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Two crystalline modifications (Ia and Ib) of the polynuclear thallium (I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}] n have been synthesized and characterized by CP/MAS NMR (13C, 31P). From full 31P CP/MAS NMR... more
Two crystalline modifications (Ia and Ib) of the polynuclear thallium (I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}] n have been synthesized and characterized by CP/MAS NMR (13C, 31P). From full 31P CP/MAS NMR spectra, the χ2 plots were constructed to calculate the 31P chemical shift anisotropy 31P − δaniso = (δzz − δiso) and asymmetry parameters η = (δ yy − δ
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Godkänd; 2006; 20070122 (ysko)</p
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Abstract Crystalline bismuth(III) dithiocarbamato-chlorido complexes [Bi{S 2 CN(C 3 H 7 ) 2 }Cl 2 ] ( I ) and [Bi{S 2 CN( iso- C 4 H 9 ) 2 } 2 Cl] ( II ) were prepared and comparatively studied by ( 13 C, 15 N) CP-MAS NMR spectroscopy, IR... more
Abstract Crystalline bismuth(III) dithiocarbamato-chlorido complexes [Bi{S 2 CN(C 3 H 7 ) 2 }Cl 2 ] ( I ) and [Bi{S 2 CN( iso- C 4 H 9 ) 2 } 2 Cl] ( II ) were prepared and comparatively studied by ( 13 C, 15 N) CP-MAS NMR spectroscopy, IR spectroscopy, and X-ray diffraction (CIF files CCDC nos. 1971976 and 1971975, respectively). The dithiocarbamate ligands are typically coordinated in the S,S'- iso- ( I ) or aniso- ( II ) bidentate-terminal mode. In each of the compounds, neighboring molecules are connected through one or two μ 2 -Cl – ligands into zigzag-like polymer chains, in which the central atom has sixfold coordination: [BiS 2 Cl 4 ] ( I ) or [BiS 4 Cl 2 ] ( II ). The binding unit in the polymer chains of I is a four-membered [Bi–(μ-Cl) 2 –Bi] metallocycle in the butterfly conformation (the dihedral angle is 140.51(3)°). Therefore, stronger binding of heteroleptic molecules in polymer chains leads to a considerably shorter interatomic Bi–Bi distances in I (4.0904(4) Å) than in II (4.8772(4) Å). The thermal behavior of heteroleptic bismuth(III) complexes was studied by simultaneous thermal analysis with recording of TG and DSC curves. Although the major product of thermal transformations of I and II is Bi 2 S 3 , the microprobe method also identified the presence of reduced bismuth and BiCl 3 .
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Abstract Two polymorphs of a new mercury(II) N,N-dipropyldithiocarbamate represented by centrosymmetric binuclear and pseudo-binuclear molecules, [Hg2(PrDtc)4] (1) and [Hg(PrDtc)2]2 (2), have been isolated, identified using heteronuclear... more
Abstract Two polymorphs of a new mercury(II) N,N-dipropyldithiocarbamate represented by centrosymmetric binuclear and pseudo-binuclear molecules, [Hg2(PrDtc)4] (1) and [Hg(PrDtc)2]2 (2), have been isolated, identified using heteronuclear (13C, 15N) CP-MAS NMR and structurally characterised by single-crystal X-ray diffraction analysis. There are two pairs of inequivalent PrDtc ligands playing either terminal chelating or tridentate bridging structural functions in the former compound; while the latter complex comprises two pairs of structurally inequivalent chelating PrDtc ligands. The reaction of freshly precipitated mercury(II) N,N-dipropyldithiocarbamate (HgPrDtc) with a [AuCl4]−/2 M HCl solution results in the formation of the ionic complex [Au(PrDtc)2]2[Hg2Cl6] (3). There are two inequivalent centrosymmetric cations, [Au(PrDtc)2]+ (‘A’ and ‘B’), and a binuclear centrosymmetric anion, [Hg2Cl6]2− in the structure of 3. In the cationic part of the complex, each of the gold(III) cations has two pairs of the relatively weak inequivalent secondary Au···S bonds with two neighbours, therefore forming linear supramolecular cationic chains (⋯‘A’⋯‘B’⋯‘A’⋯‘B’⋯)n. To study the thermal behaviour of the compounds, simultaneous thermal analysis was also performed. The formation of HgS and reduced elemental gold was established during the thermolysis of 1/2 and 3, respectively.
