Effect of spacer length

To clarify the effect of the trans-cis photoisomerization of the chiral azobenzene compounds on the change in HTP, the change in the hehcal pitches of Ch LCs containing nonchiral azobenzene compound, p-azo-7-dl (Fig. 10.7), which was derived with racemic alcohol, was examined. Ch LCs were prepared by adding R811 and chiral or nonchiral azobenzene compounds with the same structure, p-azo-7-dl or p-azo-7, in E44. In the case of the (R811/p-azo-7/E44) sample, the helical pitch was increased by the trans-cis photoisomerization of 

This result indicates that the photochemical change in HTP is related not only to the perturbation effect of the trans-cis photoisomerization on the molecular orientation but also to photochemical change in the intermolecular interaction between the trans or the cis chiral azobenzene molecule and the host LC molecule. 

In general, the smectic A phase has a structure where rod-like molecules pack in diffuse layers where there is no positional ordering of the molecules in the plane and out of the plane of the layers [79]. The only way in which the tetramers can form such a phase is by molecular distortion away from a spherical shape to give a rod-like conformational structuring. Molecular 

The materials with C4 and C spacers exhibited only a smectic A phase, whereas the tetramer with a Cn spacer shows, upon heating, a transition to an additional unidentified phase at 38.7 °C. When the number of methylene units is increased, the isotropization temperatures increase accordingly. The material with the Ce spacer has the lowest solidification temperature (-14.7 °C). Thus these symmetrically substituted systems show low melting 

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Hashimoto, K., Loader, J.E., and Kinsky, S.C. (1986) Iodoacetylated and biotinylated liposomes Effect of spacer length on sulfbydryl ligand binding and avidin precipitability. Biochim. Biophys. Acta 856, 556-565. 

The effects of spacer length on the fluorescence quantum yields of the benzofurazan compounds bearing a donor-acceptor system were reported <2002MI11>. 

Fig. 4 Effect of spacer length on the mean hybridization intensity at five probe lengths. The basic single spacer unit had a length equivalent to a dT OND, so the scale is based on the equivalent number of nucleotides. Intensities were normalized to the intensity obtained using the 25mer probe with no added spacer [20]...

Chlorosulfonated styrene resins and carboxyaminoacid polymers were also found to possess thromboresistant properties by Josefonwicz and coworkers [483]. Studies included investigation of the effect of spacer length between amine and carboxylic groups as well as modification of styrene/isoprene/styrene blocks with chlorosulfonyl isocyanate giving sulfamate and carboxylic functionality [484],... 

Figure 31.12 Effects of spacer length and structure on the ionic conductivities and Tg s for IL monomers and polymers containing polyether spacers. Structures are shown in Figure 31.10. O, EO spacer , PO spacer. Open plots monomers closed plots polymers.

Using these novel LB films, systematic studies have been carried out to elucidate which features of the molecular structures of azo chromophores govern the photoinduced switching of the liquid-crystal alignment.165-169 The effects of spacer length (n) and tail length (m + 1) on the photoresponse of liquid-crystal... 

To provide a test of the effect of spacer length on enzyme activity, a third membrane-enzyme system was formed by reacting the product of the reaction between ethylenediamine and the cellulose ester membrane with suc-cinyl anhydride, then coupling this product to an amine on the enzyme using the carbodiimide route. The product may be represented as ... 

Figure 4 The effect of spacer length on dose dehvery. Fine (< 4.7-pm) and coarse (> 4.7-pm) budesonide particles delivered from a pMDI with a metal spacer of different lengths. The aerosol was analyzed by an Anderson impactor (U.S. throat) 2 s after actuation (28 L/min). The optimal ratio between fine and coarse particles was obtained with a spacer of 13 cm for this particular pMDI. Other pMDIs will have different optimum spacer sizes, depending on vapor pressure.

Saidi, S., Guittard, F., Guimon, C., Geribaldi, S. Fluorinated comblike homopolymers the effect of spacer lengths on surface properties. J. Polym. Sci. A Polym. Chem. 43, 3737-3747 (2005)... 

These networks exhibit a nematic mesophase. Clearly, the type of response to the mechanical field is extremely structure dependent. The effect of spacer length on elastomer behavior was examined [27]. The reported work showed that the coupling between the mechanical stress and polymer backbone can greatly influence the mesomorphic order. This effect can be enhanced by coupling the mesogenic group more tightly to the polymer backbone. 

LIX2 Li, X.D. and Goh, S.H., Specific interactions and miscibility of ternary blends of poly(2-vinylpyridine), poly(Y-vinyl-2-pyrrolidone) and alipl tic dicaiboxyhc acid effect of spacer length of acid. Polymer, 43,6853,2002. 

Craig AA, Imrie CT. Effect of spacer length on the thermal properties of side-chain liquid-crystal polymethacrylates. 2. Synthesis and characterization of the poly[omega-(4 -cyanobiphenyl-4-yloxy)alkyl methacrylate]s. Macromolecules 1995 28 3617-24. 

Figure 4.9 Inhibitory activity of glycopolymers with a) PNA and b) Ctx. MICio values are expressed as total Gal concentration, c) Schematic illustration of the effect of spacer length on inhibitory efficiency. GP glycopolymer MIC50 minimum inhibitory concentration that inhibits 50% of cell isolates and PNA peanut agglutinin, (a and b) Reproduced with permission from B.D. Polizzotti and K.L. Kiick, Biomacromolecules, 2005, 7, 2, 483. 2005, American Chemical Society [116]. c) Reproduced with permission from S-J. Richards, M.W. Jones, M. Hunaban, D.M. Haddleton and M.I. Gibson, Angewandte Chemie International Edition, 2012, 51, 31, 7812. 2012, Wiley [117]...

Fig. 7.6. Effect of spacer length on tacticity in the free-radical polymerization of a methacrylate (After Ref. 39).

Effect of spacer length on thermal properties of siloxane combs Me... 

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