LC Tissue Distribution Study of Paeonol in Rats after Oral Administration

Paeonol, an important constituent of the traditional Chinese medicine Cortex Moutan, has a variety of bioactivity. A simple and sensitive HPLC?CUV method has been developed for analysis of paeonol in different rat tissue (heart, liver, spleen, lung, kidney, and brain). Bio-samples were prepared by simple protein precipitation, and separation of paeonol was achieved on a C₁₈ column with methanol?C2% glacial acetic acid solution 70:30 (v/v) as mobile phase at a flow rate of 1.0 mL min^?1. UV detection was at 274 nm and the column temperature was 30 °C. Linearity was good between 0.025 and 5.0 ??g mL^?1 (r ² ?? 0.9990) for tissue samples. Inter-day and intra-day accuracy (as relative error, RE) and precision (as relative standard deviation, RSD) were <5.94 and 6.05%, respectively. The limit of detection was 0.025 ??g mL^?1 and extraction recovery for all samples was ??85.86%. The method was successfully applied to a tissue-distribution study after oral administration of 40 mg kg^?1 paeonol to healthy Sprague?CDawley rats. The study showed that paeonol was quickly distributed and eliminated after oral administration; liver and kidney were the major distribution tissues of paeonol in rats, and paeonol quickly passed through the blood?Cbrain barrier. It was also found there was no long-term accumulation of paeonol in rat tissues.     

Controllable synthesis, magnetism and solubility enhancement of graphene nanosheets/magnetite hybrid material by covalent bonding

Hybrids of Fe(3)O(4) nanoparticles and surface-modified graphene nanosheets (GNs) were synthesized by a two-step process. First, graphene nanosheets were modified by SOCl(2) and 4-aminophenoxyphthalonitrile to introduce nitrile groups on their surface. Second, the nitrile groups of surface-modified graphene nanosheets were reacted with ferric ions on the surface of Fe(3)O(4) with the help of relatively high boiling point solvent ethylene glycol to form a GNs/Fe(3)O(4) hybrid. The covalent attachment of Fe(3)O(4) nanoparticles on the graphene nanosheet surface was confirmed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDS) and scanning electron microscopy (SEM). TEM and HRTEM observations indicated that the sizes of the nanoparticles and their coverage density on GNs could be easily controlled by changing the concentration of the precursor and the weight ratio to GNs. Magnetic measurements showed that magnetization of the hybrid materials is strongly influenced by the reaction conditions. Chemically bonded by phthalocyanine, the solubility of as-synthesized GNs/Fe(3)O(4) hybrid materials was greatly enhanced, which was believed to have potential for applications in the fields of composites, wastewater treatment and biomaterials.     

Synthesis of 3D porous ferromagnetic NiFe2O4 and using as novel adsorbent to treat wastewater

Three dimensions (3D) porous NiFe(2)O(4) is synthesized by a sol-gel method using egg white. The obtained NiFe(2)O(4) shows both good ferromagnetic properties and high adsorption capacity. The porous NiFe(2)O(4) shows good adsorption properties for organic dyes (Methylene Blue (138.50 mg/g), Fuchsine Red (14.61 mg/g), Methyl Violet (19.06 mg/g)) and heavy metal ions (Cu (II) (55.83 mg/g), Cr (VI) (36.95 mg/g) and Ni (II) (37.02 mg/g)) due to its 3D interconnected porous structure. The maximum adsorption of Methylene Blue (MB) fit the pseudo-second-order model and Langmuir isotherm equation well. More interestingly, the ferromagnetic NiFe(2)O(4) can be separated under a magnetic field conveniently and keeps high removal efficiency (>97%) during seven reusable cycles. These results suggest that the porous NiFe(2)O(4) is a promising favorable and reusable adsorbent.     

Novel calcium-alginate capsules with aqueous core and thermo-responsive membrane

Novel calcium-alginate (Ca-alginate) capsules with aqueous core and thermo-responsive membrane are successfully prepared by introducing a co-extrusion minifluidic approach, and the thermo-responsive gating characteristics of Ca-alginate capsule membranes embedded with poly(N-isopropylacrylamide) (PNIPAM) microspheres are investigated systematically. The experimental results show that the prepared Ca-alginate capsules are highly monodisperse, and the average diameter and membrane thickness of Ca-alginate capsules are about 2.96 mm and 0.11 mm respectively. The Ca-alginate capsule membranes exhibit desired thermo-responsive gating property. With increasing the content of PNIPAM microspheres embedded in the Ca-alginate capsule membranes, the thermo-responsive gating coefficient of the capsule membranes increases simply. When solute molecules diffuse through the capsule membrane, the thermo-responsive gating coefficient is significantly affected by the molecular weight of solute molecules.     

Theoretical study on two types of weak interactions between methylenecyclopropane and XY (X,Y = H,F, Cl,and Br)

We present theoretical evidence that the two types of interactions exist in the complexes formed between methylenecyclopropane (MECP) and XY (X, Y = H, F, Cl, and Br). Two seats of XY interacted with MECP are located: (a) is via the pseudo‐π bonding electron pair associated with a C? C bond of the cyclopropane ring and (b) is via the typical‐π bonding of electron pair of the C?C bond of MECP. These two types of weak interactions are compared based on the calculated geometries, interaction energies, frequency changes, and topological properties of electron density. The integration of electron density over the interatomic surface is found to be a good measure for the strength of weak interaction. Furthermore, the total electron density and separated σ and π electron densities are also computed and discussed in this article. The separated electron density shows σ electron density determined the strength and π electron density influenced the direction of the hydrogen/halogen bond. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Properties of copper (fluoro-)phthalocyanine layers deposited on epitaxial graphene

