Cross-sectional observations of the cholesteric texture in a Cano wedge cell

A novel procedure for an observation of a liquid crystal texture is proposed by using a UV curable liquid crystal. Optical observations from a cross-section of the Cano wedge cell are demonstrated and layered structures of cholesteric LC are visualized clearly. The structures near the Grandjean lines are then revealed in detail from images. From the observations, it is confirmed that the texture near the Grandjean line is similar to fingerprint texture     

Thermal decomposition of poly(sec-amyl methacrylate)

The thermal decomposition of poly(sec-amyl methacrylate) is studied by simultaneous thermogravimetry–gas chromatography–mass spectrometry and by pyrolysis–gas chromatography. The TG curve has four distinct breaks and a plateau. Results of the identification of the evolved gas at the individual breaks by GC–MS techniques lead to the conclusion that these breaks correspond to the individual processes in the decomposition mechanism like that of poly(tert-butyl methacrylate): the first break, the depolymerization initiated at the unsaturated chain ends; the second break, the depolymerization initiated at the saturated chain ends; the third break, the ester decomposition; the plateau, the inhibition of decomposition by the formation of poly(methacrylic anhydride); the fourth break, the decomposition of poly(methacrylic anhydride). The extent of ester decomposition is related to the substituent constants based on Hammett equation. The ester decomposition product is separated into three pentene isomers by pyrolysis–gas chromatography: trans-2-pentene, cis-2-pentene, and 1-pentene. As raising decomposition temperature, the composition ratio of trans-2-pentene decreases and becomes constant above 620 K, and the composition ratios of cis-2-pentene and 1-pentene increase and also become constant above 620 K. These results are accounted for by mobility of atoms included in the substituent at forming a ring transition state.     

Mixed-valence states of 11, 1111-dialkyl- and 11, 1111-bis(methylbenzyl)biferrocenium triiodides

It was found that the packing of cations and anions influences the electronic structures of mixed-valence binuclear ferrocene derivatives. Temperature-dependence of the mixed-valence state of 1¹, 1¹¹¹-diisobutylbiferrocenium triiodide was observed in a crystalline state, whereas only a trapped-valence state was found in a dispersed state. The packing effect was also observed for a series of 1¹, 1¹¹¹-dialkyl- and 1¹, 1¹¹¹-bis(methylbenzyl)biferrocenium triiodides by means of ESR spectroscopy.     

Studies of molecular motions in the three phases of 1,1′,2,2′-tetrachloroferrocene by Mössbauer and1H-NMR spectroscopy

The molecular motions in the three phases of 1,1′,2,2′-tetrachloroferrocene below m.p. were studied by using⁵⁷Fe-Mossbauer and¹H FT-NMR spectroscopy. In the plastic phase at the low temperature, a rotational mode around the pseudo C₅ molecular axis was found to be activated with activation energy of 15 kJ/mol and in the higher temperature phase the rotational mode of the pseudo C₅ axis itself was found to be activated with activation energy of 23 kJ/mol in addition to the rotational mode around the pseudo C₅ axis. On the⁵⁷Fe-Mossbauer spectra, a steep decrease of the areal intensity was observed above the first transition temperature. The areal intensity in the lower plastic phase was estimated to be less than a few percent relative to that at 298 K. The results were discussed in terms of different possibilities for the movement of the molecules.