobufen enantiomers, an antiinflammatory active substance, by capillary electrophoresis with cyclodextrins. The mechanism of complexation and determination of the stoichiometry of the complexes were studied by NMR and the analytical method was devel... |
11471499 | [Hemophagocytosis during multiple organ failure: M-CSF overproduction or viral reactivation?]. | <h4>Objective</h4>This study was aimed to assess the potential role of M-CSF and viral reactivation in the genesis of haemophagocytosis during the multiple organ failure (MOF) syndrome.<h4>Methods</h4>Twenty-five patients (mean age: 60 +/- 16 years; Apache II: 23 +/- 5) sustaining MOF with an unexplained thrombocytopen... |
11470238 | Progesterone inhibits apolipoprotein-mediated cellular lipid release: a putative mechanism for the decrease of high-density lipoprotein. | In order to investigate the mechanism for female gonadal hormones to regulate the plasma high-density lipoprotein (HDL) level, the effect of 17 beta-estradiol and progestogens was examined in vitro on the assembly of HDL by free apolipoprotein A-I (apoA-I) with cellular cholesterol and phospholipid. ApoA-I generated HD... |
11469095 | [Scoring multiple organ failure after severe trauma. Comparison of the Goris, Marshall and Moore scores]. | <h4>Introduction</h4>MOF scores are used to predict, describe and define organ failure. The aim of this study was to compare MOF scoring systems regarding their precision.<h4>Methods</h4>Data on the ICU course of 301 severely injured patients (PTS > 20, age > 16 years) were documented daily for calculation of three MOF... |
11465502 | Modeling and optimization of the chiral selectivity of basic analytes in chiral capillary electrophoresis with negatively charged cyclodextrins using electrochemical detection. | A mathematical model concerning the separation selectivity of basic analytes in chiral capillary electrophoresis (CE) modified with negatively charged cyclodextrins (CDs) has been presented to describe the dependence of chiral selectivity on the buffer pH and the chiral selector concentration. The electrophoretic metho... |
11465494 | Influence of neutral cyclodextrin concentration on plate numbers in capillary electrophoresis. | A quantitative theory of plate number N in capillary electrophoresis was developed for buffers containing neutral cyclodextrins (CDs) capable of forming inclusion complexes. In the theory, N was modeled by longitudinal diffusion, injection extent, width of the detection window, and the detector time constant. The appar... |
11465460 | Self-assembly and dynamics of [2]- and [3]rotaxanes with a dinuclear macrocycle containing reversible Os-N coordinate bonds. | With a dinuclear macrocycle 2 that contains weak reversible OsVI-N coordinate bonds, self-assembly and equilibrium dynamics of [2]- and [3]rotaxanes have been investigated. When the macrocycle 2 was mixed together with threads 4a-e, which all contain an adipamide station but different sizes of end groups, [2]pseudorota... |
11465455 | Ring-opening polymerisation of silver-diphosphine [M2L3] coordination cages to give [M2L3]infinity coordination polymers. | [M2L3] coordination cages and linear [M2L3]infinity polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures d... |
11465450 | A mixed fullerene-ferrocene thermotropic liquid crystal: synthesis, liquid-crystalline properties, supramolecular organization and photoinduced electron transfer. | Grafting of a ferrocene-containing liquid-crystalline malonate derivative to C60 led to the mixed fullerene-ferrocene material 1 which gave rise to a smectic A phase. Cholesterol was used as liquid-crystalline promoter. X-ray diffraction experiments and volumetric measurements indicated that 1 is organized in double la... |
11465447 | Self-assembly of frameworks with specific topologies: construction and anion exchange properties of M3L2 architectures by tripodal ligands and silver(I) salts. | Three five-component architectures, compounds 3, 4, and 5 were obtained by self-assembly of tripodal 1,3,5-tris(imidazol-1-ylmethyl )-2,4,6-trimethylbenzene (6) and 1,3,5-tris(benzimidazol-2-ylmethyl)benzene (7) ligands with silver(I) salts. The structures of these novel complexes have been determined by X-ray crystall... |
