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15551321 | Molecular recognition and crystal energy landscapes: an X-ray and computational study of caffeine and other methylxanthines. | We introduce a new approach to crystal-packing analysis, based on the study of mutual recognition modes of entire molecules or of molecular moieties, rather than a search for selected atom-atom contacts, and on the study of crystal energy landscapes over many computer-generated polymorphs, rather than a quest for the o... |
15551319 | Hierarchical self-assembly of supramolecular spintronic modules into 1D- and 2D-architectures with emergence of magnetic properties. | Hierarchical self-assembly of complex supramolecular architectures allows for the emergence of novel properties at each level of complexity. The reaction of the ligand components A and B with Fe(II) cations generates the [2x2] grid-type functional building modules 1 and 2, presenting spin-transition properties and preo... |
15551310 | Water-soluble molecular capsules: self-assembly and binding properties. | The self-assembly and characterization of water-soluble calix[4]arene-based molecular capsules (12) is reported. The assemblies are the result of ionic interactions between negatively charged calix[4]arenes 1 a and 1 b, functionalized at the upper rim with amino acid moieties, and a positively charged tetraamidiniumcal... |
15549767 | Dynamic equilibrium between a supramolecular capsule and bowl generated by inter- and intramolecular metal clipping. | The metal-induced self-assembly of a resorcin[4]arene derivative 1 that has four pyridine units as pendent groups and two equivalents of [M(dppp)(OTf)(2)] (M=Pd, Pt) results in a dynamic equilibrium between an interclipped supramolecular capsule 3 and an intraclipped bowl 4 in nitromethane, although the interclipped ca... |
15540258 | Using diffusion NMR to characterize guanosine self-association: insights into structure and mechanism. | This paper presents results from a series of pulsed field gradient (PFG) NMR studies on lipophilic guanosine nucleosides that undergo cation-templated assembly in organic solvents. The use of PFG-NMR to measure diffusion coefficients for the different aggregates allowed us to observe the influences of cation, solvent a... |
15540257 | Synthesis, characterization, and properties of subporphyrazines: a new class of nonplanar, aromatic macrocycles with absorption in the green region. | Novel subphthalocyanine analogues that display strong absorption in the green region have been synthesized by using a boron template cyclotrimerization of maleonitrile derivatives. The spectroscopic properties of these macrocycles indicate that, like subphthalocyanines, they have 14 pi electrons and are aromatic compou... |
15484182 | A new class of non-racemic chiral macrocycles: a conformational and synthetic study. | Amino alcohols have been used to introduce non-racemic chirality into macrocycles using a modular approach that relies on a Heck macrocyclisation reaction. A wide variety of macrocycles have been synthesised, and their structures studied using X-ray crystallography and molecular modelling. A fragmentation reaction enco... |
15586392 | Inclusion complex formation between alpha-cyclodextrin and biodegradable aliphatic polyesters. | Inclusion complexes (ICs) between alpha-cyclodextrin (alpha-CD) and three kinds of biodegradable aliphatic polyesters with different sequence lengths of the monomeric repeating units poly(3-hydroxypropionate) [P(3HP)], poly(4-hydroxybutyrate) [P(4HB)] and poly(epsilon-caprolactone)(PCL) were prepared by mixing a soluti... |
15586386 | A novel approach to biodegradable block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by new aluminum metal complexes. | The chemical preparation of structurally well-defined biodegradable amphiphilic block copolymers is now of great interest for biomedical applications and the fundamental mimetic study of biomacromolecule self-assembly. For this purpose, in this study, (R,R)-N,N'-bis(3-tert-butylsalicylidene)-1,2-cyclohexanediamine 2 as... |
15586385 | Formation and characterization of inclusion complexes of poly(butylene succinate) with alpha- and gamma-cyclodextrins. | The inclusion complexes (ICs) of alpha- and gamma-cyclodextrins (CDs) with high-molecular-weight poly(butylene succinate) (PBS) were prepared and characterized by differential scanning calorimetry, Fourier-transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction, solid-state 13C nuclear magnetic resonance ... |
15634169 | Viscoelastic properties of dendrimers in the melt from nonequlibrium molecular dynamics. | The viscoelastic properties of dendrimers of generation 1-4 are studied using nonequilibrium molecular dynamics. Flow properties of dendrimer melts under shear are compared to systems composed of linear chain polymers of the same molecular weight, and the influence of molecular architecture is discussed. Rheological ma... |
15634161 | Conformation selective assembly of carboxyphenyl substituted porphyrins on Au (111). | The selective assembly of carboxyphenyl substituted porphyrins on the Au (111) surface has been studied using scanning tunneling microscopy. We find that conformational isomers of the porphyrins are induced upon adsorption and are selectively assembled into hydrogen-bonded supramolecular clusters or wires on the surfac... |
