Nonlinear optical thin film device from a chiral octopolar phenylacetylene liquid crystal.

A set of chiral discotic phenylacetylenes have been synthesized by 3-fold Sonogashira coupling between different ethynylbenzenes and triiodobenzenes. The resultant bulk materials are fully characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction. The octopolar nature of the target compounds is studied by UV-vis absorption spectroscopy and hyper-Raleigh scattering in solution.

Steric and electronic situation in the 4-X-4'-[(4''-Y-phenyl)ethynyl]biphenyl homologous series: a joint theoretical and spectroscopic study.

In this work we have studied the rotational barriers, the polarization of the acetylenic triple bond, and the molecular dipole moments in the 4-X-4'-[(4''-Y-phenyl)ethynyl]biphenyl homologous series using the density functional theory (DFT) and 1D/2D NMR spectroscopy. This series of compounds constitutes an effective base for the acquisition of liquid crystals. The equilibrium angle (theta(eq)) and the torsional barriers DeltaE(0 degrees) and DeltaE(90 degrees) are not very sensitive to the substituent effects.