11465444 | Cooperative multipoint recognition of organic dyes by bis(beta-cyclodextrin)s with 2,2'-bipyridine-4,4'-dicarboxy tethers. | A series of novel 6,6'-bis(beta-cyclodextrin)s linked by 2,2'-bipyridine-4,4'-dicarboxy tethers; that is, 2,2'-bipyridine-4,4'-dicarboxy-bridged bis(6-O-beta-cyclodextrin) (2) and N,N'-bis(2-aminoethyl )-2,2'-bipyridine-4,4'-dicarboxamide-bridged (3), N,N'-bis(5-amino-3-azapentyl)-2,2'-bipyridine-4,4'-dicarboxamide-bri... |
11465442 | Halogen bonding: a paradigm in supramolecular chemistry. | The term halogen bonding describes the tendency of halogen atoms to interact with lone pair possessing atoms. The binding features and structural properties of halogen bonding are discussed and applied to drive the intermolecular self-assembly of hydrocarbons and perfluorocarbons in chemo-, site-, and enantioselective ... |
11462805 | The A3 adenosine receptor induces cytoskeleton rearrangement in human astrocytoma cells via a specific action on Rho proteins. | In previous studies, we have demonstrated that exposure of astroglial cells to A3 adenosine receptor agonists results in dual actions on cell survival, with "trophic" and antiapoptotic effects at nanomolar concentrations and induction of cell death at micromolar agonist concentrations. The protective actions of A3 agon... |
11459314 | High-performance liquid chromatographic enantioseparation of bicyclic 1,3-amino alcohols. | Different high-performance liquid chromatographic methods were developed for the separation and identification of enantiomers of diendo- and diexo-3-aminobicyclo[2.2.1]heptane-2-methanol and diendo- and diexo-3-amino-bicyclo[2.2.1]hept-5-ene-2-methanol derivatives. Direct separation was carried out on a naphthylethyl c... |
11457386 | Co-conformational variability of cyclodextrin complexes studied by induced circular dichroism of azoalkanes. | The solution structures of the beta-cyclodextrin complexes between 2,3-diazabicyclo[2.2.2]oct-2-ene (1) and its 1-isopropyl-4-methyl derivative 2 have been investigated by means of induced circular dichroism (ICD) and MM3-92 force-field calculations, which considered the effect of solvation within a continuum approxima... |
11457385 | Self-assembly of beta-sheets into nanostructures by poly(alanine) segments incorporated in multiblock copolymers inspired by spider silk. | Selective replacement of the amorphous peptide domain of a spider silk with poly(ethylene glycol) gave N. clavipes silk-inspired polymers having similar solid-state structures and very good mechanical properties. The tendency of poly(alanine) having appropriate chain length to form beta-sheets and the facility with whi... |
11457383 | Chiral softballs: synthesis and molecular recognition properties. | Studies on the different congeners of the softball were undertaken to explore structural variants for enantioselective encapsulation. Two different spacer elements in the monomeric subunit render the dimeric softball chiral although the monomer itself is achiral. The dimers represent capsules with dissymmetric cavities... |
11452988 | Simultaneous separation of common mono- and divalent cations on a zirconium-modified silica gel column by ion chromatography with non-suppressed conductimetric detection and tartaric acid-15-crown-5 as eluent. | The application of laboratory-made zirconium-modified silica gels (Zr-silicas) as cation-exchange stationary phases to ion chromatography with conductimetric detection (IC-CD) for common mono- and divalent cations (Li+, Na+, NH4+, K+, Mg2+ and Ca2+) was carried out. Zr-silicas were prepared by the reaction of the silan... |
11448527 | Origins of life: a route to nanotechnology. | The origins of life and nanotechnology are two seemingly disparate areas of scientific investigation. However, the fundamental questions of life's beginnings and the applied construction of a Drexlerian nanotechnology both share a similar problem; how did and how can self-reproducing molecular machines originate? Here ... |
11445963 | A direct sensitized fluorimetric determination of 5,10,15,20-tetra(m-hydroxyphenyl)chlorin [m-THPC (Foscan)] in human plasma using a cyclodextrin inclusion complex. | The 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) (Foscan) is a photosensitizer used in the photodynamic therapy (PDT) of cancers which is currently under clinical trial. The formation of a m-THPC inclusion complex with dimethyl-beta-cyclodextrin (Me-beta-CD) in solution was demonstrated on the basis of circular di... |