We investigate the atomic structure and electronic properties of monolayers of copper phthalocyanines (CuPc) deposited on epitaxial graphene substrate. We focus in particular on hexadecafluorophthalocyanine (F(16)CuPc), using both theoretical and experimental (scanning tunneling microscopy - STM) studies. For the individual CuPc and F(16)CuPc molecules, we calculated the electronic and optical properties using density functional theory (DFT) and time-dependent DFT and found a red-shift in the absorption peaks of F(16)CuPc relative to those of CuPc. In F(16)CuPc, the electronic wavefunctions are more polarized toward the electronegative fluorine atoms and away from the Cu atom at the center of the molecule. When adsorbed on graphene, the molecules lie flat and form closely packed patterns: F(16)CuPc forms a hexagonal pattern with two well-ordered alternating α and β stripes while CuPc arranges into a square lattice. The competition between molecule-substrate and intermolecular van der Waals interactions plays a crucial role in establishing the molecular patterns leading to tunable electron transfer from graphene to the molecules. This transfer is controlled by the layer thickness of, or the applied voltage on, epitaxial graphene resulting in selective F(16)CuPc adsorption, as observed in STM experiments. In addition, phthalocyanine adsorption modifies the electronic structure of the underlying graphene substrate introducing intensity smoothing in the range of 2-3 eV below the Dirac point (E(D)) and a small peak in the density of states at ～0.4 eV above E(D).     

Synthesis, structures, and reactivity of yttrium alkyl and alkynyl complexes with mixed Tp(Me2)/Cp ligands

The structurally characterized Tp(Me2)-supported rare earth metal monoalkyl complex (Tp(Me2))CpYCH(2)Ph(THF) (1) was synthesized via the salt-metathesis reaction of (Tp(Me2))CpYCl(THF) with KCH(2)Ph in THF at room temperature. Treatment of 1 with 1 equiv of PhC≡CH under the same conditions afforded the corresponding alkynyl complex (Tp(Me2))CpYC≡CPh(THF) (2). Complex 1 exhibits high activity toward carbodiimides, isocyanate, isothiocyanate, and CS(2); treatment of 1 with such substrates led to the formation of a series of the corresponding Y-C(benzyl) σ-bond insertion products (Tp(Me2))CpY[(RN)(2)CCH(2)Ph] (R = (i)Pr(3a), Cy(3b), 2,6-(i)Pr-C(6)H(3)(3c)), (Tp(Me2))CpY[SC(CH(2)Ph)NPh] (4), (Tp(Me2))CpY[OC(CH(2)Ph)NPh] (5), and (Tp(Me2))CpY(S(2)CCH(2)Ph) (6) in 40-70% isolated yields. Carbodiimides and isothiocyanate can also insert into the Y-C(alkynyl) σ bond of 2 to yield complexes (Tp(Me2))CpY[(RN)(2)CC≡CPh] (R = (i)Pr(7a), Cy(7b)) and (Tp(Me2))CpY[SC(C≡CPh)NPh] (9). Further investigation results indicated that 1 can effectively catalyze the cross-coupling reactions of phenylacetylene with carbodiimides. However, treatment of o-allylaniline with a catalytic amount of 1 gave only the benzyl abstraction product (Tp(Me2))CpY(NHC(6)H(4)CH(2)CH═CH(2)-o)(THF) (10), without observation of the expected organic hydroamination/cyclization product. All of these new complexes were characterized by elemental analysis and spectroscopic properties, and their solid-state structures were also confirmed by single-crystal X-ray diffraction analysis.     

Active cobalt catalyst for the cleavage of benzyl ether

An improved method for the deprotection of benzyl ethers using a catalytic amount of Co(2)(CO)(8) in the presence of Me(2)PhSiH and CO (1 atm) is described. The deprotection reaction is compatible with double bond or sulfur-containing substrates. The method also tolerates other functional groups, such as Ac, Piv, and Bz, and shows potential selectivity in perbenzylated monosaccharides.     

BF3·OEt2-promoted diastereoselective diacetoxylation of alkenes by PhI(OAc)2

Selective syn and anti diacetoxylations of alkenes have been achieved using a PhI(OAc)(2)/BF(3)·OEt(2) system in the presence and absence of water, respectively. A broad range of substrates including electron-deficient alkenes (such as α,β-unsaturated esters) could be elaborated efficiently at room temperature with this methodology, furnishing the desired products in good to excellent yields and diastereoselectivity. In particular, a multigram-scale diastereoselective diacetoxylation of methyl cinnamate (5.00 g) was also accomplished in a few hours, maintaining the same efficiency as small-scale reaction. This novel methodology provides an alternative approach for the preparation of various 1,2-diols.     

Femtosecond dynamics of the ring closing process of diarylethene: a case study of electrocyclic reactions in photochromic single crystals

The cyclization reaction of the photochromic diarylethene derivative 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene was studied in its single crystal phase with femtosecond transient absorption spectroscopy. The transient absorption measurements were performed with a robust acquisition scheme that explicitly exploits the photoreversibility of the molecular system and monitors the reversibility conditions. The crystalline system demonstrated 3 × 10(4) repeatable cycles before significant degradation was observed. Immediately following photoexcitation, the excited state absorption associated with the open-ring conformation undergoes a large spectral shift with a time constant of approximately 200 fs. Following this evolution on the excited state potential energy surface, the ring closure occurs with a time constant of 5.3 ps, which is significantly slower than previously reported measurements for similar derivatives in the solution phase. Time resolved electron diffraction studies were used to further demonstrate the assignment of the transient absorption dynamics to the ring closing reaction. The mechanistic details of the ring closing are discussed in the context of prior computational work along with a vibrational mode analysis using density functional theory to give some insight into the primary motions involved in the ring closing reaction.