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Research Interests: Biochemistry, Chemistry, Crystallography, Electron Microscopy, Quantum Theory, and 14 moreNuclear Magnetic Resonance, Scanning Electron Microscopy, Atomic Force Microscopy, Medicine, Humans, Carbon Isotopes, Protein Secondary Structure Prediction, Amino Acid Sequence, Structure activity Relationship, Alzheimer Disease, Biochemistry and cell biology, Electron Microscope, Molecular Sequence Data, and Medical biochemistry and metabolomics
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ABSTRACT
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The nickel(II) and copper(II) complexes [M{S 2 P(OR) 2 } 2 ] (M = Ni, 6 3 Cu, 6 5 Cu; R = C 2 H 5 , C 3 H 7 , i-C 3 H 7 , C 4 H 9 , i-C 4 H 9 , s-C 4 H 9 , i-C 5 H 1 1 , c-C 6 H 1 1 ) with eight symmetric O,O'-dialkyl... more
The nickel(II) and copper(II) complexes [M{S 2 P(OR) 2 } 2 ] (M = Ni, 6 3 Cu, 6 5 Cu; R = C 2 H 5 , C 3 H 7 , i-C 3 H 7 , C 4 H 9 , i-C 4 H 9 , s-C 4 H 9 , i-C 5 H 1 1 , c-C 6 H 1 1 ) with eight symmetric O,O'-dialkyl phosphorodithioates were synthesized, and their structures and spectral properties were studied by EPR and CP/MAS 1 3 C and 3 1 P NMR. As determined by EPR, the [CuS 4 ] chromophores in the lattice of nickel(II) complexes have predominantly a square-planar structure. The chromophores in complexes with phosphorodithioate ligands incorporating bulky alkyl substituents have somewhat distorted geometries. NMR shows that the Dtph groups in most nickel(II) complexes are structurally equivalent. An exception is [Ni {S 2 P(OC 3 H 7 ) 2 } 2 ], which gives rise to two (1: 1) 3 1 P NMR signals. For [Ni(S 2 P(O-i-C 4 H 9 ) 2 } 2 ], the a and β modifications were obtained. In the a modification, the phosphorodithioate groups are nonequivalent, whereas the β modification has structurally equivalent ligands. The broadening of the 3 1 P NMR signal of the [Ni{S 2 P(O-s-C 4 H 9 ) 2 } 2 ] complex is rationalized by the existence of six optical isomers (due to two chiral centers in each of the ligands). For the Dtph groups acting as bidentate terminal ligands in the nickel(II) complexes, the 3 1 P chemical shift anisotropy δ a n i s o and asymmetry parameter η were calculated from experimental NMR spectra. Single-crystal X-ray diffraction shows that bis(O,O'-dipropyl phosphorodithioato)nickel(II) exists in the form of two centrosymmetric molecules. In the structure of α-bis(O,O'-dipropyl phosphorodithioato)nickel(II), the Dtph ligands in the molecule are nonequivalent. The experimental 3 1 P NMR signals in the spectra of [Ni{S 2 P(OC 3 H 7 ) 2 } 2 ] and a-[Ni{S 2 P(O-i-C 4 H 9 ) 2 } 2 ] are assigned to the structural positions of phosphorus atoms in the corresponding molecular structures determined by X-ray diffraction.
