Molecular Architecture towards Helical Double‐Stranded Polymers

Abstract

Nahe am Original: Ein DNA‐ähnliches doppelsträngiges Polymer wurde durch Ringöffnungsmetathesepolymerisation eines Bisnorbornens mit starrem Ferrocen‐Spacer synthetisiert. Das Polymer bildet Helices (siehe Bild), Supercoil‐ und Leitermotive, wie durch Rastertunnelmikroskopie nachgewiesen wurde.

From Polynorbornene to the Complementary Polynorbornene by Replication

“…Polymer 13 represents the first unsymmetrical double‐stranded polymer in which the two constituent strands are complementary to each other and linked by the ferrocene units. Unlike 2 ,8 only ladderlike structures were observed by STM for 13 , and neither helical nor supercoiled structures were observed in the STM images. The relationship between the structure of the double‐stranded polymer and the solid‐state morphology remains unclear at this stage.…”

“…(1)]. 8 The structure of 2 was unambiguously proved by chemical hydrolysis, spectroscopic means, and STM images. It is noteworthy that the linker between two norbornene moieties in 2 is derived from 4‐aminobenzyl ester and ferrocene dicarboxylate.…”

“…The aminobenzyl fragment in 2 is known to be particularly labile towards hydrolysis9 to afford the corresponding single‐stranded polymer 3 and ferrocene dicarboxylic acid 4 [Eq. (1)] 8 …”

“…We have previously shown that the ferrocene moiety provides a unique linker for double‐stranded polymers because it may serve as a filling to prop up the two polymeric backbones. Moreover, the ferrocene unit may increase the solubility of the polymer because of the flexibility of the skeleton that results from twisting of the two cyclopentadienyl ligands 8. Accordingly, we have incorporated the ferrocene moiety into the single‐stranded polymer (Scheme ).…”

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.…”