11445962 | Determination of naproxen in pharmaceutical preparations by room-temperature phosphorescence. A comparative study of several organized media. | Different methods for the determination of naproxen by room-temperature phosphorescence (RTP) using organized media such as cyclodextrins (beta-CD and gamma-CD) and micelles (Triton X-100 and sodium dodecyl sulfate) are reported. The inclusion complexes formed between both beta- and gamma-cyclodextrins and naproxen wer... |
11445942 | Chemiluminescent flow-through sensor for 1,10-phenanthroline based on the combination of molecular imprinting and chemiluminescence. | A functional polymer for the catalysis of the chemiluminescent reaction and molecular recognition ability of 1,10-phenanthroline was prepared based on the molecular imprinting method. The structural and catalytic roles of transition metal ion interactions were applied in the material design. A ternary complex, 4-vinylp... |
11445940 | Molecularly imprinted polymer sensors for pesticide and insecticide detection in water. | Antibodies, peptides, and enzymes are often used as molecular recognition elements in chemical and biological sensors. However, their lack of stability and signal transduction mechanisms limits their use as sensing devices. Recent advances in the field of molecularly imprinted polymers (MIPs) have created synthetic mat... |
11445939 | Systematic study of steric and spatial contributions to molecular recognition by non-covalent imprinted polymers. | Although molecular imprinting is a widely accepted method for producing template specific polymers, the general rules for prediction and control of the binding and catalytic properties of these materials are still not fully understood. One reason for this is the problematic structural analysis of the active sites in th... |
11445937 | Effect of solvent composition on chiral recognition ability of molecularly imprinted DIDE derivatives. | In the present study, molecularly imprinted materials from the tetrapeptide derivative, H-Asp(OcHex)-Ile-Asp(OcHex)-Glu(OBzl)-CH2-, were adopted as samples to study the effect of the polarity of the environment on the chiral (molecular) recognition ability. The optimum composition, with the best chiral recognition, is ... |
11446647 | Multipeptide-metalloporphyrin assembly on a dendrimer template and photoinduced electron transfer based on the dendrimer structure. | To construct an artificial photosynthetic system, peptide dendrimers [n-(X-HLY)PAMAMs: X = R, E; Y= L, F; n=4, 8, 16, 32 and 64 segments], in which amphiphilic alpha-helix peptides (X-HLY: R-HLL, E-HLL and R-HLF) were introduced at the end groups of polyamidoamine dendrimers (PAMAMs), were designed and synthesized. The... |
11446645 | Metallocyclic receptors with Re(I)/Os(II)-based moieties: molecular photophysics and selective molecular sensing. | New metallocyclic Re(I) and Os(II) complexes with polyphosphane/polyyne spacers, including dimers [(Re(CO)3Cl(C2nP2))2] (n = 1, 1; 2, 2) and tetramers [(Re(CO)3Cl(C2nP2))4] (n = 1, 3; 2, 4, C2P2 = Ph2P-C...C-PPh2, C4P2 = Ph2P-C...C-C...C-PPh2), as well as the mixed-metal [(Re(CO)3Cl)2(Os(bpy)2)2(C2P2)4](PF6)4 (6, bpy =... |
11446644 | Supramolecular organometallic polymer chemistry: multiple morphologies and superstructures from the solution self-assembly of polyferrocene-block-polysiloxane-block-polyferrocene triblock copolymers. | The solution self-assembly of an organometallic-inorganic triblock copolymer, poly(ferrocenyldimethylsilane)-block-poly(dimethylsiloxane)-block-poly-(ferrocenyldimethylsilane) (PFDMS-b-PDMS-b-PFDMS, 3b; block ratio 1:13:1; Mn = 2.88 x 10(4) gmol(-1), polydispersity (PDI) 1.43 (gel permeation chromatography, GPC)) was s... |
11446643 | Expanded phthalocyanine analogues: synthesis and characterization of new triazole-derived annulenes containing six heterocyclic subunits. | A series of heteroannulenes 3a-f containing four subunits of isoindole, two 1,2,4-triazole moieties, and six aza bridges have been synthesized by dimerization of the corresponding metallated, three-unit intermediates 5a-f. All these 28 pi-electron triazolephthalocyanine derivatives coordinate two metal ions within thei... |
