Methoxybiphenyl mesogens

Our group investigated the influence of the spacer length of 2,3-disubsti-tuted norbornene derivatives with cyanobiphenyl-mesogenic units [42] and with methoxybiphenyl-mesogenic units [43] on the mesophases. Exo,endo-his-[(4 -cyanobiphenyl-4-yl)oxy-n-alkyl]norborn-5-ene-2,3-dicarboxylates with different alkyl spacer lengths (IV-n, n=2-12) were synthesized in a straightforward manner. 

Fig. 21.8 Structure of DiPEG-BP LC polymer (a) and TEM micrograph of Ag NPs within (b) (Adapted with permission from Lee and Jin (2003)). Molecular structure of side chain LC polymo-used by Barmatov et al. (2004) incorporating cyanobiphenyl or methoxybiphenyl mesogens (c) and TEM micrograph of Ag NPs synthesized within (d)...

Poly(epichlorohydrin) (PECH) and poly(2,6 - dimethyl-1,4-phenylene oxide) (PPO) containing pendant mesogenic units separated form the main chain through spacers of zero to ten methylene units were synthesized and characterized in order to test the "spacer concept." Both polymers were modified by phase transfer catalyzed esterifications of the chloromethyl groups (PECH) or the bromobenzyl groups (brominated PPO) with potassium co -(4-oxybiphenyl) alkanoates and potassium u-(4-methoxy-4-oxybiphenyl)-alk.an oates. While PPO required ten methylene units as a spacer and 4,4 -methoxybiphenyl as mesogen to present thermotropic liquid crystalline mesomorphism,... 

Biphenyl mesogens with R=CN [(4 -cyanobiphenyl-4-yl-)oxy-] or R=OCH3 [(4 -methoxybiphenyl-4-yl)-oxy-] were attached to norborn-2-ene moieties, and separated by different spacer lengths and carboxylic acid ester, ether or imido-groups as anchoring moieties, as shown in Fig. 4. 

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