Syntheses of new unsymmetrically dodecakis(trifluoroethoxy)‐substituted metallophthalocyanines by a palladium‐catalyzed cross‐coupling reaction

Novel unsymmetrical vanadyl and zinc dodecakis(2,2,2‐trifluoroethoxy)phthalocyaninates with an iodo group were synthesized by a statistical condensation route. The palladium‐catalyzed coupling reaction between such monoiodinated metallophthalocyanines and terminal acetylenic derivatives gave various new unsymmetrically dodecakis(2,2,2‐trifluoroethoxy)‐substituted metallophthalocyanines with extended exocyclic π‐conjugation. Unsymmetrical zinc dodecakis(2,2,2‐trifluoroethoxy)phthalocyaninate with a nitro group was also prepared for comparison. All the target phthalocyanines were separated by common col umn chromatography and characterized by elemental analysis, ir and ¹H‐nmr, uv‐visible and fast‐atombombardment mass spectroscopy.     

The analysis of radiolysis impurities in <Superscript>18</Superscript>F-FDG and methods of repurification

To investigate the radio impurity in the radiolysis of ¹⁸F-FDG at high radiodose and radioconcentrated solutions and develop methods of repurification. The radiolysis of ¹⁸F-FDG was analyzed by TLC. The radio-impurity was confirmed by biodistribution and small animal PET/CT studies. ¹⁸F-FDG was unstable at high radioconcentrition over 37 GBq/mL or under basic condition. TLC, biodistribution and PET/CT all indicated that the main autoradiolysis byproduct was free fluoride ion. The radiolyzed ¹⁸F-FDG was repurified by solid-phase extraction (SPE) column. The repurified ¹⁸F-FDG had a radiochemical purity (RCP) of over 99% and significantly lower bone uptake than that was before repurification (P = 0.0003). There was a positive correlation between the recovery yield and the purity of ¹⁸F-FDG (R ² = 0.66).     

Synthesis of 14-Bromo and 14-Hydroxy Baccatin III Derviatives

Numerous efforts towards synthesis of anticancer drug paclitaxel (Taxol(r), 1a) with improved activities led to the modification at 13-phenylisoserine side chain and different positions of its core structure-baccatin III 1c1. At the same time, the activities of searching new taxoids for starting materials of new semi-synthetic paclitaxel analogs from Taxus spp. plant have not ever been stopped. Among these taxoids, 14?-hydroxy-10-deacetylbaccatin III 22 and 13-acetyl-9-dihydrobaccatin III …     

Crystallographic report: Bis[tris(2‐methyl‐2‐phenylpropyl)tin] piperazinyldithiocarbamate

The centrosymmetric structure of bis[tris(2‐methyl‐2‐phenylpropyl)tin]piperazinyldithiocarbamate contains four‐coordinated tin and monodentate dithiocarbamate ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

Nonexistence of axially symmetric,stationary solution of Einstein Vacuum Equation with disconnected symmetric event horizon

In this short note, we prove that if an axially symmetric, asymptotically flat, stationary solution of the Einstein Vacuum Equation admits an involution interchanging the components of the event horizons, then the force between at least two of the event horizons must be positive. The proof is based on an observation that in this case the force can be expressed as a line integral with positive integrand.     

Effect of Mn-site vacancies on the magnetic entropy change and the Curie temperature of La0.67Ca0.33Mn1−xO3 perovskite

Single-phase polycrystalline samples of La_0.67Ca_0.33Mn_1−xO₃ (x=0.00, 0.02, 0.04, 0.06) have been prepared using the sol-gel method. The structure, magnetocaloric properties and the Curie temperature of the samples with different Mn vacancy concentrations have been investigated. The experimental results show that vacancy doping at the Mn-sites has a significant influence on the magnetic properties of La_0.67Ca_0.33Mn_1−xO₃. The Curie temperature decreases monotonically with increasing the Mn-site vacancy concentration x. A remarkable enhancement of the magnetic entropy change has been obtained in the La_0.67Ca_0.33Mn_0.98O₃ sample. The entropy change reaches |ΔS_M|=3.10 J kg⁻¹ K⁻¹ at its Curie temperature (264 K) under an applied magnetic field H=10 kOe, which is almost the same value as that of pure Gd.     

Synthesis and two‐photon absorption properties of hyperbranched diketo‐pyrrolo‐pyrrole polymer with triphenylamine as the core

A novel hyperbranched polyyne (hb‐ DPP ) with triphenylamine as the core, 2,5‐dioctylpyrrolo [3,4‐c]pyrrole‐1,4 (2H,5H)‐dione ( DPP ) as the connecting unit has been designed and synthesized by Glaser‐Hay oxidative coupling reaction, which was characterized by IR, NMR, UV‐vis, FL, and GPC. The polymer exhibits high molecular weight (M_w up to ～6.55 × 10⁴ Da) and is readily soluble in common organic solvents such as toluene, chloroform, tetrahydrofuran, N,N‐dimethyl formamide and so on. The one‐ and two‐photon absorption (TPA) properties have been investigated. The TPA cross section of the polymer was measured by open‐aperture Z‐scan experiment using 140 femtosecond (fs) pulse, and the TPA cross section for hb‐ DPP was determined to be 579 GM per repeating unit at wavelength of 800 nm. In tetrahydrofuran, hb‐ DPP exhibits intense frequency up‐converted fluorescence with the peak located at 584 nm under the excitation of 800 nm fs pulses. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4400–4408, 2009     

Structural stability of heat-treated CoN/CN soft X-ray multilayers fabricated by dual-facing-target sputtering

286 , 176 (1996)]. (1) The interdiffusion critical wavelengths were calculated as 2.00–2.04 nm at temperatures ranging from 473 to 523 K, which is equal to those of Co/C multilayers within the experimental error, indicating that the interdiffusion behaviours in the CoN/CN multilayers are still decided by the thermodynamic properties of the Co-C system. (2) The effective interdiffusivities and macroscopic diffusion coefficients are smaller. (3) The activation energy for diffusion is larger. The features imply that it is possible to improve the thermal stability of Co/C multilayers by doping with N atoms. The high-temperature annealing results imply that the destructive threshold of the CoN/CN multilayers is 100–200 °C higher than that of Co/C multilayers. The small-angle X-ray diffraction of CoN/CN soft X-ray multilayers indicates that the period expansion of the multilayers is only 4% at 400 °C, and the interface pattern still exists even if they were annealed at 700 °C. The large-angle X-ray diffraction and transmission electron microscopy analysis reveal that the crystalline process is significantly retarded if doped with N atoms, leading to a smaller grain size at higher annealing temperatures. The significant improvement of the thermal stability can be interpreted with Raman spectroscopy and X-ray photoelectron spectroscopy analysis. The Raman spectra give the evidence that the formation of the sp³ bonding in the CN sublayers can be suppressed effectively by doping with N atoms, and thus the period expansion resulting from the changes in the density of CN layers can be decreased considerably. The X-ray photoelectron spectra give information about existence of the strong covalent bonding between N atoms and the ionic bonding between Co and N atoms, which can slow down the tendency of the structural relaxation. The interstitial N atoms decrease the mobility of Co atoms, and thus the fcc Co and hcp Co coexist even though the annealing temperature is much higher than the phase transformation temperature of 420 °C, leading to the suppression of the grain growth. Received: 29 May 1997/Accepted: 8 September 1997