11442038 | Retention behaviour and fluorimetric detection of procaine hydrochloride using carboxymethyl-beta-cyclodextrin as an additive in reversed-phase liquid chromatography. | The retention behaviour of procaine hydrochloride on an Alltima octadecyl silica (C18) column, with a mobile phase containing negatively charged carboxymethyl-beta-cyclodextrin (CM-beta-CD), influenced by a combination of hydrophobic and electrostatic interactions was systematically investigated. Various factors affect... |
11438971 | Quantification of D/L-aspartic acids in Aplysia californica central nervous system by beta-cyclodextrin modified micellar electrokinetic chromatography. | In presence of an organic modifier (e.g. methanol), separation of amino acid enantiomers tagged with naphthalene-2,3-dicarboxaldehyde by beta-cyclodextrin modified micellar electrokinetic chromatography was dramatically improved. Coupled with laser-induced fluorescence detection, the method was well suited for analysis... |
11438966 | Separation of naturally occurring triterpenoidal saponins by capillary zone electrophoresis. | A high-performance capillary electrophoresis (HPCE) was successfully applied to the separation and quantitation of naturally occurring oleanene triterpenoidal saponins. The HPCE adapted to the separation of two pairs of disteriomeric saponins (1-2) or (3-4), obtained from Trifolium alexandrinum seeds, was based on capi... |
11432954 | An improved Na+-selective microelectrode for intracellular measurements in plant cells. | The high background K+ concentration in plant cells is a problem for intracellular measurements of Na+ using ion-selective microelectrodes. The discrimination between Na+ and K+ of the microelectrode ionophore molecule limits the usefulness of this technique. A new Na+-selective microelectrode with an ionophore incorpo... |
11428666 | A tryptamine analog with high affinity to the heart tissues is a potential antiarrhythmic agent. | A novel tryptamine analog, 1-methyl-3-[N-(3-indolyl)ethyl]carbamoyl-1,4-dihydropyridine (T-CDS) was synthesized and converted into a stable, solid complex with 2-hydroxypropyl-beta-cyclodextrin. An aqueous solution of the complex was given intravenously to dogs and the concentration of T-CDS and its corresponding quate... |
11421786 | Convergent synthesis of noncovalent metallodendrimers containing hydrophobic dendrons at the periphery. | The noncovalent synthesis of "layer-block" metallodendrimers containing hydrophobic shells of covalent dendritic wedges at the periphery is described. Starting from first- and second-generation Fréchet wedges having phosphines at their focal point, convergent dendritic growth yields third- and fourth-generation metallo... |
11421780 | Studies on porphyrin-quinhydrone complexes: molecular recognition of quinone and hydroquinone in solution. | Free-base and zinc(II) porphyrins bearing either one, two, or four hydroquinone entities at the meso positions are shown to bind quinones in solutions via a quinhydrone pairing mechanism. Electrochemical studies reveal that the quinhydrone complexes are stabilized by charge-transfer interactions between the donor (hydr... |
11421779 | General approach to the synthesis of persubstituted hydrophilic and amphiphilic beta-cyclodextrin derivatives. | Heptakis(2,3,6-tri-O-allyl)-beta-cyclodextrin 2 was converted to heptakis[2,3,6-tri-O-(2,3-dihydroxypropyl)]-beta-cyclodextrin 3 by osmium tetroxide-catalyzed dihydroxylation. A diastereomeric mixture of 3 was treated with sodium periodate followed by sodium borohydride to give heptakis[2,3,6-tri-O-(2-hydroxyethyl)]-be... |
11421777 | Conformational analysis of dehydrodidemnin B (aplidine) by NMR spectroscopy and molecular mechanics/dynamics calculations. | Dehydrodidemnin B (DDB or aplidine), a potent antitumoral natural product currently in phase II clinical trials, exists as an approximately 1:1 mixture of two slowly interconverting conformations. These are sufficiently long-lived so as to allow their resolution by HPLC. NMR spectroscopy shows that this phenomenon is a... |
11422598 | Itraconazole oral solution and intravenous formulations: a review of pharmacokinetics and pharmacodynamics. | Itraconazole is a triazole antifungal agent with a broad spectrum of activity. It is well tolerated and highly efficacious, particularly because its main metabolite, hydroxy-itraconazole, also has considerable antifungal activity. Two new formulations of itraconazole, an oral solution and an intravenous formulation, ha... |
