Ferroelectric liquid crystals (FLCs) are being investigated as alternatives to nematic liquid crystals in display applications due to their low power requirements and fast switching times. Commercial FLCs consist of a chiral dopant in an achiral smectic C (SmC) liquid crystal host. A bulk property that arises from the chiral nature of this mixture is a spontaneous polarization (PS), which depends on the polarization power of the chiral dopant (δp). The magnitude of δp reflects the ability of a dopant to induce a polarization in an achiral host. It has been proposed that the magnitude of δp can be enhanced by matching dopant and host structures, which may enhance the propagation of chiral perturbations from the dopant to the host. This is known as the chirality transfer feedback (CTF) model. Previous studies in the Lemieux lab featured 2H NMR to detect chiral perturbations exerted by a dopant on the liquid crystal host based on the observation of pairs of quadrupolar doublets in the 2H NMR spectra. In the work described herein, the contribution of chirality transfer feedback to the difference in quadrupolar splitting between pairs of quadrupolar doublets (ΔΔνQ) was assessed by 2H NMR spectroscopy. These experiments confirmed the results reported by Finden and Yuh by demonstrating the presence of chiral perturbations exerted by a diester substituted 6,6’-spirobiindandione dopant ((RS)-2.6-d4) on the achiral SmC host NCB76, and the absence of those perturbations using the diester substituted 5,5’-spirobiindandione analogue ((RS)-2.3-d4). Subsequent studies explored the effect of modifying the chiral topography of the 2,2’-spirobiindan-1,1’-dione core on the magnitude of δp. Both the 5,5’- and 6,6’-disubstituted cores were reduced to give the corresponding mono-carbonyl derivatives ((R)-3.4-d4 and (R)-3.8-d4), substituted with ether side-chains. Finally, ester side-chains were added to the 6,6’- mono-carbonyl derivative ((R)-3.9-d4) for comparison with previous experiments. The ferroelectric induction properties of these dopants were investigated in NCB76 at mole fractions ranging from xd = 0.03 – 0.10. The mono-carbonyl 5,5’- and 6,6’-diether dopants gave absolute polarization powers of 120 nC/cm2 and 123 nC/cm2 respectively, which are not significantly different. This suggests that a reduction in the chiral topography of the spirobiindandione core greatly affects the polarization power of the dopant and may reduce the contribution from chirality transfer to δp. This was confirmed by a measurement of the polarization power of the 6,6’-diester mono-carbonyl dopant (R)-3.9-d4 in NCB76, which gave a δp value of 117 nC/cm2. / Thesis (Master, Chemistry) -- Queen's University, 2008-07-11 15:10:53.56

A series of phenanthrene and oxidized phenanthrene derivatives with typical substitution patterns, 1.31, 1.32, 2.30a-f, 3.1a,b and (-)-4.1 have been synthesized as liquid crystal cores by a combined Directed ortho Metalation (DoM), cross coupling and Directed Remote Metalation (DreM) strategy. The synthetic methodology employed allowed variation of the tail and core structures, for the preparation of a new smectic liquid crystal compound (1.32), a homologous series of 9,10-dihydrophenanthrene-9,10-diones (2.30a-f), a diastereomeric trans-9,10-dihydrophenanthrene-9,10-diol (1.31), two enantiomeric 9,10-dihydrophenanthrene-9,10-diones (R)-3.1a-b) and an enantiomeric 9,10-dihydro-9,10-dimethylphenanthrene-9,10-diol ((-)-4.1). Polarized microscopic and differential scanning calorimetric measurements suggest that 1.31 forms a large range of SmC phase, ca. 100 ºC, followed by a small range of nematic phase, ca. 10 ºC; the 2.30a-f series show similar mesogenic properties, but with the extension of the length of a side chain from six carbons to eleven carbons, the nematic phase has disappeared (in the cases of 2.30a-c). Although (R)-3.1a-b and (-)-4.1 are not liquid crystals, they show ferroelectric induction by doping, in the amount of ca. 5 mol%, into unchiral liquid crystal hosts PhB, DFT, PhP1, NCB76 and 2.30f. However, due to the detection limit of the instrument, i.e., ca. 0.5 nC/cm2, the spontaneous polarizations (Ps) induced could not be measured. / Thesis (Ph.D, Chemistry) -- Queen's University, 2009-08-17 15:52:54.612

