Synthesis of 2,2'-dihydroxybisphenols and antiviral activity of some bisphenol derivatives

New diphenylmethane-type 2,2'-dihydroxybisphenols (5a-d) were prepared regioselectively in good yields. We evaluated the antiviral activity of some bisphenol derivatives synthesized by the plaque reduction assay. Most of the compounds showed significant antiviral activity and the 4,4'-dihydroxybisphenol derivative (10) showed higher activity than 2,2'-bisphenol derivatives. This compound had EC50 value of 1.8 microg/ml.     

Single‐Line EPR Spectra from Radicals Encapsulated in Aggregates of Amphiphilic Block Copolymers with Hydrophobic Dendritic Pendants in Water

Summary: A water‐insoluble organic 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical is solubilized in aqueous solutions of aggregates of amphiphilic block copolymers with hydrophobic dendritic pendants. The number (100–200) of DPPH molecules solubilized in an aggregate, which is evaluated from UV‐visible absorption spectra, is in agreement with that of the DPPH radicals determined from electron paramagnetic resonance (EPR) spectroscopy. The DPPH radicals are stably solubilized without decomposition in the polymer aggregates. The radicals exhibit a single‐line EPR absorption, which is narrowed by the interspin interaction, and indicates the assembly formation of DPPH radicals in polymer aggregates. These results suggest the effective utilization of the DPPH radical as a spin‐probe indicator in aqueous solutions.

When DPPH is solubilized in aqueous solutions of NaAMPS‐b‐G2(n3), the polymer solutions become purple colored, which is characteristic of the DPPH radical.     

Spectral Behavior and Photophysical Parameters of Dihydrophenanthro[9,10-e][1,2,4]Triazine Derivative Dyes in Sol–Gel and Methyl Methacrylate Polymer Matrices

Journal of Fluorescence - This paper deals with the optical and photophysical properties of dihydrophenanthro[9,10-e][1,2,4]triazine fluorescent dyes doped in Silicate based sol–gel and...     

Thermal properties of AlN–Ce:YAG composite ceramic phosphor for laser lighting

Optical Review - The AlN–Ce:YAG composite ceramic is an effective phosphor for high-power laser illumination. The thermal properties of an AlN–Ce:YAG composite phosphor were studied to...     

Nonlinear rheology for threadlike micelles of tetraethylammonium perfluorooctyl sulfonate

Nonlinear rheological features were investigated for an aqueous solution of tetraethylammonium perfluorooctyl sulfonate (C₈F₁₇SO₃ ^–N⁺(C₂H₅)₄; abbreviated as FOSTEA). In the solution (c=0.045 mol/l; 28.3 g/l), spherical micelles of FOSTEA were connected with each other to form threads of pearl-necklace shape. These threads were further organized into a transient network to exhibit linear relaxation characteristic of living polymers, single-mode terminal relaxation widely separated from faster relaxation processes. Nonlinear relaxation experiments against large step-strains γ(≤8) revealed that the terminal relaxation mode had a γ-insensitive relaxation time but its relaxation intensity exhibited significant damping (much stronger than that for entangled polymers). In contrast, the relaxation time and intensity for the fast relaxation modes first increased and then decreased with increasing γ. Under shear flow, the FOSTEA threads exhibited strong thinning of the viscosity. These nonlinear features of the FOSTEA threads were compared with those of other threadlike micelles, analyzed on the basis of an empirically introduced constitutive equation, and discussed in relation to strain/low-induced scission of the living threads. Received: 20 February 1998 Accepted: 30 July 1998     

Crystal‐to‐Crystal Synthesis of Helically Ordered Polymers of Trehalose by Topochemical Polymerization

The synthesis of crystalline helical polymers of trehalose via topochemical azide–alkyne cycloaddition (TAAC) of a trehalose‐based monomer is presented. An unsymmetrical trehalose derivative having azide and alkyne crystallizes in two different forms having almost similar packing. Upon heating, both the crystals undergo TAAC reaction to form crystalline polymers. Powder X‐ray diffraction (PXRD) studies revealed that the monomers in both the crystals polymerize in a crystal‐to‐crystal fashion; circular dichroism (CD) studies of the product crystals revealed that the formed polymer is helically ordered. This solvent‐free, catalyst‐free polymerization method that eliminates the tedious purification of the polymeric product exemplifies the advantage of topochemical polymerization reaction over traditional solution‐phase polymerization.     

Phase Matching Property of Cross Polarization Four Wave Mixing in BaTiO3 Crystal

Four wave mixing (FWM) is of considerable interest in generation of a phase conjugate beam with photorefractive crystals. The common methods of FWM are parallel polarization FWM and cross polarization FWM. In this paper, we analyze the phase matching property of the latter. First, we consider the phase matching condition, and derive equations representing the angler relationship of interacting beams. Then, we consider the phase mismatching which is caused by shift of the probe beam angle from the phase matching condition, and calculate the effect of the shift of this angle on the amount of phase mismatching. We also determine and closely examine the coupling constant.