11422463 | Cell lysis is responsible for the appearance of extracellular urease in Helicobacter pylori. | <h4>Background</h4>Helicobacter pylori is a neutralophilic bacterium that colonizes the acidic human gastric surface using the neutralizing capacity of a constitutively produced urease. Urease is present both in the cytoplasm and bound to the outside surface of the bacteria. The origin of the surface urease continues t... |
11421510 | Cyclodextrin as a potential drug carrier in salbutamol dry powder aerosols: the in-vitro deposition and toxicity studies of the complexes. | This research was carried out to develop a new carrier in dry powder aerosols. Two types of cyclodextrin were chosen; gamma cyclodextrin (GCD) and dimethyl-beta-cyclodextrin (DMCD) as carriers in dry powder formulations. Salbutamol was used as a model drug and a control formulation containing lactose and the drug was i... |
11418049 | Studies on the total synthesis of RP 66453: synthesis of fully functionalized 15-membered biaryl-containing macrocycle. | [structure: see text] Palladium-catalyzed Suzuki cross-coupling, Corey's enantioselective alkylation of glycine template, and macrolactamization are key steps in an efficient synthesis of the 15-membered macrocycle 2. |
11373402 | Influence of hydrogen bonding on the second harmonic generation effect: neutron diffraction study of 4-nitro-4'-methylbenzylidene aniline. | A neutron diffraction study of the non-linear optical (NLO) material 4-nitro-4'-methylbenzylidene aniline (NMBA) is presented. NMBA exhibits a large macroscopic second-order NLO susceptibility, chi((2)), and this study shows that hydrogen bonding is, in part, responsible for this. No hydrogen bonding was reported in th... |
11373401 | Non-covalent interactions in the crystallization of the enantiomers of 1,7-dioxaspiro. | The enantiomers of racemic olive fly sex pheromone 1,7-dioxaspiro[5.5]undecane (1) have been isolated by crystallization with enantiospecific cyclodextrin hosts: (S)-(1) crystallizes with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) and (R)-(1) with hexakis(2,3,6-tri-O-methyl)-alpha-cyclodextrin (TMalphaCD... |
11373392 | X-ray and neutron structure of 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol (P326); some pitfalls of automatic data collection. | The structure of the crown ether 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol, C(24)H(30)O(6).H(2)O (1), code name P326, the parent compound for a series of derivatives, has been determined by both X-ray diffraction at room temperature and neutron diffraction at very low temperat... |
11373391 | Hydrated salts of 3,5-dihydroxybenzoic acid with organic diamines: hydrogen-bonded supramolecular structures in two and three dimensions. | The trigonally trisubstituted acid 3,5-dihydroxybenzoic acid forms hydrated salt-type adducts with organic diamines. In 1,4-diazabicyclo[2.2.2]octane-3,5-dihydroxybenzoic acid-water (1/1/1) (1), where Z' = 2 in P2(1)/c, the constitution is [HN(CH(2)CH(2))(3)N](+).[(HO)(2)C(6)H(3)COO](-).H(2)O: the anions and the water ... |
11373390 | Hydrated metal complexes of N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)glycinate: interplay of molecular, molecular-electronic and supramolecular structures. | The title anion, (C(7)H(8)N(5)O(4))(-), L(-), forms hydrated metal complexes with a range of metal ions M(+) and M(2+). Lithium and manganese(II) form finite molecular aggregates [Li(L)(H(2)O)(3)] (1) and [Mn(L)(2)(H(2)O)(4)].6H(2)O (4) in which the molecular aggregates are linked into three-dimensional frameworks by e... |
11373388 | Hydrogen-bonded hexagonal and pseudo-hexagonal grid motifs in supramolecular cobalt(II) and nickel(II) cupferronato complexes incorporating neutral N-donors with intermolecular NH2 connectors and solvent molecules. | The cobalt(II) and nickel(II) cupferronato (N-nitroso-N-phenylhydroxylaminato) mixed-ligand complexes of 2-aminopyridine (2-NH(2)py) [Co(PhN(2)O(2))(2)(2-NH(2)py)(2)] (1), [Ni(PhN(2)O(2))(2)(2-NH(2)py)(2)] (2) and 2,6-diamino-4-phenyl-1,3,5-triazine (dpt) [Co(PhN(2)O(2))(2)(dpt)(2)].[Co(PhN(2)O(2))(2)(EtOH)(2)] (3) hav... |
11414836 | Phenylthiyl radical complexes of gallium(III), iron(III), and cobalt(III) and comparison with their phenoxyl analogues. | Three hexadentate, asymmetric pendent arm macrocycles containing a 1,4,7-triazacyclononane-1,4-diacetate backbone and a third, N-bound phenolate or thiophenolate arm have been synthesized. In [L(1)](3)(-) the third arm is 3,5-di-tert-butyl-2-hydroxybenzyl, in [L(2)](3)(-) it is 2-mercaptobenzyl, and in [L(3)](3)(-) it ... |