15634156 | Coarse-grained simulations of lipid bilayers. | A minimal model of lipid molecules consisting of bead-spring representation is developed. The basic interactions are hydrophobic and polar interactions. Essential physical features of lipid bilayers are maintained using this model, and relatively long times can be simulated in comparison to atomistic models. Self-assem... |
15634057 | Three-photon absorption in anthracene-porphyrin-anthracene triads: a quantum-chemical study. | We have applied correlated quantum-chemical methods to investigate the three-photon absorption (3PA) response of a porphyrin triad derivative, where the central macrocycle is linked in mesopositions to two anthracene units via acetylenic bridges. The 3PA frequency-dependent spectrum of this derivative is dominated by a... |
15582614 | Isolation and characterization of two positional isomers of novel heterogeneous branched cyclomaltohexaoses (alpha-cyclodextrins) having a D-galactobiosyl residue on the side chain. | Transgalactosylated products, 2-O-alpha-D-galactobiosyl-cyclomaltohexaoses (alpha-cyclodextrins, alphaCDs), were synthesized by alpha-galactosidase from coffee bean using melibiose and alphaCD as a donor substrate and an acceptor, respectively. Two positional isomers of 2-O-alpha-galactobiosyl-alphaCDs were isolated an... |
15636515 | Conformational effect of silica-supported poly(octadecyl acrylate) on molecular-shape selectivity of polycyclic aromatic hydrocarbons in RP-HPLC. | Poly(octadecyl acrylate) with a terminal reactive group was synthesized by radical telomerization in various solvents. The polymers were grafted onto porous silica for use in RP-HPLC, and the molecular recognition ability was investigated along with the selectivity for the structural isomers of polycyclic aromatic hydr... |
15636508 | Electrochemical and luminescent properties of new mononuclear ruthenium(II) and binuclear iridium(III)-ruthenium(II) terpyridine complexes. | Hexafluorophosphate salts of mononuclear complexes [Ru(II)Cl(L)(terpy)]+ (L = dmbpy (1); dpbpy (2), sambpy (3), and dpp (7), and binuclear complexes [Ru(II)2Cl2(dpp)(terpy)2]2+ (8) and [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+ (9) were prepared and characterized. Abbreviations of the ligands are bpy = 2,2'-bipyridine, dmbpy = ... |
15609940 | Design, synthesis, and photochemical behavior of poly(benzyl ester) dendrimers with azobenzene groups throughout their architecture. | A new class of dendrons and dendrimers containing azobenzene units (bearing up to 29 azobenzene groups for four generations) were designed and synthesized with the convergent method, which uses azobenzene derivatives as monomers and benzyl ester groups as linkages leading to photoresponsive dendrons and dendrimers with... |
15609937 | Assembly and characterization of novel hydrogen-bond-induced nanoscale rods. | A class of bis-urea compounds with perylene bisimide was synthesized and characterized successfully. (1)H NMR and fluorescence spectra confirmed that strong hydrogen-bonding interactions between neighboring urea groups were formed. Interestingly, the photocurrent measurement showed that the self-assembled films of bis-... |
15628143 | Enantiomeric separation of naphthalene-2,3-dicarboxaldehyde derivatized DL-3,4-dihydroxyphenylalanine and optical purity analysis of L-3,4-dihydroxyphenylalanine drug by cyclodextrin-modified micellar electrokinetic chromatography. | A new cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) method for the enantiomeric separation of 3,4-dihydroxyphenylalanine (DOPA), derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) to produce cyanobenzoisoindole (CBI) derivative, has been developed. The unsubstituted alpha-, beta-, gamma-cy... |
15628141 | Rapid and sensitive determination of anthraquinones in Chinese herb using 1-butyl-3-methylimidazolium-based ionic liquid with beta-cyclodextrin as modifier in capillary zone electrophoresis. | The present study reported the ionic liquid (IL) used as running electrolyte in capillary zone electrophoresis (CZE) with beta-cyclodextrin (beta-CD) as modifier for the separation of anthraquinones extract of Chinese herb Paedicalyx attopevensis Pierre ex Pitard. The optimum running electrolyte was 60 mM 1-butyl-3-met... |
15628140 | Evaluation of newly synthesized derivative of cyclodextrin for the capillary electrophoretic separation. | A highly water-soluble new cyclodextrin (CD) derivative 2-O-acetonyl-2-O-hydroxypropyl-beta-CD (2-AHP-beta-CD) was synthesized and tested as an effective chiral selector for the capillary zone electrophoretic resolution (Rs) of several basic and acidic analytes. The primary purpose of the research was to explore the ca... |
15628131 | Peralkylated-beta-cyclodextrin used as gas chromatographic stationary phase prepared by sol-gel technology for capillary column. | For the first time, three peralkylated-beta-cyclodextrins (beta-CD), permethylated-beta-CD, perethylated-beta-CD and perpentylated-beta-CD, were coated onto the fused-silica capillary by sol-gel method with simplicity and rapidity. Multiple steps in conventional column preparation technology were avoided. Also, these n... |
15628124 | Enantioseparation on mono(6A-n-allylamino-6A-deoxy)permethylated 3-cyclodextrin covalently bonded silica gel. | A chiral selector, mono(6A-N-allylamino-6A-deoxy)permethylated beta-cyclodextrin, was synthesized through a facile synthetic route and chemically immobilized onto porous silica gel via hydrosilylation to afford a cyclodextrin based chiral stationary phase MeCD-CSP. This chiral stationary phase exhibited good enantiosel... |