Ferroelectric liquid crystals (FLCs) have been investigated as the basis for a new type of liquid crystal display because of their fast switching times. Commercial FLC materials are mixtures consisting of a small amount of chiral dopant in an achiral liquid crystal host with an isotropic-nematic-smectic A-smectic C (INAC) phase sequence, which is required to achieve proper alignment between glass slides with rubbed polyimide alignment layers. However, the layer contraction occurring at the SmA-SmC phase transition on cooling from isotropic liquid is a severe problem that leads to a buckling of the smectic layers and results in zigzag defects that drastically degrade the optical quality of FLC films. To solve this problem, we are focusing on a new class of liquid crystal molecules with minimal or no smectic layer shrinkage at the SmA-SmC transition which is referred to as ‘de Vries-like.’ Previous work in the Lemieux group has shown that combining structural elements promoting SmA and SmC phases in a single molecule increases de Vries-like behavior. Giesselmann et. al. suggest that a correlation exists between the temperature range of the SmA phase and de Vries-like behavior. In the study described herein, two homologous series of molecules with 2-phenylpyrimidine cores with siloxane-terminated side-chain (SmC promoting element) and a chloro-terminated side-chain (SmA promoting element)are synthesized and characterized by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction (SAXS). The reduction factor R for series 1.13 from 0.36 to 0.46 and for series 1.14 from 0.47 to 0.54. Results show that, although there is some correlation between % layer contraction and SmA temperature range, it can be explained primarily by differences in tilt angle θ. When θ is taken into account in the R values, there is no correlation. Another aspect of the study described herein, two siloxane-terminated 2-phenylpyrimidine chiral dopants are synthesized and characterized by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction (SAXS). / Thesis (Master, Chemistry) -- Queen's University, 2009-11-30 13:42:44.584

Work on developing an instrumental system for total analysis of triglycerides and phospholipids is presented. Initial chromatographic analysis using reversed-phase high performance liquid chromatography on C(,6)-bonded, 5 (mu)m silica stationary phase and acetonitrile-water (and dilute phosphoric acid with phospholipids) mobile phase is demonstrated. The Kovats index is shown to allow correlation of structure to retention behavior. An ultraviolet absorbance detector ((lamda)(,195m,)) and novel post-column reaction detector (p.c.r.) based on saponification, periodate oxidation and derivatization using a new class of reagents are used for detection. The p.c.r. is shown to be sensitive to samples in the lower nanomole-per-injection range. / A novel transport-thermal ionic detector for organophosphorus compounds and a new class of aldehyde reagents are introduced. The detector is capable of detecting some pesticides in the lower nanogram-per-injection range. The aldehyde reagents, called the Fluorals, of which Fluoral-P (4-amino-3-penten-2-one) is studied extensively, have promise of being useful for selective, rapid and sensitive (sub-nanomoles formaldehyde) determinations.

.. Detailed experimental and thermodynamic studies of. the isothermal phase equilibria for the / Thesis (Ph.D.)-University of Natal, 1990.

Studies of liquid crystal (LC) /Au nanoparticle (NP) composites have been pursued in columnar and in nematic phases of thermotropic LCs. Using LCs forming a columnar phase, we found that different functionalities on the corona of the Au NPs (hydrophobic vs. hydrophilic) display unique effects on the stability and ordering of the columnar LC phase. Doping nematic LCs with non-chiral or chiral Au NPs causes the formation of textures commonly observed for chiral nematic LCs, i.e., the formation of somewhat uniform stripe textures or patterns separated by areas of homeotropic alignment of LC molecules. Two scenarios are proposed. In the first scenario, the Au NPs form topological chain-like defects and the remaining Au NPs reside at the interface inducing vertical alignment of the LC molecules. In the second scenario, chiral Au NPs transfer chirality to the nematic LC host. Further, induced circular dichroism studies proved the second scenario. Using the same chiral Au NP systems, the origin of chirality of Au NPs has also been studied, and a powerful methodology has been proposed to unravel the puzzle of chirality of chiral ligand-protected Au NPs. Further investigations of these texture phenomena led to the discovery of using metal NPs to control the orientation and alignment of LCs. In due course, a dual alignment and electro-optical switching behaviour was found using alkylthiol-capped Au NPs doped into a nematic LC with positive dielectric anisotropy in planar namatic LC cells. This study was also expanded to Ag and CdTe NPs, which showed the same phenomenon, and all investigated NPs significantly reduced the voltage needed to re-orient the LCs in an electric field (threshold voltage). Starting from basic and moving on to more application-oriented research, we finally also initiated structure-property relationship studies of LC/NP composites.

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