11414832 | Stiff, and sticky in the right places: the dramatic influence of preorganizing guest binding sites on the hydrogen bond-directed assembly of rotaxanes. | Structural rigidity and the preorganization of thread binding sites are shown to have a major influence on template efficiency in the synthesis of hydrogen bond-assembled rotaxanes. Preorganization is so effective, in fact, that with good hydrogen bond acceptors (amides) a "world record" yield of 97% for a [2]rotaxane ... |
11414831 | Chiral recognition by CD-sensitive dimeric zinc porphyrin host. 2. Structural studies of host-guest complexes with chiral alcohol and monoamine conjugates. | A structural study of complexes formed between a dimeric zinc porphyrin tweezer (host) and chiral monoalcohols and monoamines derivatized by a bidentate carrier molecule (guest) confirmed that their CD couplets arise from the preferred porphyrin helicity of 1:1 host-guest complexes. NMR experiments and molecular modeli... |
11414830 | Chiral recognition by CD-sensitive dimeric zinc porphyrin host. 1. Chiroptical protocol for absolute configurational assignments of monoalcohols and primary monoamines. | A general microscale protocol for the determination of absolute configurations of primary amino groups or secondary hydroxyl groups linked to a single stereogenic center is described. The chiral substrates are linked to the achiral trifunctional bidentate carrier molecule (3-aminopropylamino)acetic acid (1, H(2)NCH(2)C... |
11414829 | Reactivity at the interface of chiral amphiphilic dendrimers. High asymmetric reduction by NaBH(4) of various prochiral ketones. | New amphiphilic dendrimers derived from PAMAM and D-gluconolactone were found to induce chirality in the reduction of prochiral ketones by NaBH(4), in heterogeneous (THF) and homogeneous (water) conditions. The third generation of these amphiphilic dendrimers, G(3)G, was found to be a good chiral ligand for the reducti... |
11414828 | Internucleobase-interaction-directed self-assembly of nanofibers from homo- and heteroditopic 1,omega-nucleobase bolaamphiphiles. | The complementary 1,omega-thymine, 1,omega-adenine, and 1,omega-(thymine, adenine) bolaamphiphiles, [N,N'-bis[3-(2,4-dihydroxy-5-methylpyrimidine-1-yl)propionyl]1,n-diaminoalkane [T-n-T (n = 10, 11, 12)], N, N'-bis[3-(6-aminopurine-9-yl)propionyl]1,n-diaminoalkane [A-n-A (n = 10, 11, 12)], and N-[3-(2,4-dihydroxy-5-met... |
11414825 | Total synthesis of (-)-cylindrocyclophanes A and F exploiting the reversible nature of the olefin cross metathesis reaction. | Efficient total syntheses of the C(2)-symmetric (-)-cylindrocyclophanes A and F (1a and 1f) have been achieved. The initial strategy featured the use of a common advanced intermediate to assemble in stepwise fashion the required macrocycle of 1f, exploiting in turn a Myers reductive coupling followed by ring-closing me... |
11414823 | Fast and convenient divergent synthesis of aliphatic ester dendrimers by anhydride coupling. | A novel divergent approach was developed for the synthesis of dendritic aliphatic polyester structures using an acetal-protected anhydride derivative of 2,2-bis(hydroxymethyl)propionic acid as the acylating agent. This divergent synthesis is remarkable, because unlike all others, it only requires a small excess of reag... |
11412086 | Positive allosteric systems designed on dynamic supramolecular scaffolds: toward switching and amplification of guest affinity and selectivity. | Positive homotropic allosterism appears in important information transduction processes where chemical and physical signals are efficiently amplified. The phenomena are ubiquitous in nature, but the general methodology for the design of such allosteric systems is not yet established in an artificial system. This accoun... |
11412084 | Shuttles and muscles: linear molecular machines based on transition metals. | Transition-metal-containing rotaxanes can behave as linear motors at the molecular level. The molecules are set into motion either by an electrochemical reaction or using a chemical signal. In a first example, a simple rotaxane is described that consists of a ring threaded by a two-coordination-site axle. The ring cont... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.