Helical Polymers: Synthesis, Structures, and Functions

Abstract

Figure 13. Structures of poly(dialkylsilane)s with different main-chain stiffness (74s76) and schematic illustrations of stiffness-dependent polymer wrapping behavior onto SWNT by the high-speed vibration milling (HSVM) method. (Reproduced with permission from ref 133.

Stirring competes with chemical induction in chiral selection of soft matter aggregates

“…A chiral modifier, chemically compatible with the host system, is often employed to imprint an achiral mesophase with a well-defined handedness 11 . For instance, on using a chiral mesogenic molecule as a dopant, a nematic liquid crystal phase will convert into a chiral nematic or cholesteric phase, in which the average molecular orientation develops a spatially organized helical arrangement, with a characteristic pitch and twist sign, which depend on subtle non-covalent interactions between the modifier and the host system 12 .…”

Dynamic Helicity Control of Oligo(salamo)-Based Metal Helicates

“…If the chiral group is relatively small compared with the helix, we can shift the equilibrium while keeping the P and M helices as the approximate mirror image of each other. This is the basic concept of the dynamic helicity control, which has been used to obtain one-handed forms of various dynamic helical structures such as metal helicates and helical polymers [16,17]. Since the P and M forms are in dynamic equilibrium, we can change the P/M equilibrium ratio by the addition/removal or modification of the chiral auxiliary.…”

Chiral amplification in double-stranded helical polymers through chiral and achiral amidinium–carboxylate salt bridges

“…[1][2][3] Although a large number of singlestranded helical polymers and oligomers have been reported, [2][3][4][5][6][7][8][9][10][11][12] examples of double-stranded helical polymers and oligomers remain relatively scarce. 2,3,8,9,[13][14][15][16][17][18][19][20][21][22] We have recently reported on the rational design and synthesis of a series of complementary double-stranded helical oligomers [23][24][25][26][27][28] with an optical activity that consists of a crescent-shaped m-terphenyl-based backbone containing amidine and carboxylic acid groups. In our design, the formation of the intertwined duplex is driven by the formation of an amidiniumcarboxylate salt bridge, and the helicity of the duplexes can be readily controlled by the introduction of chiral substituents on the nitrogen atoms of the amidine residues.…”

“…9,15,18,19 We also reported on mterphenyl-based conjugated polymers, which contain optically active amidine groups (poly-A 1 ) and achiral carboxylic groups (poly-C), that folded into an intertwined double-stranded helical structure through the chiral amidinium-carboxylate salt bridges. 29 In this study, we synthesized a series of m-terphenyl-based random copolymers containing chiral and achiral amidines (poly-A x ) and their complementary homopolymers containing achiral carboxylic acids (poly-C), and investigated the effect of the chiral/achiral amidine contents on the amplification of the helical chirality 30,31 during the complementary double-helix formation ('the sergeants and soldiers effect') 3,4,32,33 (Figure 1) using absorption and circular dichroism (CD) spectroscopies. Such a unique amplification of the helical chirality along the polymer backbones assisted by a small chiral unit has been proven to be applicable to some stiff single-stranded helical polymers 3,7,9,[31][32][33][34][35][36][37][38][39] and supramolecular helical systems.…”

“…29 In this study, we synthesized a series of m-terphenyl-based random copolymers containing chiral and achiral amidines (poly-A x ) and their complementary homopolymers containing achiral carboxylic acids (poly-C), and investigated the effect of the chiral/achiral amidine contents on the amplification of the helical chirality 30,31 during the complementary double-helix formation ('the sergeants and soldiers effect') 3,4,32,33 (Figure 1) using absorption and circular dichroism (CD) spectroscopies. Such a unique amplification of the helical chirality along the polymer backbones assisted by a small chiral unit has been proven to be applicable to some stiff single-stranded helical polymers 3,7,9,[31][32][33][34][35][36][37][38][39] and supramolecular helical systems. 30,[40][41][42][43][44] In some artificial double-stranded helical oligomers, an excess of the one-handed helical structure was produced by a small number of chiral units that were introduced into an achiral strand.…”