15606216 | Assemblies of redox-active metallodendrimers using hydrogen bonding for the electrochemical recognition of the H2PO4- and adenosine-triphosphate (ATP2-) anions. | Two families of five metallodendrimers have been assembled by hydrogen bonding between the primary amino groups of DSM dendrimers G(n)-DAB-dendr-(NH(2))x (n = 1-5; x = 4, 8, 16, 32, 64) and the OH group of phenol dendrons containing a triallyl or a triferrocenylalkyl tripod in para position. These H-bonded dendrimers n... |
15606215 | Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 2. Metal complexes of tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine: linear and nonlinear optical properties and electrochemical behavior. | A series of metal complexes of tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine, [Py(8)TPyzPzH(2)], having the general formula [Py(8)TPyzPzM].xH(2)O (M = Mg(II)(H(2)O), Mn(II), Co(II), Cu(II), Zn(II); x = 3-8) were synthesized by reaction of the free-base macrocycle with the appropriate metal acetate in pyridine or... |
15606214 | Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 1. Tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine: a new macrocycle with remarkable electron-deficient properties. | A new pyrazinoporphyrazine macrocycle carrying externally appended pyridine rings, tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine (hydrated), [Py(8)TPyzPzH(2)].2H(2)O, was prepared in high yield by direct cyclotetramerization of the precursor, 2,3-dicyano-5,6-di(2-pyridyl)-1,4-pyrazine, [(CN)(2)Py(2)Pyz], in the ... |
15606210 | The (Calix[4]arene)chloromolybdate(IV) anion [MoCl(Calix)](-): a convenient entry into molybdenum Calix[4]arene chemistry. | The complex (HNEt(3))[MoCl(NCMe)(Calix)] (1), prepared from the reaction of [MoCl(4)(NCMe)(2)] with p-tert-butylcalix[4]arene, H(4)Calix, in the presence of triethylamine, has been used as a source of the d(2)-[Mo(NCMe)(Calix)] fragment. Complex 1 is readily oxidized with PhICl(2) to afford the molybdenum(VI) dichloro ... |
15606203 | Synthesis and structure of mercurous ion and dinuclear lead(II) complexes of the 28-membered selenaaza macrocycle: dominance of the chelate ring size effect and conformational requirement over soft-soft interactions. | The flexible and larger ring size macrocycle 4 (C(36)H(46)N(6)Se(2)) afforded stable complex 5 [Hg(2)(PF(6))(2)[C(36)H(46)N(6)Se(2)]] on treatment with 1 equiv of mercuric acetate followed by addition of NH(4)PF(6). The reaction of Pb(OCOCH(3))(2).4H(2)O with 4 followed by treatment with NH(4)PF(6) resulted in a dinucl... |
15612744 | Assembly of a supramolecular capsule on a molecular printboard. | A molecular capsule based on ionic interactions between two oppositely charged calix[4]arenes, 1 and 2, was assembled both in solution and on a surface. In solution, the formation of the equimolar assembly 1.2 was studied by (1)H NMR, ESI-MS, and isothermal titration calorimetry, giving an association constant (K(a)) o... |
15612719 | Temperature-dependent behavior of a symmetric long-chain bolaamphiphile with phosphocholine headgroups in water: from hydrogel to nanoparticles. | The temperature-dependent self-assembly of the single-chain bolaamphiphile dotriacontan-1,1'-diyl-bis[2-(trimethylammonio)ethyl phosphate] (PC-C32-PC) was investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray scattering, r... |
15578841 | Synthesis, structure, and complexation of a large 28-mer macrocycle containing two binding sites for either anions or metal ions. | The "one-pot" synthesis and characterization of a large 28-mer macrocycle (H(4)L(2)) with oxamido units capable of complexing guest ions through oxygen or nitrogen donor atoms is reported. Single-crystal structure determination of H(8)L(2)(NO(3))(4) and (Cu(2)[H(2)L(2)](H(2)O)(2))(NO(3))(2) demonstrated that the macroc... |
15578836 | Efficient DNA binding by optically Pure Ruthenium Tris(bipyridyl) complexes incorporating carboxylic functionalities. Solution and structural analysis. | Herein, we report on the binding of optically pure ruthenium complexes Delta- or Lambda-[Ru(bpy)(2)(L-L)][PF(6)](2) [L-L = Hcmbpy = 4-carboxy-4'-methyl-2,2'-bipyridine (1), L-L = H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine (2)] to DNA. The binding constants of the two enantiomeric Delta-1 and Lambda-1 complexes to DNA w... |
15600365 | Crystalline inclusion compounds constructed through self-assembly of isonicotinic acid and thiocyanato coordination bridges. | The synthesis, crystal structures, inclusion ability, and structural robustness of novel crystalline inclusion compounds of [Ni(SCN)2(isoH)2].xG (isoH = isonicotinic acid; G = aromatic guest) are described. The inclusion compounds are constructed by stacking identical 2D host layers that consist of SCN-, isoH, and Ni2+... |
15600363 | Selective 226Ra2+ ionophores provided by self-assembly of guanosine and isoguanosine derivatives. | The self-assembled guanosine (G 1)-based hexadecamers and isoguanosine (isoG 2)-based decamers are excellent 226Ra2+ selective ionophores even in the presence of excess alkali (Na+, K+, Rb+, and Cs+) and alkaline earth (Mg2+, Ca2+, Sr2+, and Ba2+) cations over the pH range 3-11. G 1 requires additional picrate anions t... |
15600353 | An excimer-based, binuclear, on-off switchable calix[4]crown chemosensor. | A new fluorescent chemosensor with two different types of cation binding sites on the lower rims of a 1,3-alternate calix[4]arene (1) is synthesized. Two pyrene moieties linked to a cation recognition unit composed of two amide groups form a strong excimer in solution. For 1, the excimer fluorescence is quenched by Pb2... |
