Rectangular phases

By reduction of 93 [106] with BH3-THF, Lattermann was able to obtain tridentate [9]-N3 derivative 100 [113] (Scheme 49). While the host system 100 is only crystalline, complexation with Ni(N03)2 induced a columnar rectangular phase as confirmed by X-ray scattering experiments. 

Compound 114d possesses significantly lower transition temperatures (Scheme 60) due to the branched side chains [126]. A columnar phase is present even below room temperature. At 14 °C, anew chiral columnar phase was observed while above 111 °C, an achiral columnar rectangular phase was observed. The spiral-pattern texture of 114d in the chiral Col mesophase is shown in Fig. 17. 

Note that in the original publications the interpretation of the X-ray results is not correct. Instead of a hexagonal phase the given X-ray data point to a rectangular phase with much smaller parameters compared to the molecular diameter. For the molecule with octyloxy chains the dimension of the column would be about 4.0 nm compared to a diameter of 5.2 nm for the molecule. 

Fig. 19. Rectangular phase diagram of TC-L systems in 0.15 M NaCl at 20°C. Region I corresponds to concentrations where simple and mixed micelles coexist. In region II only mixed micelles are present, and in region III metastable vesicles and liposomes are found. (From ref. 102 with permission.)...

Figure 12. Schematic representations of (a) centered rectangular phase, (b) representation of six connected rhombohedral mesh phase.

Figure 1 Phase diagrams at 25°C of four ternary systems, (a) Water-pentanol-SDS. (From Refs. 22 and 23.) (b) Water-hexanol-SDS. (From Refs. 22 and 23.) (c) Water-octanol-SDS. (From Ref. 79.) (d) Water-decanol-SDS. (From Ref. 80.) Lj, L2, isotropic phases H, hexagonal phase R, rectangular phase L , lamellar phase L4, vesicle phase N, nematic phase. The dashed boundaries have not been determined accurately. is a critical point.

Phase-Shift Lithography, Fig. 4 SEM images of fabricated PR patterns by roll type phase shift lithography by rectangular phase mask (a), by circular phase mask (b),... 

Oblique and Rectangular Phases The first example of an oblique columnar phase has been observed on the first phasmid described (5, = 7, Table 1). A central terephthalylidene ring fitted with two ben-zoyloxyphenylimines seems to favor phases (Tables 1, 5 and 9). Regarding the rectangular columnar mesophase, chain-rich polycatenars such as phasmids do not display this mesomorphic symmetry, which so far has appeared only in the biforked tetraester series 19. 

Raman experiments, antiferroelectrics 667 randomly constrained nematics 189 Rapini-Popular terms 77 rational routes, hydrocarbon cores 705 Rayleigh interferometer 131 Rayleigh scattering 172 reagents, hydrocarbon cores 694 ff rectangular phases... 

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