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The structural reorganization of bis-(diethyldithiocarbamato)-pyridine-zinc(II) and -copper(II) in the process of clathration with CCl4 molecules on ESR, solid state natural abundance C-13 and N-15CP/MAS NMR spectroscopy and single... more
The structural reorganization of bis-(diethyldithiocarbamato)-pyridine-zinc(II) and -copper(II) in the process of clathration with CCl4 molecules on ESR, solid state natural abundance C-13 and N-15CP/MAS NMR spectroscopy and single crystal X-ray diffraction data
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Abstract Acetate-functionalized silica membranes were prepared via co-condensation. The molar ratio of functional groups in the silica matrix was varied in the range of 0–0.6, denoted by x. The presence of functional groups bonded to the... more
Abstract Acetate-functionalized silica membranes were prepared via co-condensation. The molar ratio of functional groups in the silica matrix was varied in the range of 0–0.6, denoted by x. The presence of functional groups bonded to the silica network was revealed by FTIR and 29 Si and 13 C solid-state NMR analysis. The stability of the groups was studied by TG analysis. The membranes were evaluated for CO 2 /N 2 mixture separation in a temperature range of 253–373 K using a feed pressure of 9 bar and a sweep gas kept at atmospheric pressure on the permeate side. The membranes were found to be CO 2 -selective at all the conditions studied. The highest observed selectivity was 16 for x=0.4, with a CO 2 permeance of 5.12×10 −7 mol s −1 m −2 Pa −1 . For x=0.2, a permeance of as high as 20.74×10 −7 mol s −1 m −2 Pa −1 with a CO 2 /N 2 selectivity of 7.5 was obtained. This permeance is the highest reported for CO 2 /N 2 separation using functionalized silica membranes. It is proposed that the separation mechanism between CO 2 and N 2 was the preferential adsorption of CO 2 , which inhibited adsorption and permeation of N 2 through the silica pore network. Permporometry results revealed that as the loading of functional groups increased, the He permeance decreased. It was also indicated that the quantity of micropores in the functionalized membrane was higher than that in the parent silica membrane.
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The sorption of Inositol hexaphosphate (IP6) onto gibbsite was investigated using a combination of adsorption experiments, (31)P solid-state MAS NMR spectroscopy, and surface complexation modeling. Adsorption experiments conducted at four... more
The sorption of Inositol hexaphosphate (IP6) onto gibbsite was investigated using a combination of adsorption experiments, (31)P solid-state MAS NMR spectroscopy, and surface complexation modeling. Adsorption experiments conducted at four temperatures showed that IP6 sorption decreased with increasing pH. At pH 6, IP6 sorption increased with increasing temperature, while at pH 10 sorption decreased as the temperature was raised. (31)P MAS NMR measurements at pH 3, 6, 9 and 11 produced spectra with broad resonance lines that could be de-convoluted with up to five resonances (+5, 0, -6, -13 and -21ppm). The chemical shifts suggest the sorption process involves a combination of both outer- and inner-sphere complexation and surface precipitation. Relative intensities of the observed resonances indicate that outer-sphere complexation is important in the sorption process at higher pH, while inner-sphere complexation and surface precipitation are dominant at lower pH. Using the adsorption and (31)P MAS NMR data, IP6 sorption to gibbsite was modeled with an extended constant capacitance model (ECCM). The adsorption reactions that best described the sorption of IP6 to gibbsite included two inner-sphere surface complexes and one outer-sphere complex: ≡AlOH + IP₆¹²⁻ + 5H⁺ ↔ ≡Al(IP₆H₄)⁷⁻ + H₂O, ≡3AlOH + IP₆¹²⁻ + 6H⁺ ↔ ≡Al₃(IP₆H₃)⁶⁻ + 3H₂O, ≡2AlOH + IP₆¹²⁻ + 4H⁺ ↔ (≡AlOH₂)₂²⁺(IP₆H₂)¹⁰⁻. The inner-sphere complex involving three surface sites may be considered to be equivalent to a surface precipitate. Thermodynamic parameters were obtained from equilibrium constants derived from surface complexation modeling. Enthalpies for the formation of inner-sphere surface complexes were endothermic, while the enthalpy for the outer-sphere complex was exothermic. The entropies for the proposed sorption reactions were large and positive suggesting that changes in solvation of species play a major role in driving the sorption process.
