Synthesis and Function of Double‐Stranded Helical Polymers and Oligomers

Abstract

The design and synthesis of artificial helical polymers and oligomers has attracted much interest, in connection with fascinating biological helices and their sophisticated functions as well as possible applications in novel chiral materials. The last half-century has seen a significant advancement in the synthesis of single-stranded helical polymers and oligomers, since the discovery of the helical structure of isotactic polypropylene. In contrast, the chemistry of double-stranded helical counterparts is still premature. This paper highlights our recent achievements in the synthesis, structures, and functions of double-stranded helical polymers and oligomers, stressing an important role of supramolecular chemistry in the design and synthesis of double helices with a controlled helical sense.

Tailored Polymer Microstructures Prepared by Atom Transfer Radical Copolymerization of Styrene and N‐substituted Maleimides

“…[1][2][3][4][5][6][7][8][9] The core idea of this new trend is to progress beyond the current state of the art in polymer synthesis and, in particular, beyond the control of macromolecular architecture. For instance, one of the primary goals of the field of precision macromolecular chemistry is to control monomer sequence distribution in synthetic polymer chains.…”

Homo‐double helix formation of an optically active conjugated polymer bearing carboxy groups and amplification of the helicity upon complexation with achiral and chiral amines

“…An extracellular polysaccharide, xanthan, 1 and an ion-channel forming peptide, antibiotic gramicidin A, 2,3 are also known to have a right-or left-handed doublestranded helical structure. Such biological double helices and the resulting sophisticated functions have motivated chemists to develop artificial double-stranded helical oligomers (foldamers) and polymers, [4][5][6][7][8][9][10] although structural motifs for synthetic double helices are still limited to helicates, [11][12][13] peptide nucleic acids (PNAs), 14 aromatic oligoamides, [15][16][17] and oligoresorcinols. 18,19 Recently, we have developed a versatile method to construct complementary double-stranded helical oligomers and polymers linked by a variety of linkages with a controlled helical sense.…”

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.…”

“…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.…”

“…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…”