A new general route to 1,2-diarylethylenes, 1,4-diarylbutadienes and 1,6-diarylhexatrienes through cycloaromatization of β-oxodithioacetals

A new general route for the title olefins 5a-e, 12, 13, 8a-e and 11a-e has been developed through nucleophilic addition of respective Grignard reagents i.e. allyl-, benzyl-, 1-(naphthylmethyl) magnesium halides to 5-aryl- 1,1-bis(methylthio)pent-4-en-3-ones, 7-aryl-1,1-bis(methylthio)hepta-4,6-dien-3-ones and 9-phenyl-1, 1-bis(methylthio)nona-4,6,8-trien-3-one followed by cycloaromatization of the resulting 3-substituted 1,1-bis(methylthio)alken-3-ols in the presence of boron trifluoride-diethyl ether complex

Facile synthesis of enantiopure chiral molecular rectangles exhibiting induced circular dichroism

The facile syntheses of enantiopure molecular rectangles using 1,8-bis(trans-Pt(Pet₃)₂(NO₃))anthracene and optically pure D- or L-tartrate are reported in high yields. These self-assembled macrocycles are unique examples where the phenomenon of Induced Chiral Dichroism (ICD) has been observed in chiral metallosupramolecular assemblies

Enhanced Thermoelectric Properties of Selenium-Deficient Layered TiSe_2–<i>x</i>: A Charge-Density-Wave Material

In the present work, we report on the investigation of low-temperature (300–5 K) thermoelectric properties of hot-pressed TiSe₂, a charge-density-wave (CDW) material. We demonstrate that, with increasing hot-pressing temperature, the density of TiSe₂ increases and becomes nonstoichiometric owing to the loss of selenium. X-ray diffraction, scanning electron microscopy, and transimission electron microscopy results show that the material consists of a layered microstructure with several defects. Increasing the hot-press temperature in nonstoichiometric TiSe₂ leads to a reduction of the resistivity and enhancement of the Seebeck coefficient in concomitent with suppression of CDW. Samples hot-pressed at 850 °C exhibited a minimum thermal conductivity (κ) of 1.5 W/m·K at 300 K that, in turn, resulted in a figure-of-merit (<i>ZT</i>) value of 0.14. This value is higher by 6 orders of magnitude compared to 1.49 × 10^–7 obtained for cold-pressed samples annealed at 850 °C. The enhancement of <i>ZT</i> in hot-pressed samples is attributed to (i) a reduced thermal conductivity owing to enhanced phonon scattering and (ii) improved power factor (α²σ)