15600349 | Proton-driven self-assembled systems based on cyclam-cored dendrimers and [Ru(bpy)(CN)4]2-. | 1,4,8,11-tetraazacyclotetradecane (cyclam), which is one of the most extensively investigated ligands in coordination chemistry, in its protonated forms, can play the role of host toward cyanide metal complexes. We have investigated the acid-driven adducts formed in acetonitrile-dichloromethane (1:1 v/v) solution by [R... |
15600335 | Design and characterization of programmable DNA nanotubes. | DNA self-assembly provides a programmable bottom-up approach for the synthesis of complex structures from nanoscale components. Although nanotubes are a fundamental form encountered in tile-based DNA self-assembly, the factors governing tube structure remain poorly understood. Here we report and characterize a new type... |
15600312 | Long-range flow-induced alignment of self-assembled rosette nanotubes on Si/SiOx and poly(methyl methacrylate)-coated Si/SiOx. | Helical rosette nanotubes are obtained through the self-assembly of low molecular weight synthetic modules in water. Here we demonstrate that despite their dynamic nature, these materials respond very well to directional fluid flow and assume long-range order on flat substrates. Persistence length, order, and packing o... |
15600305 | Nonracemic dopant-mediated hierarchical amplification of macromolecular helicity in a charged polyacetylene leading to a cholesteric liquid crystal in water. | Here we show the first example of a helical polyacetylene that forms a lyotropic liquid crystal (LC) through a hierarchical amplification of a macromolecular helicity process in water. The macromolecular helicity with an excess of one helical sense was first induced in the positively charged polyacetylene upon complexa... |
15618622 | Binding energy of tea catechin/caffeine complexes in water evaluated by titration experiments with 1H-NMR. | Evaluating the binding energy of a catechin/caffeine complex in water is important in order to elucidate the ability for molecular recognition of tea catechins. The results of this study revealed that the stoichiometric ratio of the complexation between tea chatechins (EGCg, ECg, EGC, and EC) and caffeine was 1:1 at le... |
15616163 | Purine receptors: GPCR structure and agonist design. | An integrated approach to the study of drug-receptor interactions has been applied to adenosine receptors (ARs) and P2Y nucleotide receptors. This approach includes probing the receptor structure through site-directed mutagenesis and molecular modeling, in concert with altering the structure of the agonist ligands. Goa... |
15562404 | The role of physical environment on molecular electromechanical switching. | The influences of different physical environments on the thermodynamics associated with one key step in the switching mechanism for a pair of bistable catenanes and a pair of bistable rotaxanes have been investigated systematically. The two bistable catenanes are comprised of a cyclobis(paraquat-p-phenylene) (CBPQT4+) ... |
15540268 | Convergent synthesis of platinum-acetylide dendrimers. | An efficient convergent route to the main chain type of organometallic dendrimers, in which platinum moieties are linked by 1,3,5-triethynylbenzene, has been developed. The synthesis of platinum-acetylide dendrons involved the use of two types of trialkylsilyl groups for protection of the terminal acetylene. The platin... |
15540260 | Aggregation of [Cu(II)4] building blocks into [Cu(II)8] clusters or a [Cu(II)4]infinity chain through subtle chemical control. | Coordination complexes of the ligand H3L [1,3-bis(3-oxo-3-phenylpropionyl)-2-hydroxy-5-methylbenzene] with Cu(II) are reported. Clusters showing various nuclearities or modes of supramolecular organization have been prepared by slightly changing the reaction conditions and have been crystallographically characterized. ... |
15532019 | Complete charge pooling is prevented in viologen-based dendrimers by self-protection. | We have investigated the electrochemical behavior, and chemical and photosensitized reduction of two dendrimers based on a 1,3,5-trisubstituted benzenoid core, which contain 9 and 21 4,4'-bipyridinium (usually called viologen) units, respectively, in their branches and are terminated with tetraarylmethane groups. For c... |
15532018 | Controllable donor-acceptor neutral [2]rotaxanes. | In pursuit of a neutral bistable [2]rotaxane made up of two tetraarylmethane stoppers--both carrying one isopropyl and two tert-butyl groups located at the para positions on each of three of the four aryl rings--known to permit the slippage of the pi-electron-donating 1,5-dinaphtho[38]crown-10 (1/5DNP38C10) at the ther... |
15526320 | Synthesis, spectroscopy, and electrochemistry of tetra-tert-butylated tetraazaporphyrins, phthalocyanines, naphthalocyanines, and anthracocyanines, together with molecular orbital calculations. | Tetraazaporphyrins (TAPs), phthalocyanines (Pcs), naphthalocyanines (Ncs), and anthracocyanines (Acs) with four tert-butyl groups attached at similar positions have been synthesized, and their electronic absorption, magnetic circular dichroism (MCD), IR, and voltammetric properties were studied and interpreted with the... |