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Dithiophosphate zinc(II) complexes with eight different O,O′-dialkyldithiophosphate ligands have been prepared in solid/liquid states and as surface complexes on a synthetic sphalerite, and studied by means of 31P NMR spectroscopy. All... more
Dithiophosphate zinc(II) complexes with eight different O,O′-dialkyldithiophosphate ligands have been prepared in solid/liquid states and as surface complexes on a synthetic sphalerite, and studied by means of 31P NMR spectroscopy. All 31P resonances, corresponding to dithiophosphate ligands with different structural functions (i.e. terminal chelating or bridging between two metal atoms in bi- and tetranuclear complexes), have been assigned on the basis of comparative analyses of chemical shift data for solid complexes, their melts and chloroform solutions at various concentrations. The bridging coordination of O,O′-dialkyldithiophosphate ligands by the two neighbouring zinc(II) atoms was established in the case of zinc(II) complexes formed at the surface of the synthetic sphalerite. In addition, novel molecular and crystal structures of the binuclear O,O′-di-cyclo-hexyldithiophosphate zinc(II) complex have been resolved by single-crystal X-ray diffraction data analysis, and useful correlations with 31P NMR data for this complex were obtained.
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The adduct of bis (diethyldithiocarbamato) zinc (II) with pyridine, Zn (EDtc) 2· Py, was prepared and studied by means of ESR (63Cu2+ and 65Cu2+ were used as spin labels), solid-state natural abundance 13C and 15N CP/MAS NMR spectroscopy... more
The adduct of bis (diethyldithiocarbamato) zinc (II) with pyridine, Zn (EDtc) 2· Py, was prepared and studied by means of ESR (63Cu2+ and 65Cu2+ were used as spin labels), solid-state natural abundance 13C and 15N CP/MAS NMR spectroscopy and single-...
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ABSTRACT Adsorption of diphenyl-, phenyl- and orthophosphate on γ-Al2O3 was studied with a combination of macroscopic and 31P solid-state NMR measurements. Results for adsorption suggest that diphenyl phosphate was bound largely as an... more
ABSTRACT Adsorption of diphenyl-, phenyl- and orthophosphate on γ-Al2O3 was studied with a combination of macroscopic and 31P solid-state NMR measurements. Results for adsorption suggest that diphenyl phosphate was bound largely as an outer-sphere complex, while phenyl phosphate was held largely as inner-sphere surface complexes with an outer-sphere complex present only at higher pH values. Both the adsorption edge and the cross polarization magic angle spinning NMR spectra were consistent with the interaction between the surface and phenyl phosphate being driven by electrostatic forces. Adsorption of orthophosphate was more complex, with evidence of outer- and inner-sphere complexes and surface precipitation. Increasing the orthophosphate concentration and equilibration time tended to increase the fraction bound as a surface precipitate.
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Research Interests: Chemistry, Crystallography, Biophysical Chemistry, Magnetic Resonance Spectroscopy, Solid State NMR, and 14 moreSequence Analysis, Molecular modeling, Biological Sciences, Humans, Computer Simulation, Carbon Isotopes, Physical sciences, Peptide, CHEMICAL SCIENCES, Protein Secondary Structure Prediction, Protein Conformation, Amino Acid Sequence, Alzheimer Disease, and Molecular Sequence Data
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Research Interests: Chemistry, Crystallography, Carbon, Nuclear Magnetic Resonance, Biophysical Chemistry, and 15 moreMagnetic Resonance Spectroscopy, Medicine, Biological Sciences, Humans, Physical sciences, Nearest Neighbor, Peptides, CHEMICAL SCIENCES, Protein Secondary Structure Prediction, Protein Conformation, Radiofrequency, Electric Dipole Moments, Alzheimer Disease, Full Length Movies, and Magic Angle Spinning
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Research Interests: Chemistry, Physical Chemistry, Crystallography, Lithium, Biophysical Chemistry, and 15 moreMagnetic Resonance Spectroscopy, Medicine, Macromolecular X-Ray Crystallography, Biological Sciences, DNA, Phosphorus, Magnesium, Stereochemistry, Physical sciences, CHEMICAL SCIENCES, Sodium, Phosphate, Netropsin, Nucleic Acid Conformation, and Magic Angle Spinning
Research Interests: Chemistry, Crystallography, Scanning Electron Microscopy, Transmission Electron Microscopy, Scanning Transmission Electron Microscopy, and 10 moreMagnetic Resonance Spectroscopy, Atomic Force Microscopy, Medicine, Humans, Neurotoxins, Amino Acid Sequence, Alzheimer Disease, Electron Paramagnetic Resonance, Amyloidosis, and Molecular Sequence Data
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Polymorphism of Amyloid Fibrils and Aggregation Kinetics of Alzheimer's Abeta peptides : solid state NMR, EM and AFM studies
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Morphlogy and growth kinetics of Alzheimer's amyloid beta-peptides, Aβ(1-40) and the Arctic mutation Aβ(1-40)(E22G) : in situ atomic force microscopy study
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It is believed that Alzheimer's disease (AD) amyloid-β-peptide (Aβ) deposits contribute directly to the disease's progressive neurodegeneration. Aggregation cascade for Aβ peptides, its relevance t ...
