Chain number, polycatenars

LC phases usually corresponds to at least the number of attached chains [258]. Moreover, no SmA phases were observed for non-fluorinated polycatenar mesogens, whereas chain fluorination obviously enables the formation of SmA phases, which are most probably of the de Vries type. It seems that non-fluorinated polycatenars are mainly stabilized by core-core interactions, whereas the mesophase stabilization by the fluorophobic effect retains the layer structure even if core-core interactions are relatively weak. 

The study of 126 was later followed up by reports of the behavior of the related Pd(ll) and Pt(ii) complexes 127-in which the authors set out to investigate the transition from the behavior associated with calamitic materials to that associated with more disk-like materials (Figure 38). The results, summarized in Table 23, show that it is both the number and distribution of chains on the /3-diketonate that determine the transition to disk-like behavior. Interestingly, none of the complexes show behavior characteristic of both rods and disks as found in polycatenar systems2 2" (see 12.05.3.5). 

Fig. 5.30 Development of mesophase strueture including vesicle-like columnar and micellar cubic phases depending on the length and number of the C-terminal chains and the length of the N-terminal chains and the structure of the linking group X of polycatenar imidazolium salts 90. Reproduced from Ref. [198] by permission of The Royal Society of Chemistry...

Compounds with 2,4-disubstituted endstanding benzenes are the bridge to substances with several endstanding chain-like substituents, now called polycatenar compounds (Table 2.3). It seems that the symmetry of the mesophases depends on the number of paraffinic chains in comparison to the core size. " Polycatenar molecules having four to six long paraffinic chains are a good example of this idea since they present a smectic and... 

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