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A unique morphology for bent-core liquid crystals forming the B4 phase has been found for a class of tris-biphenyl bent-core liquid crystal molecules with a single chiral side chain in the longer para-side of the molecule. Unlike the parent molecules with two chiral side chains or a chiral side chain in the shorter meta-side, which form helical nano- or microfilament B4 phases, the two derivatives described here form heliconical-layered nanocylinders composed of up to 10 coaxial heliconical layers, which can split or merge, braid, and self-assemble into a variety of modes including feather- or herringbone-type structures, concentric rings, or hollow nest-like superstructures. These multi-level hierarchical self-assembled structures, rivaling muscle fibers, display blue structural color and show immense structural and morphological complexity.

The effect of the molecular chirality of chiral additives on the nanostructure of the twist-bend nematic (NTB) liquid crystal phase with ambidextrous chirality and nanoscale pitch due to spontaneous symmetry breaking is studied. It is found that the ambidextrous nanoscale pitch of the NTB phase increases by 50% due to 3% chiral additive, and the chiral transfer among the biphenyl groups disappears in the NTB* phase. Most significantly, a twist-grain boundary (TGB) type phase is found at c > 1.5 wt% chiral additive concentrations below the usual N* phase and above the non-CD active NTB* phase. In such a TGB type phase, the adjacent blocks of pseudo-layers of the nanoscale pitch rotate across the grain boundaries.

We show a possibility of the spectrophotometric determination of 2,4-dichlorophenoxyacetic acid based on the extraction of its ion pair (IP) with polymethine dye Astrafloxin FF with toluene. The maximum recovery of the ion pair from the aqueous phase is achieved at pH 6-11 and a dye concentration of (1.6-2.8) x 10.sup.-4 M. The conditional molar absorption coefficient of the ion pair is 4.0 x 10.sup.4, and the limit of detection for 2,4-dichlorophenoxyacetic acid is 0.9 [micro]g/mL. The developed method of the extraction-spectrophotometric determination of 2,4-dichlorophenoxyacetic acid was used to analyze water and herbicides., Author(s): Zh. A. Kormosh [sup.1], E. S. Zhurba [sup.1], I. P. Antal [sup.1], A. Zh. Kormosh [sup.1], Ya. R. Bazel [sup.2] [sup.3] Author Affiliations: (1) grid.448950.4, 0000 0004 0399 8646, [...]

Sensors for the potentiometric determination of mefenamic and phenylanthranylic acids are prepared on the basis of single- and the double-layer plasticized polyvinylchloride membranes. Ion pairs of perchlorate and mefenamic and phenylanthranylic acid with basic fuchsin are synthesized for the fabrication of membranes. The composition of compounds is confirmed by spectrophotometry and IR spectrometry. Effects of different factors on the electrode characteristics are studied, the composition of the membranes is optimized. The proposed procedure for the fabrication of double-layer membranes ensures the improvement of the properties of sensors for mefenamic and phenylanthranylic acids. The developed procedures are applied to the analysis of pharmaceutical preparations., Author(s): Zh. A. Kormosh [sup.1], O. Yu. Matviichuk [sup.1], I. P. Antal [sup.1], Ya. R. Bazel' [sup.2] [sup.3] Author Affiliations: (1) grid.448950.4, 0000 0004 0399 8646, Chemistry Department, Lesya Ukrainka [...]

Following the principle of the enzyme-linked immunosorbent assay (ELISA) pathogen detection method, we demonstrate specific sensing of goat Immunoglobulin G (IgG) by a nematic liquid crystal material. Sensing occurs via the visually-striking realignment of a pre-fabricated liquid crystal film, suspended in grids and coated with biotinylated lipids followed by biotinylated anti-goat IgG. Realignment occurs when the targeted goat IgG is added to the cell, but not when rat or rabbit serum IgG is added to the same surface. In principle, this method can be generalized to provide an inexpensive, fast and sensitive prefabricated sensor for any pathogen. Keywords: Liquid crystal, Specific sensing, Optical biosensor