First observation of aS C * -S A-TGBA multicritical point in a pure compound

High pressure experiments have been performed by thermobarometric analysis on two homologous (n=10 and 11) of the [3-fluoro-4((R) or (S)-methylheptyloxy) 4′-(4″-alkoxy-3″-fluorobenzoyloxy) tolans series, which both exhibit the TΓB_A phase. The character (first or/and second order) of the transitions involving the TGB_A phase are determined from thermobarograms. The pressure-temperature phase diagrams show that the TGB_A phase is stabilized under high pressure for the two compounds. Forn=11 an inducedS _A phase is observed under high pressures leading to the first experimental observation, on pressure-temperature phase diagram of pure compounds, of aS _C ^* -S _A-TGB_A multicritical point, previously predicted by the Renn-Lubensky theory.     

High pressure studies on new chiral compounds exhibiting TGBA phase

Effects of high pressures on phase sequences of the two homologousn=16 andn=18 of the (3-fluoro-4 ((R) or (S)-methylheptyloxy) 4, (4-fluoro benzoyloxy) tolans) series have been studied. Both compounds exhibit the new twisted Smectic A phase called Twist Grain Boundary TGB_A phase. The high pressure experiments were performed by thermobarometric analysis. The order of the transitions (first or second) have been determined in respect to pressure and temperature. The pressure-temperature phase diagrams show that the TGB_A phase is stabilized by increasing pressure; an inducedN ^* phase appears under high pressure for n=18 leading to the observation of TGB_A-N ^*-I triple point.     

Pressure effect on the nematic-isotropic transition in dilaterally substituted nematogens

The effect of pressure on the liquid crystal properties of two new dilaterally substituted nematogens has been studied. The method employed involves measurement of the thermal pressure variation of a sample under isochoric conditions. The pressure-temperature phase diagrams were determined. As for unsubstituted compounds, the nematic phase is stabilized upon application of pressure. The values of the (?T/?P)^NI slopes of the clearing lines for these nematogens are, however, significantly higher than those generally characterizing rod-shaped nematics. The entropy separation method was used to estimate the constant volume and the volume-dependent terms of the entropy changes at the nematic-isotropic transition. The values of these contributions were determined on the basis of thermobarometric data showing that the transition entropy is strongly volume-dependent. This suggests that the higher values of the (?T/?P)^NI slopes observed for these compounds can be related to the rearrangement of the lateral flexible chains in the nematic phase when the pressure increases, leading to a decrease of the excluded free volume caused by the bulky core of the molecules.     

Impact of Geometric Parameters,Charge, and Lipophilicity on Bioactivity of Armed Quinoxaline,Benzothiaole, and Benzothiazine: Pom Analyses of Antibacterial and Antifungal Activity

Abstract

A series of four different armed heterocyclic candidates; 1-(2-methyl-2,3-dihydro-1,3-benzothiazol-2-yl)acetone (2), 1-(3-methyl-4H-1,4-benzothiazin-2-yl)ethanone (3), 2-[(2-aminophenyl)dithio]aniline (4), and 3-hydroxy-3-methyl-4-(3-methyl-2-quinoxalinyl)-2-butanone (5) have been prepared and their microbial activities were evaluated. A correlation of the structure and activities relationships of these compounds with respect to molecular modeling, Lipinski Rule of Five, drug likeness, toxicity profiles, and other physico-chemical properties of drugs are described and verified experimentally.