15472935 | Multifunctionalization of synthetic polymer systems through self-assembly. | A straightforward methodology towards the replacement of covalent strategies for the synthesis of multifunctional synthetic materials with a self-assembling strategy that employs multiple noncovalent recognition units to attach multiple functional molecules to a polymeric scaffold is outlined. Design requirements, adva... |
15570017 | Xanthophylls and alpha-tocopherol decrease UVB-induced lipid peroxidation and stress signaling in human lens epithelial cells. | Epidemiological studies suggest that consumption of vegetables rich in the xanthophylls lutein (LUT) and zeaxanthin (ZEA) reduces the risk for developing age-related cataract, a leading cause of vision loss. Although LUT and ZEA are the only dietary carotenoids present in the lens, direct evidence for their photoprotec... |
15612734 | pH-triggered assembly of organometallic receptors for lithium ions. | The reaction of half-sandwich complexes of ruthenium, rhodium, and iridium with amino-substituted 3-hydroxy-2-pyridone ligands in aqueous solution gives monomeric O,O'-chelate complexes. Upon addition of base, the complexes assemble to form trimeric metallamacrocycles, as evidenced by NMR spectroscopy and single-crysta... |
15612724 | Perturbation of fluorescence by nonspecific interactions between anionic poly(phenylenevinylene)s and proteins: implications for biosensors. | The use of anionic water-soluble conjugated polymers (CPs) for sensing the presence of avidin by use of a biotin-modified fluorescence quencher was studied. The molecules involved in the study included poly[2-methoxy-5-(3'-propyloxysulfonate)-1,4-phenylenevinylene] with either lithium (Li+-MPS-PPV) or sodium (Na(+)-MPS... |
15612712 | Superbowl container molecules. | The design, chemical synthesis, guest binding, and self-assembly of tureen-shaped container molecules is presented. With a large noncollapsible interior and five external binding sites, each superbowl container host is shown to bind up to nine guest molecules in well-defined locations. |
15612709 | Threading-followed-by-shrinking protocol for the synthesis of a [2]rotaxane incorporating a Pd(II)-salophen moiety. | This communication describes a new protocol for the construction of [2]rotaxanes: "threading-followed-by-shrinking". This approach involves the threading of a rodlike unit through a crown ether-like macrocycle and then shrinking the size of the macrocycle's cavity through coordination of a transition-metal ion by a sal... |
15526330 | Structural investigation of the HIV-1 envelope glycoprotein gp160 cleavage site 3: role of site-specific mutations. | Proteolytic processing of HIV gp160 to produce gp120 and gp41 is performed by PC enzymes. This process is a prerequisite for the virus infectivity, since both gp120 and gp41 participate in the virus HIV-1 entry mechanism. The structure of the gp120/gp41 junction remains to be elucidated, and the structural features req... |
15583862 | Modulation of signal transduction through the cellular prion protein is linked to its incorporation in lipid rafts. | Because expressed at a significant level at the membrane of human T cells, we made the hypothesis that the cellular prion protein (PrPc) could behave as a receptor, and be responsible for signal transduction. PrPc engagement by specific antibodies was observed to induce an increase in cytosolic calcium concentration an... |
15609939 | Salt effects on the conformational behavior of 5-carboxy- and 5-hydroxy-1,3-dioxane. | The varied and essential involvement of metal ions and inorganic salts in biological and chemical processes motivated the present study where 5-carboxy- and 5-hydroxy-1,3-dioxanes are used as model frameworks for the evaluation of the conformational behavior of oxygen-containing receptors in the presence of Li(+), Na(+... |
15610857 | Structural basis for discriminative regulation of gene expression by adenine- and guanine-sensing mRNAs. | Metabolite-sensing mRNAs, or "riboswitches," specifically interact with small ligands and direct expression of the genes involved in their metabolism. Riboswitches contain sensing "aptamer" modules, capable of ligand-induced structural changes, and downstream regions, harboring expression-controlling elements. We repor... |
15609994 | Single-stranded adenine-rich DNA and RNA retain structural characteristics of their respective double-stranded conformations and show directional differences in stacking pattern. | The structural preorganization of isosequential ssDNA and ssRNA hexamers d/r(GAAAAC)(1) [J. Am. Chem. Soc. 2003, 125, 9948] have been investigated by NMR and molecular dynamics simulations. Analysis of the nuclear Overhauser effect spectrometry (NOESY) footprints in the aqueous solution has shown that there is a substa... |
15606102 | A multifunctional high-spin biradical pyrazolylbipyridine-bisnitronylnitroxide. | [structure: see text] Synthesis and UV-vis, IR, and EPR spectroscopic characterizations, together with X-ray structural analysis, of functional nitronyl- and iminonitroxides attached to pyrazolylbipyridine are described. The exchange interactions between the nitronylnitroxides are found to be stronger than for the imin... |
15606087 | Isomeric [2]rotaxanes and unidirectional [2]pseudorotaxane composed of alpha-cyclodextrin and aliphatic chain-linked carbazole-viologen compounds. | [structure: see text] Capping the alpha-cyclodextrin (alpha-CD) complex of 1-(N-carbazole)-10-[4-(4-pyridinio)-1-pyridinio]decane with 3,5-dimethoxybenzyl bromide in DMF gives two isomeric [2]rotaxanes, 2a and 2b, while alpha-CD and 1-(N-carbazole)-10-[4-(1-methyl-4-pyridnino)-1-pyridinio]decane 3 in water form mostly ... |