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The spatial structure of Alzheimer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s amyloid Aβ10-35-NH2 peptide in... more
The spatial structure of Alzheimer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s amyloid Aβ10-35-NH2 peptide in aqueous solution at pH 7.3 and in SDS micelles was investigated by use of a combination of the residual dipolar coupling method and two-dimensional NMR spectroscopy (TOCSY, NOESY). At pH 7.3 Aβ10-35-NH2 adopts a compact random-coil conformation whereas in SDS micellar solutions two helical regions (residues 13-23 and 30-35) of Aβ10-35-NH2 were observed. By use of experimental data, the structure of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;peptide-micelle&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; complex was determined; it was found that Aβ10-35-NH2 peptide binds to the micelle surface at two regions (residues 17-20 and 29-35).
Research Interests: Chemistry, Spectroscopy, Medicine, Micelle, Micelles, and 12 morePeptide, Solutions, Protein Conformation, Amino Acid Sequence, Aqueous Solution, Hydrogen-Ion Concentration, Peptide conformation, Nuclear Magnetic Resonance Spectroscopy, Molecular Sequence Data, Cell Membrane, Sodium Dodecyl Sulfate, and random coil
Research Interests: Biophysics, Chemistry, Diffusion, Peptide, CHEMICAL SCIENCES, and 3 moreLipid Raft, Elsevier, and Raft
We present a (31)P NMR spectroscopy study of planar glass-plate-oriented multi-bilayers of dimyristoylphosphatidylcholine (DMPC) with addition of polyethylene oxide (PEO). This work revealed the presence of a new component in the spectra... more
We present a (31)P NMR spectroscopy study of planar glass-plate-oriented multi-bilayers of dimyristoylphosphatidylcholine (DMPC) with addition of polyethylene oxide (PEO). This work revealed the presence of a new component in the spectra that appeared only with addition of a small fraction of PEO (up to one PEO segment per dimyristoylphosphatidylcholine molecule) and disappeared when larger amounts of PEO were added. We explained this phenomenon as an effect of an inhomogeneous force field induced by the PEO molecules located at a certain depth in the lipid membrane interface region.
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The use of wear-resistant non-ferrous and lightweight materials calls for novel types of lubricants including neat Ionic Liquids (ILs) and ILs as additives to base oils [1-4]. ILs are non-flammable ...
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ABSTRACT Polyacrylic acid (PAA) is a promising polymer for engineering lipid-based drug-delivery vesicles. Its unique properties allow lowering drug dose and delivery the drug close to the site of its release. To design a successful... more
ABSTRACT Polyacrylic acid (PAA) is a promising polymer for engineering lipid-based drug-delivery vesicles. Its unique properties allow lowering drug dose and delivery the drug close to the site of its release. To design a successful delivery scheme, however, it is important to understand on the molecular scale how the polymer interacts with lipids under various conditions in the human body. Some aspects of the PAA-lipid interaction can be revealed using physical methods, such as differential scanning microscopy, nuclear magnetic resonance spectroscopy, NMR-diffusometry, and infrared spectroscopy. This work discusses the use of these techniques as well as the peculiarities of preparing vesicular and microscopically aligned PAA-lipid systems.
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A 10-residue peptide segment of β-lactoglobulin (β-LG11–20) forms amyloid-like fibrils as revealed by AFM, NMR, and MD simulations.