Hydrogen bonded PLC structures

Hydrogen bonded PLC structures 3.2.2 Comb-like or side chain architecture... 

A simple application of the self-assembly of complementary bifunctional small molecules to form extended-chain structures, or longitudinal PLCs, is given in references 6-8. Griffin and coworkers report that hydrogen bond-driven association between bispyridyl-terminated and bisbenzoic acid-terminated species can lead to liquid crystalline materials with polymeric characteristics. Typical compounds employed are shown in Figure 3.2. None of the starting components are liquid crystalline. 

Figure 3.14 Structure proposed for a doubly hydrogen-bonded comb-like PLC complex [20].

A comment on Rule 2 also seems needed, since even some researchers working on LC materials believe that LC phase formation requires structures involving primary chemical bonds—while that Rule involves a more general concept of relations. Kato and Frechet [46] and also Bazuin and her collaborators [47,48] have found that hydrogen bonds or ionic interactions are sufficient for the formation of LC phases. Somewhat similarly, Zhao and Lei [49] have obtained ionomers which form simple one-row combs, that is class sO PLCs. Recall also the already mentioned work by Felekis and coworkers [31]. In other words, covalent bonds do not constitute a necessary condition for the formation of LC phases in polymers. 

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