Helical conjugated polymer

Discotic hydrogen bonded complex of l,3,5-tris(l-alkyl-l//-l,2,3-triazol-4-yl) benzene (TTB) and 10,12-pentacosadiynoic acid (PCDA) can form helical conjugated polymers in an asymmetric reaction field consisting of the lamellar columnar LC phase and CPUL (circular polarized ultraviolet light) stimulus (Fig. 5.15) [76]. 

This work opens a new way for preparing helical conjugated polymers in the liquid crystal phase. 

A polymer whisker is a spontaneously formed assembly with a higher-ordered structure and could be used as a single fiber for amplification of the intrinsic properties of the polymer. The whiskers of aromatic polyesters such as poly(para-oxybenzoyl) and poly(2-oxo-6-naphthoyl) have been intensively investigated [31, 32], while there have been only few reports on the whiskers of conjugated polymers such as poly(3-alkylthiophene) [33]. When a helical conjugated polymer with a whisker structure is designed, the intrachain and interchain interactions must be balanced by precisely controlling the van der Waals, rr-electron overlap, and electrostatic interactions. 

K. Suda, J. Yoshida, S. Nimori, K. Akagi, Hierarchical stractures of self-assembled helical conjugated polymers - magnetically forced alignment of liquid crystalline poly(meto-phenylene) derivatives. Synth. Met. 159, 943-948 (2009)... 

Song J, Cheng Q, Kopta S, Stevens RC. Modulating artificial membrane morphology pH-induced chromatic transition and nanostructural transformation of a bolaamphiphilic conjugated polymer from blue helical ribbons to red nanofibers. J Am Chem Soc... 

However, the particular synthetic requirements in the preparation of conjugated polymers have thus far severely limited the number of similarly hierarchically structured examples. Pu et al. reported different types of conjugated polymers with fixed main-chain chirality containing binaphthyl units in their backbone which exhibited, for example, nonlinear optical activity or were used as enantioselective fluorescent sensors [42—46]. Some chirally substituted poly(thiophene)s were observed to form helical superstructures in solution [47-51], Okamoto and coworkers reported excess helicity in nonchiral, functional poly(phenyl acetylenejs upon supramolecular interactions with chiral additives, and they were able to induce a switch between unordered forms as well as helical forms with opposite helical senses [37, 52, 53]. 

Figure 4.11 Schematic representation of the conversion of stranded poly(diacetylene)s with a multiple-helical quaternary the supramolecular polymers into conjugated polymers under structure in the case of A. retention of the hierarchical structure, leading to four-... 

M. J. Marsella, I. T. Kim, F. Tham, Toward Conjugated Double Helical Ladder Polymers Cyclooctatetrathiophene as a Highly Versatile Double Helical Scaffold, J. Am. Chem. Soc. 2000, 222, 974-975. 

Fig. 11.1 Schematic representation of the spontaneous raientation, linear, and helical arrangement of LC conjugated polymers. Reprinted with permission from [17]. Copyright 2013, The...

---