Structures and absolute stereochemistry of (-)-echitoveniline, (-)-11-methoxyechitoveniline and (-)-11-methoxyechitovenedine—new indole alkaloids of

Structures and absolute stereochemistry of (-)-echitoveniline, (-)-11-methoxyechitoveniline and (-)-11-methoxyechitovenedine, three new indole alkaloids of the vincadifformine type, isolated from the fruits and leaves of Alstonia venenata R.Br., have been established as 3b, 3c and 3d, respectively, on the basis of spectral and chemical evidence. A plausible mechanism of the LAH reduction of the δ-lactones8b and8c to the corresponding diols 9b and 9c has been discussed.     

Strong reduction of optimum pump power for efficient wave conversion in optical fibers with dual-frequency circularly polarized pump waves

We present experiments that show achievement of highly efficient generation of parametric sidebands in an optical fiber with dual-frequency, circularly polarized pump waves. An appropriate choice of the separation between the pump frequencies permits a strong reduction of the optimum power for highly efficient frequency conversion.     

Analytical method for designing dispersion-managed fiber systems

Using the equations of motion of pulse width and chirp, we present an analytical method for designing dispersion-managed (DM) fiber systems without optical losses. We show that the initial Gaussian pulse considered for the analytical design of periodically amplified DM fiber systems with losses will propagate as a proximity fixed point. Then averaging the DM soliton fields obtained from the slow dynamics of the proximity fixed point will yield the exact fixed point.     

Linked photoswitches where both photochromes open and close

In the dithienylethene photochrome series, linking two photochromes together directly, or with an ethynyl spacer, shuts down the photoswitching of one of the photochromes. We report here, that for dihydropyrenes, two photochromes can be linked together without affecting the ability of either to photoswitch. [reaction--see text]     

Three‐dimensional networks containing rectangular Sr4 and Ba4 units: Synthesis,structure, bonding,and potential application for Ne gas separation

New porous three‐dimensional metal‐organic frameworks are synthesized that contain infinite chains of Sr_n and Ba_n rectangles. Their structures are elucidated by means of spectroscopic techniques such as nuclear magnetic resonance and Fourier transform infrared, and the respective crystal structures are determined. The electronic structure of basic units of the crystals are computed using density functional theory at the B3LYP/6‐31G(d,p)/def2‐TZVP level, and the bonding and reactivity are analyzed using natural bond orbital analysis, the quantum theory of atoms in molecules, and conceptual density functional theory. The possibilities of noble gas (Ng) storage inside the crystal structures are explored through modeling a Ng atom inside the frozen geometry of the crystal. It was found that a neon atom can fit into a cavity in the Sr and Ba crystal structures whereas other Ngs (He, Ar, Kr) exhibit repulsive interactions with the crystal structure. Ab initio molecular dynamics simulations for up to 500 fs at 77 and 298 K suggest that the structures incorporating a neon atom are kinetically stable. © 2015 Wiley Periodicals, Inc.     

ChemInform Abstract: Noble Gas Supported B3+ Cluster: Formation of Strong Covalent Noble Gas—Boron Bonds.

B₃Ng₃⁺ (Ng: He—Rn) complexes are characterized by quantum chemical MP2 and CCSD(T) calculations.     

Preparation and preliminary bioevaluation of 68Ga-oxine in lipiodol as a potential liver imaging agent

Lipiodol functions as an embolizing agent for trans-arterial embolization and is used to deliver localized doses of chemotherapeutic drugs as well as ionizing radiation to cancerous tissue of the liver. Therefore, an attempt was made to prepare ⁶⁸Ga-labeled lipiodol, which may have potential as a PET radiotracer for imaging of liver cancer. ⁶⁸Ga-labeled lipiodol was prepared by a two-step procedure involving formation of highly lipophilic ⁶⁸Ga-oxine complex followed by its dispersion in lipiodol. Preliminary biological evaluation in normal Wistar rats revealed satisfactory hepatic retention with insignificant uptake in any other major organ/tissue indicating promising potential of the agent.