Molecular Shapes of Monosubstituted Polyacetylenes in their Liquid Crystalline Phases

Abstract

In this short review, we discuss the molecular shapes of monosubstituted polyacetylenes (MSPAs) in their liquid crystalline (LC) phases. Their rigid backbone with high stereoregularity can endow MSPAs with significant shape persistency, which largely determines their LC structures. Helical cis‐cisoidal and cis‐transoidal MSPAs render rod‐like shapes and can form columnar LC (Φ) phases. In the smectic LC (Sm) phases of MSPAs with mesogenic side‐chains, the main chain, with trans‐cisoidal, trans‐transoidal or extended cis‐transoidal conformation, is in fact largely coplanar with the side‐chains, resulting in a sheet‐like molecular shape. From a simple geometric point of view, the rod‐ or sheet‐like MSPA molecules serve as the building block of their LC phases.magnified image

A new class of nanostructured supramolecular organic semiconductors based on intertwined multi-lamellar co-assemblies in π-conjugated liquid-crystalline side-chain polymers

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The first class of materials takes advantage of the block copolymer's ability for phase separation into well-ordered morphologies (spherical, cylindrical or lamellar) to form separate conduction pathways for charge carriers, thanks to the antagonistic chemical nature of each block at the origin of the nanosegregation. [24][25][26][27] However, the optimal charge transport properties also require the formation of long-range correlated structures with an orientational control of regular pathway alternation.…”

Copolymerization of chiral propargylethers and N-propargylamide and conformational control of the copolymers

“…Helically chiral polyacetylenes involve particular structures and morphology, which can be used in the several different fields on optical and stimuli-responsive materials, chiral cognition, biosensor [14][15][16][17]. Poly(phenylacetylene) derivatives bearing a chiral pendant have been designed to form the consecutive one-handed twist of the main chain induced by chiral molecules [18][19][20].…”

Synthesis and characterization of poly(phenylacetylenes) featuring activated ester side groups

“…Attachment of appropriate pendant groups or substituents to the polyacetylene backbone cannot only help to improve the processability and stability but also equip it with new functionalities. While the polyacetylene backbone with its conjugated double bonds is electronically conductive,13 introduction of pendant functional groups may provide novel properties and interesting chemical characteristics to the polymers, which are absent in the parent form, for example, photo‐ and electroluminescence,14, 15 optical activity,16–18 liquid christallinity18–20 or anion sensing property 21, 22. Such multifunctional polymers have been receiving an increasing amount of attention in material and life science.…”

“…The group of Theato as well as other groups have demonstrated the synthetic potential of polymeric activated esters in combination with controlled radical polymerization techniques 27–30. Especially pentafluorophenyl (PFP) esters proved to be useful because they combine several synthetic advantages: (i) excellent solubility in common organic solvents, (ii) possibility to store PFP ester polymers for a long time without the potential risk of hydrolysis of the ester bond, (iii) quantitative and selective conversion with amines under mild conditions and (iv) easy analysis using19F NMR and IR spectroscopy.…”