15606080 | Luminescent Tb3+ complex with pendant crown ether showing dual-component recognition of H+ and K+ at multiple pH windows. | [structure: see text] A lanthanide luminescent probe that was functionalized with quinoline-alkylated diaza-18-crown-6 showed dual-component recognition of concentrations of H+ and K+ at four independent pH ranges, including in the physiological pH window. Moreover, it exhibited pH- and [K+]-independent long-lived lant... |
15606175 | Paramagnetic precursors for supramolecular assemblies: selective syntheses, crystal structures, and electrochemical and magnetic properties of Ru2(O2CMe)4-n(formamidinate)nCl complexes, n = 1-4. | Reactions of Ru(2)(O(2)CMe)(4)Cl with two formamidines, HDXyl(2,6)F = N,N'-di(2,6-xylyl)formamidine and HDAniF = N,N'-di(p-anisyl)formamidine, have been investigated with the idea of synthesizing compounds with a mixed set of ligands having different labilities to be used as precursors of paramagnetic, higher-order ass... |
15606157 | Uranyl complexation by a schiff-base, polypyrrolic macrocycle. | Mononuclear uranyl (UO(2)(2+)) complexes supported by the polypyrrolic macrocycle L have been synthesized and exhibit hinged macrocyclic structures with an expanded cavity and enforced pi-stacking and hydrogen bonding motifs. |
15584762 | Diastereoselective self-assembly of chiral diamine-chelated aryllithiums to dimeric aggregates. | Aryllithium compounds [LiC6H4(CH2N(Et)CH2CH2NEt2)-2]2 (2b), [LiC6H4(CH(Me)N(Me)CH2CH2NMe2-(R))-2]2 ((R)-3b), and [LiC6H4(CH(Me)N(Me)CH2CH2NMe2-(rac))-2]2 ((rac)-3b) were synthesized and characterized in the solid state and in solution. X-ray crystallographic studies of 2b and (R)-3b and molecular weight determinations ... |
15584711 | Artificial ion channel formed by cucurbit[n]uril derivatives with a carbonyl group fringed portal reminiscent of the selectivity filter of K+ channels. | Novel artificial ion channels (1 and 2) based on CB[n] (n = 6 and 5, respectively) synthetic receptors with carbonyl-fringed portals (diameter 3.9 and 2.4 A, respectively) can transport proton and alkali metal ions across a lipid membrane with ion selectivity. Fluorometric experiments using large unilamellar vesicles s... |
15604402 | Building programmable jigsaw puzzles with RNA. | One challenge in supramolecular chemistry is the design of versatile, self-assembling building blocks to attain total control of arrangement of matter at a molecular level. We have achieved reliable prediction and design of the three-dimensional structure of artificial RNA building blocks to generate molecular jigsaw p... |
15602552 | Virtual screening of chemical libraries. | Virtual screening uses computer-based methods to discover new ligands on the basis of biological structures. Although widely heralded in the 1970s and 1980s, the technique has since struggled to meet its initial promise, and drug discovery remains dominated by empirical screening. Recent successes in predicting new lig... |
15600362 | Ambidentate pyridyl-carboxylate ligands in the coordination-driven self-assembly of 2D Pt macrocycles: self-selection for a single isomer. | The coordination-driven self-assembly of discrete 2D macrocyclic species from ambidentate pyridyl-carboxylate-based donor ligands and platinum-containing acceptors is presented. All these species are characterized by electrospray ionization mass spectrometry (ESIMS), multinuclear NMR, and in one example, X-ray crystall... |
15600351 | Grafted metallocalixarenes as single-site surface organometallic catalysts. | Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-Ti(IV) precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm(-2)).... |
15600348 | A new tripodal receptor for molecular recognition of monosaccharides. A paradigm for assessing glycoside binding affinities and selectivities by 1H NMR spectroscopy. | A new tripodal receptor for the recognition of monosaccharides is described. The prototypical host 1 features a 1,3,5-substituted 2,4,6-triethylbenzene scaffold bearing three convergent H-bonding units. The binding ability of the t-octyl derivative 1a toward a set of octylglycosides of biologically relevant monosacchar... |
15600341 | Aryl thiol substrate 3-carboxy-4-nitrobenzenethiol strongly stimulating thiol peroxidase activity of glutathione peroxidase mimic 2, 2'-ditellurobis(2-deoxy-beta-cyclodextrin). | Artificial glutathione peroxidase (GPx) model 2, 2'-ditellurobis(2-deoxy-beta-cyclodextrin) (2-TeCD) which has the desirable properties exhibited high substrate specificity and remarkably catalytic efficiency when 3-carboxy-4-nitrobenzenethiol (ArSH) was used as a preferential thiol substrate. The complexation of ArSH ... |
15600334 | Self-assembly of chiral DNA nanotubes. | A system of DNA "tiles" that is designed to assemble to form two-dimensional arrays is observed to form narrow ribbons several micrometers in length. The uniform width of the ribbons and lack of frayed edges lead us to propose that they are arrays that have curled and closed on themselves to form tubes. This proposal i... |
15600309 | Crystal-to-crystal guest exchange of large organic molecules within a 3D coordination network. | Single-crystal-to-single-crystal guest exchanges of large guest molecules [triphenylene (3a), anthracene (3b), perylene (3c), and triphenylphosphine oxide (3d)] were successfully performed in a large channel of a 3D coordination network (2) having a planar ligand, (1). Crystallographic analysis revealed efficient stack... |
