P-120: Low Voltage FLC for Fast Active Matrix Displays

The process of FLC director reorientation in alternating electric field is considered for the case when interaction of FLC molecules with the substrates results in partial unwinding the helix structure and motion of domain walls. The hysteresis-free electrooptical response as fast as 50…70 μs was achieved in the FLC cell of 1.3-μm thickness in the electric field 1 V/μm. This result is very important for the practical use of FLC in fast active matrix displays

In-plane Switching Deformed Helix Ferroelectric Liquid Crystal Display Cells

In-plane electro-optical switching (IPS) is a natural feature of a conventional planar-aligned display cell based on the deformed helix ferroelectric liquid crystal effect (DHFLC-effect) with a sub-wavelength helix pitch, if the tilt angle is close to 40 degrees

Well-Known Mediators of Selective Oxidation with Unknown Electronic Structure: Metal-Free Generation and EPR Study of Imide‑<i>N</i>‑oxyl Radicals

Nitroxyl radicals are widely used in chemistry, materials sciences, and biology. Imide-<i>N</i>-oxyl radicals are subclass of unique nitroxyl radicals that proved to be useful catalysts and mediators of selective oxidation and CH-functionalization. An efficient metal-free method was developed for the generation of imide-<i>N</i>-oxyl radicals from <i>N</i>-hydroxyimides at room temperature by the reaction with (diacetoxyiodo)­benzene. The method allows for the production of high concentrations of free radicals and provides high resolution of their EPR spectra exhibiting the superhyperfine structure from benzene ring protons distant from the radical center. An analysis of the spectra shows that, regardless of the electronic effects of the substituents in the benzene ring, the superhyperfine coupling constant of an unpaired electron with the distant protons at positions 4 and 5 of the aromatic system is substantially greater than that with the protons at positions 3 and 6 that are closer to the <i>N</i>-oxyl radical center. This is indicative of an unusual character of the spin density distribution of the unpaired electron in substituted phthalimide-<i>N</i>-oxyl radicals. Understanding of the nature of the electron density distribution in imide-<i>N</i>-oxyl radicals may be useful for the development of commercial mediators of oxidation based on <i>N</i>-hydroxyimides