Smectic I mesophase

Note 3 The in-plane positional correlations in a smectic I mesophase are slightly greater than in a smectic F mesophase. 

Note 4 Chiral materials form chiral smectic I mesophases denoted by SmI. ... 

Note There are three types of hexatic smectic mesophases. smectic B (SmB), smectic F (SmF) and smectic I (SmI). Here, the term hexatic may be omitted because it is implicit for this group of smectic mesophases. 

Note 3 By contrast with a smectic B mesophase, a crystal B mesophase has correlations of positional order (hexagonal) in three dimensions, i.e., correlations of position occur within and between layers. 

Note 1 See Figs. 9(a) and (b) for illustrations of the molecular organizations of smectic F and I mesophases. They are tilted analogues of the smectic B mesophase. 

Example The following compound exhibits a crystalline phase (Cr), smectic SmC, cubic (Cub), smectic SmA mesophases, and an isotropic (I) phase, with transitions at the specified temperatures ... 

The complexes bearing one chiral substituent display a smectic A mesophase when the non-chiral chain is long, or an enantiotropic cholesteric and a monotropic SmA phase for shorter alkoxy chains. A TGBA phase is observed for the derivative which contains the chiral isocyanide combined with the diethyloxy, when the SmA to cholesteric transition is studied. The compound with two chiral ligands shows a monotropic chiral nematic transition. When this compound is cooled very slowly from the isotropic liquid it exhibits blue phases BP-III, BP-II, and BP-I. 

Research utilizing the thiepine skeleton in material science has been reported. For example, liquid crystals with chiral dihydrodibenzo[c,i ]thiepines were studied. The enantiomerically pure (-)-(i )-3,9-bis[4-(dodecyloxy)benzoyl-oxy]-5,7-dihydro-l,l l-dimethyldibenzoR,f]thiepine 80 and (—)-(R)-3,9-bis[4-(dodecyloxy)benzoyloxy]-5,7-dihydro-1,1 l-dimethyldibenzoR,f]thiepine dioxide 82 display smectic C mesophases by a rigid twisted biphenyl core and axial chirality <1998JOC3895>. 

Whereas monophilic liquid crystals can show a high diversity of smectic phases (SmA-SmQ), the amphotropic liquid crystals normally exhibit only the SmA phase. Tilted smectic phases are only observed in a few cases. The first indication of possibly tilted phases was given in 1933 for thallium stearate [ 170]. A disordered SmC phase was also clearly deseribed for mesogens containing a classical calamitic core aside to their amphiphilic structure [171]. Monophilic liquid crystals can show various ordered tilted smectic phases, for example, smectic I, F, G, J, H, and K. In the case of lipids only one mesophase, the j8 phase,... 

The precursor 6 exhibits the enantiotropic nature of chiral nematic (N ), chiral smectic C (SmC ) and chiral smectic I (SmI ) phases. The shell-printed texture of the SmC phase and the rose-like texture of the SmI phase can be clearly seen in Figure 12.6. The thiophene monomers, M2 and M3, show enantiotropic N, SmA and SmC phases. The SmC phase is characteristic of ferroelectricity. The polymers show various mesophases. The phase transition temperatures are summarized in Table 12.4. PI shows an enantiotropic SmA phase. P2 shows enantiotropic SmA, SmC and SmB phases. The fan-shaped texture of the SmA phase and the striated fan-shaped texture of the SmC phase are shown in Figure 12.7. P3 shows an SmA phase in the heating process and SmA and SmX phases in the cooling process. XRD analysis suggests that the SmX phase of P3 might be a higher order smectic phase. 

The sense of the pitch of the chiral smectic C mesophase is controlled by the same molecular factors as that of the cholesteric phase. If a chiral nematic forms a tilted smectic phase (C, H, I ) on cooling, either directly or through an intermediate smectic A phase, the smectic phase has the same sense of rotation as the chiral nematic phase. 

The wide angle X-ray diffraction pattern tom melt-drawn fiber of homopolyester, obtained from the reaction of l,3-bis(p-hydroxyphenyl)-l,3-propanedione and 4,4 -hexamethylenedioxy-dibenzoyl chloride, exhibits a typical smectic A mesophase, i. e., an inner reflection as spot at the meridional position and a diffuse outer reflection at the equatorial position (Figure 8.27). 

Monomers comprising norbomene and Choi moieties with or without alkyl spacers (Fig. 8f) have been synthesized and polymerized by ROMP using second generation Grubbs catalysts [208]. A smectic A mesophase is formed only when the spacer is long enough. The Chol-based ROMP monomer can also be copolymerized with two others, i.e., with a short PEG side chain and a crosslinking tmit, to create a shape memory polymer network [209], where the smectic A mesophase of Choi moieties plays an important role in the shape memory behavior. 

Benouazzane, M., Coco, S., EspineL P., Martm-Alvarez, J. and Barbera J. (2002) Liquid crystalline behavior in gold(I) and silver(I) ionic isocyanide complexes smectic and columnar mesophases. Journal of Materials Chemistry, 12, 691-696. 

Complexes with the simplest alkoxyphenylisocyanide and several halides are prepared by metathetical reactions of [AuCl(CNR)] with KX salts (Figure 7.19) [17]. The chloro-derivatives (n > 4) andthebromo-complexes (n > 6) display SmA phases. However, the ligands and the iodo-complexes are not liquid crystals. The transition temperatures decrease in the order Cl > Br > I, according to the decrease in polarity of the Au—X bond. It is important to note that the coordination of a very simple non-mesomorphic isocyanide (only one alkoxy chain and one aromatic ring) to Au—Cl allows the formation of a quite ordered and stable smectic mesophase. 

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