15600302 | Polymetallic lanthanide complexes with PAMAM-naphthalimide dendritic ligands: luminescent lanthanide complexes formed in solution. | Generation 3 PAMAM dendrimers functionalized with 2,3-naphthalimide chromophoric groups on the end branches were synthesized, and the formation of Eu3+ polymetallic complexes was investigated. The luminescence properties of these complexes upon binding were fully characterized. On addition of Eu3+ to the dendrimer solu... |
15568857 | Electrochemical redox control of ferrocene using a supramolecular assembly of ferrocene-linked C(60) derivative and metallooctaethylporphyrin array on a Au(111) electrode. | Supramolecular assembled layers of ferrocene-linked C(60) derivative (C(60)Fc) and various metal ions coordinated to octaethylporphyrin (MOEP) were formed on the surface of a Au(111) single-crystal electrode by immersing the Au substrate successively into a benzene solution containing MOEP and one containing C(60)Fc mo... |
15598535 | Non-exhaustive extraction techniques (NEETs) for the prediction of naphthalene mineralisation in soil. | Non-exhaustive extraction techniques (NEETs) have been shown to measure the putatively bioavailable fraction of hydrophobic compounds in soil. To date, these studies have only considered bioavailability in a single soil type. In this study, naphthalene was amended into five different soil types and mineralisation, bact... |
15597801 | [Acute blood purification for septic multiple organ failure]. | Blood purification has been used for the prevention or treatment of septic multiple organ failure (MOF). Continuous renal replacement therapy (CRRT) is useful in the careful management of fluid, electrolytes, and acid-base balance and for the removal of metabolic wastes. Continuous plasma exchange (CPE) with CRRT is ap... |
15597782 | [Basic concept and definition of SIRS and sepsis--present consideration and future perspectives]. | SIRS (systemic inflammatory response syndrome) is thought to be caused by hypercytokinemia. On the other hand, interleukin-6 (IL-6) is reported to be one of most easily measurable cytokines and we found that IL-6 blood levels on SIRS patients are above 1,500 pg/ml which is compatible to the previously reported values. ... |
15595809 | Improvement in the luminescence properties and processability of LaF3/Ln and LaPO4/Ln nanoparticles by surface modification. | The surface of lanthanide(III)-doped LaPO4 nanoparticles was modified by reaction with an alcohol, leading to a covalent bond between the ligand and the particle surface. The surface of lanthanide(III)-doped LaF3 nanoparticles was modified to alter the solubility of the nanoparticles and study the influence of surface ... |
15595808 | Directed self-assembly of functionalized silica nanoparticles on molecular printboards through multivalent supramolecular interactions. | Silica nanoparticles functionalized with beta-cyclodextrin (CD) host molecules (5) have been prepared by reacting carboxylic active ester-terminated silica nanoparticles (4) with CD heptamine. Silica nanoparticles functionalized with glucosamine (6), having similar surface properties as 5 but lacking the host-guest rec... |
15595803 | Nontoxic block copolymer nanospheres: design and characterization. | Biodegradable polymers capable of self-assembly into hollow nanospheres of less than 100 nm have significant potential for biotechnology applications such as drug delivery and gene therapy. Here we describe the synthesis of a novel ABA-type triblock copolymer made from a hydrophobic tyrosine-derived core and two hydrop... |
15595786 | Versatility of aqueous micellar solutions for self-assembled monolayers engineering. | Self-assembly of aliphatic as well as aromatic thiol-terminated molecules was achieved onto a variety of gold surfaces using aqueous micellar solutions. Scanning tunneling microscopy experiments allowed us to demonstrate that the increase in the density of self-assembled monolayers (SAMs) prepared from micellar aqueous... |
15595751 | Hollow titania spheres with movable silica spheres inside. | We demonstrate a flexible method for preparing hollow TiO2 nanospheres with movable silica nanoparticles inside (HTNMSNs). In this method, we used monodisperse silica--polystyrene core--shell nanospheres (SiO2-PS-CSNs) sulfonated as templates and prepared the composite shell consisting of TiO2 and sulfonated polystyren... |
15595877 | Fluorescent sensor for imidazole derivatives based on monomer-dimer equilibrium of a zinc porphyrin complex in a polymeric film. | A new zinc(II) porphyrin conjugate with an appended pyrene subunit has been synthesized and shown to exhibit significant and analytical usefulness for fluorescence sensing toward imidazole derivatives. The molecular recognition was based on the bridging interaction of the imidazole ring of analyte with the zinc(II) cen... |
15590781 | Type V protein secretion pathway: the autotransporter story. | Gram-negative bacteria possess an outer membrane layer which constrains uptake and secretion of solutes and polypeptides. To overcome this barrier, bacteria have developed several systems for protein secretion. The type V secretion pathway encompasses the autotransporter proteins, the two-partner secretion system, and ... |
