Poly[μ-(1,3-dihy­droxy­propan-2-olato)-potassium]

The asymmetric unit of the title compound, [K(C3H7O3)]n or K[H2gl]n, common name potassium glycerolate, contains half the K+ cation and half of the glycerolate anion. The other half of the anion is generated through a mirror plane passing through the K atom, and a C, an H and an O atom of the glycerolate ligand. The K+ ion is coordinated by the O atoms of the OH groups, leading to a six-membered chelate ring that adopts a very distorted boat conformation. The negatively charged O atom of the glycerolate anion, [H2gl−], is found in the flagpole position and forms an ionic bond with the K+ ion. The O atoms of the hydroxo groups are coordinated to two K+ ions, whereas the negatively charged O atom is bonded to one K+ ion. The K+ ion is coordinated by three other symmetry-related monodentate H2gl− ligands, so that each H2gl− ligand is bonded to two K+ ions, and the potassium has a seven-coordinate environment. The H2gl− ligands are connected via a strong O—H⋯O hydrogen bond and, together with the K⋯O inter­connections, form polymeric sheets which propagate in the directions of the a and b axes

Poly[μ-2,3-dihydroxy­propan-1-olato-sodium]

The Na+ cation in the title compound, [Na(C3H7O3)]n or Na[H2gl], is coordinated by five O atoms leading to a distorted trigonal-bipyramidal geometry. The negatively charged O atom of the glycerolate anion is in an equatorial position, and the O atom of the hydroxo group, attached to the secondary C atom, occupies an axial position completing a five-membered non-planar chelate ring; this defines the asymmetric unit. The Na+ cation is coordinated by three other symmetry-related monodentate H2gl− ligands, so that each H2gl− ligand is bonded to four Na+ ions. The H2gl− ligands are connected via strong O—H⋯O hydrogen bonds and these, together with the Na⋯O inter­connections, are responsible for the formation of polymeric sheets which propagate in the directions of the b and c axes

Cyclo­linopeptide B methanol tris­olvate

The title compound, C56H83N9O9S·3CH3OH, is a methanol tris­olvate of the cyclo­linopeptide cyclo(Met1—Leu2—Ile3—Pro4—Pro5—Phe6—Phe7—Val8—Ile9) (henceforth referred to as CLP-B), which was isolated from flaxseed oil. All the amino acid residues are in an l-configuration based on the CORN rule. The cyclic nona­peptide exhibits eight trans peptide bonds and one cis peptide bond observed between the two proline residues. The conformation is stabilized by an α-turn and two consecutive β-turns each containing a N—H⋯O hydrogen bond between the carbonyl group O atom of the first residue and the amide group H atom of the fourth (α-turn) or the third residue (β-turns), repectively. In the crystal, the components of the structure are linked by N—H⋯O and O—H⋯O hydrogen bonds into chains parallel to the a axis

Cyclo­linopeptide K butanol disolvate monohydrate

The title compound, C56H83N9O11S·2C4H10O·H2O, is a butanol–water solvate of the cyclo­linopeptide cyclo(Metsulfone1-Leu2–Ile3–Pro4–Pro5–Phe6–Phe7–Val8–Ile9) (henceforth referred to as CLP-K) which was isolated from flax oil. All the amino acid residues are in an l configuration based on the CORN rule. The cyclic nona­peptide exhibits eight trans peptide bonds and one cis peptide bond observed between the two proline residues. The conformation is stabilized by an α- and a β-turn, each containing an N—H⋯O hydrogen bond between the carbonyl group O atom of the first residue and the amide group H atom of the fourth (α-turn) and the third residue (β-turn), repectively. In the crystal, the components of the structure are linked by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds into a two-dimensional network parallel to (001). The –C(H2)OH group of one of the butanol solvent mol­ecules is disordered over two sets of sites with refined occupancies of 0.863 (4) and 0.137 (4)

Spontaneous Ag-Nanoparticle Growth at Single-Walled Carbon Nanotube Defect Sites: A Tool for In Situ Generation of SERS Substrate

Silver nanoparticles were spontaneously formed on pristine and oxidized single-wall nanotubes. Nanoparticles were observed on carbon nanotubes with AFM, and the presence of Ag nanoparticles were confirmed by ESR experiments. Raman spectroscopy of the Ag-treated carbon nanotubes had a 4–10X enhancement of intensity compared to untreated carbon nanotubes. Ag nanoparticles formed at defect sites on the CNT surface, where free electrons located at the defect sites reduced Ag+ to Ag. A mechanism for the propagation of the nanoparticles is through a continual negative charge generation on the nanoparticle by electron transfer from doublet oxygen (O2−)

A combined solid-state 17O NMR, crystallographic, and computational study of oxiranes

We report the synthesis and solid-state 17O NMR characterization of three 17O-labeled oxiranes: (2S*,3S*)-2,3-bis(4-nitrophenyl)-[17O]oxirane, (2S*,3R*)-2,3-bis(4-nitrophenyl)-[17O]oxirane, and 2,2,3-triphenyl-[17O]oxirane. In addition, we have determined the crystal structure of (2S*,3R*)-2,3-bis(4-nitrophenyl)oxirane by X-ray crystallography. When the experimentally determined 17O NMR tensors for oxiranes (where the C–O–C bond angle is about 60°) are compared with those for dimethyl ether (where the C–O–C bond angle is 113°) and other R–O–R′ functional groups, we found that the highly constrained geometry of oxiranes results in distinct tensor orientations in the molecular frame of reference. The experimental results are complemented by quantum chemical computations. This study represents the first time that 17O chemical shift and quadrupole coupling tensors are simultaneously determined for oxirane compounds.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author