Smectic F mesophase

Note 1 See Fig. 9a for an illustration of the molecular organization in a smectic F mesophase, a tilted analogue of the smectic B mesophase. 

Note 6 Chiral materials form chiral smectic F mesophases denoted by SmF. ... 

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

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 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. 

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>. 

In our own work, carried out under an extensive collaboration with Professor George Gray, F.R.S., and Drs David Lacey and Peter Gemmell of Hull University (UK), we have studied a number of nematic, cholesteric and smectic polymer mesophases with a view to exploiting their electro-optical properties. Some of the typical structures studied are given in Fig. 3. These are only a few of the structures now available and the reader is referred to ref. 14 for a more complete range of polysiloxane systems as well as to the recent reviews" which also cover the acrylate and methacrylate backbone systems. 

Lateral fluorination affords derivatives (Figure 7.22) which display smectic A or nematic mesophases (except the iodo-2-fluoro derivative). The melting points decrease in the order 3-F 3> > H > 2-F while the clearing points follow the trend... 

Calamitic phases are essentially defined as a set of mesophases that occur between the breakdown of the long-range periodic, translational ordering of the crystal and the loss of long range orientational order at the transition to the isotropic liquid. In this context six mesophases exist the nematic phase and five smectic phases labelled A, B, C, F and I. Other closely related soft crystal phases, in which the molecules have long-range periodic order but are themselves rotationally disordered, also exist in concert with liquid crystal phases. This second set of mesophases are labelled E, J, G, H, and K, and are essentially the crystal versions of the... 

F%. Z Schematic representation of various mesophases Nematic, smectic A and smectic C... 

Fig. 5.25 Dependence on length of the lat xil chain and rigid core, mesophases sequence formed by T-shaped bolapolyphiles with nonpolar (alkyl or semiperfluoroalkyl) lateral chains [9, 137, 138], Abbreviations SmA smectic A phase Col rectangular columnar phase Col g square columnar phase Col/ hexagonal columnar phase Lcarti, Lanifi, Lamg laminated phases with different ordta of the rodlike units Cub bicontinuous cubic phase, branched axial rod-bundles Col/ f hexagonal columnar phase formed by non-branched axial rod-boundles...

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,... 

Figure 26. (Bio)mesogenic order-disorder patterns rather than geometric anisotropies as general preconditions for the appearance of mesophases a) classical thermotropic cyanobiphenyl nematic [25 a, 51e] and thermotropically designed steroid hormone cholesteric [17 a, c, d, 26 f, 51 a, s, u] b) protein-j3-sheet simulative diacylhydrazine smectic [17 a, c, d, 26f, 511] c) hexaalkanoyloxybenzene discoid [28 a, 51c] ending the century of rod-like dominance d) lyotropic poly(L-glutamic acid) [51 d, 52 k, 1] changing with an alkyl-disorder shell from lyotropic to thermotropic [58e] e) ds A-RNA lyotropic [52n-w, 75] f) am-photropic(L-Lys) /RNA recognition complex [17,18, 75],...

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