15589167 | A deficiency in Drak2 results in a T cell hypersensitivity and an unexpected resistance to autoimmunity. | DRAK2 is a member of the death-associated protein (DAP)-like family of serine/threonine kinases. Members of this family induce apoptosis in various cell types. DRAK2, in particular, is specifically expressed in T cells and B cells, and it is differentially regulated during T cell development. To determine whether DRAK2... |
15543646 | Enatiomeric analysis of simendan by CE with beta-CD as chiral selector compared with CMPA-HPLC. | The chiral separation of simendan enantiomers using capillary electrophoresis was studied with beta-cyclodextrin (beta-CD) as chiral selector. The influences of the concentration and pH of borate buffer solution, beta-CD concentration and methanol content in the background electrolyte were investigated. These factors w... |
15386577 | Study on the enantiomeric ratio of the pharmaceutical substances alkannin and shikonin. | The chiral pair alkannin and shikonin (A/S) are potent pharmaceutical substances with a wide spectrum of biological activity; their enantiomeric ratio does not influence the major biological activity studied hitherto. Nevertheless, in pharmaceutical development and approval of chiral drugs from the Health and Regulator... |
15589807 | Aggregation states and molecular motion of polymer ultrathin films prepared at the air/water interface. | Surface structure and dynamics in three different polymeric ultrathin systems, such as organosilane monolayers, poly(methyl methacrylate) (PMMA) brushes and poly(amido amine) dendrimer monolayers are discussed. |
15589806 | Molecular and nanoscale materials and devices in electronics. | Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules ... |
15571410 | Self-assembly and molecular recognition of a luminescent gold rectangle. | A luminescent molecular rectangle [Au(4)(micro-PAnP)(2)(micro-bipy)(2)](OTf)(4) (1.(OTf)(4)) (PAnP = 9,10-bis(diphenylphosphino)anthracene, bipy = 4,4'-bipyridine, X = NO(3)(-) or OTf(-)), synthesized from the self-assembly of the molecular "clip" Au(2)(micro-PAnP)(OTf)(2) and bipy, shows a large rectangular cavity of ... |
15585831 | Cutting edge: CD28-mediated transcriptional and posttranscriptional regulation of IL-2 expression are controlled through different signaling pathways. | Despite the clear functional importance of CD28 costimulation, the signaling pathways transduced through CD28 have remained controversial. PI3K was identified early as a candidate for CD28 signaling, but conflicting data during the past decade has left the role of PI3K unresolved. In this report, we have resolved this ... |
15584753 | Extraction of Au nanoparticles having narrow size distributions from within dendrimer templates. | Here, we show that Au nanoparticles having diameters of less than 2.2 nm can be extracted from within the interior of PAMAM dendrimers using n-alkanethiol extractants. Extraction proceeds quickly, regardless of the size of the nanoparticle, the dendrimer generation, or the peripheral functionalization of the dendrimer.... |
15584742 | Calix[4]pyrrole[2]carbazole: a new kind of expanded calixpyrrole. | The synthesis and anion binding properties of a new class of calixpyrrole analogue, containing two carbazole subunits in lieu of two of the four acetone bridging elements normally found in calix[4]pyrrole, is described. The compound exists in a winglike structure in the solid state, as judged from single-crystal X-ray ... |
15582538 | Cholesterol modulates maculosin's orientation in model systems of biological membranes. Relevance towards putative molecular recognition. | Fluorescence techniques were used to study (1) the extent of insertion of the bioactive cyclic dipeptide cyclo(l-tyrosyl-l-prolyl), maculosin, in model systems of membranes of 1, 2-palmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl choline (POPC), (2) its in-depth locat... |
15583167 | Phycobilisome rod mutants in Synechocystis sp. strain PCC6803. | The phycobilisome is a large pigment-protein assembly that harvests light energy for photosynthesis. This supramolecular complex is composed of two main structures: a core substructure and peripheral rods. Linker polypeptides assemble phycobiliproteins within these structures and optimize light absorption and energy tr... |
15583017 | T cell cross-reactivity and conformational changes during TCR engagement. | All thymically selected T cells are inherently cross-reactive, yet many data indicate a fine specificity in antigen recognition, which enables virus escape from immune control by mutation in infections such as the human immunodeficiency virus (HIV). To address this paradox, we analyzed the fine specificity of T cells r... |
15583013 | Crucial role for ecto-5'-nucleotidase (CD73) in vascular leakage during hypoxia. | Extracellular adenosine has been widely implicated in adaptive responses to hypoxia. The generation of extracellular adenosine involves phosphohydrolysis of adenine nucleotide intermediates, and is regulated by the terminal enzymatic step catalyzed by ecto-5'-nucleotidase (CD73). Guided by previous work indicating that... |
15583011 | Apoptotic cells with oxidation-specific epitopes are immunogenic and proinflammatory. | Oxidation of low density lipoprotein (LDL) generates a variety of oxidatively modified lipids and lipid-protein adducts that are immunogenic and proinflammatory, which in turn contribute to atherogenesis. Cells undergoing apoptosis also display oxidized moieties on their surface membranes, as determined by binding of o... |
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