Helix‐Sense‐Selective Polymerization of Achiral Substituted Acetylenes in Chiral Micelles

Abstract

Hold that shape: An achiral acetylene underwent helix‐sense‐selective polymerization in chiral micelles consisting of [{(nbd)RhCl}2] (nbd=2,5‐norbornadiene) and dodecylphenylalanine as a chiral emulsifier to produce optically active helical polymers and polymeric emulsions.

Particles of polyacetylene and its derivatives: preparation and applications

“…[19][20][21][22][23][24][25][26][27][28][29] Polymer particles based on chirally helical substituted polyacetylenes also have been prepared and performed interesting optical activity. Such optically active polymer particles were majorly reported by Deng group [43][44][45][46] and are also included in this review article.…”

“…The major reason for this terrible situation is attributed to the limitations of polyacetylene and a considerable part of the derivatives, i.e. the poor solubility, poor processibility and the 45 low stability particularly against oxygen and heat. [33][34][35] As a consequence, some scientists put forward the concept of processing polyacetylene from polymer emulsions (dispersions) as early as 1980s.…”

Helical Polyacetylenes Induced via Noncovalent Chiral Interactions and Their Applications as Chiral Materials

“…1 for example) whose preferred-handed helical structures are determined through noncovalent chiral interactions under thermodynamic control, the present optically active polyacetylenes with an excess one-handedness ( 23b , 24b ) were produced during the polymerization of monomers with chiral catalysts under kinetic control.

Fig. 8Schematic illustration of helix-sense-selective polymerization of achiral phenylacetylenes ( 23 , 24 ) with chiral Rh catalysts ( a ) and that of an achiral acetylene ( 27 ) in a chiral micelle ( b )(Reprinted with permission from [72]. Copyright 2011 Willey-VCH)

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“…Deng et al utilized chiral micelles consisting of d - or l -dodecylphenylalanine coordinated to [Rh(nbd)Cl] 2 in which achiral N -propargylamides 27 was polymerized in a helix-sense-selective manner, thus producing optically active helical polyacetylenes, whose optical activity was maintained in chloroform after isolation from the micelles [72]. The intramolecular hydrogen bonds between the adjacent pendant urea groups as well as steric repulsions of the pendent groups may stabilize the helical conformation kinetically produced during the polymerization in the chiral micelles as evidenced by the disappearance of their optical activities in a highly polar solvent such as DMF (Fig.…”

Helical poly(phenylacetylene)s containing schiff-base and amino groups: Synthesis, secondary structures, and responsiveness to benzoic acid

“…[2][3][4][5] Substituted polyacetylenes can form helical structures with a predominantly one-handed screw sense by the introduction of appropriate chiral substituents into the side chain or helix-sense-selective polymerization of achiral monomers. [6][7][8][9] Such polymers are of great interest for potential applications as functional materials in molecular recognition, 10 asymmetric catalysis, 11 and chemical sensors 12 based on their electronic and optical properties, which are derived from their conjugated main chain and secondary structures. Since the pioneering work by Ciardelli on helical poly(1-alkyne)s, 6 a variety of helical polyacetylene derivatives based on optically active side groups have been successfully synthesized; for example, poly(alkyl propiolate)s, 13 poly(N-propargylalkylamide)s, 7 poly(N-propargylcarbamate)s, 14 and poly(methylpropargyl ester)s. 15 As examples of dynamic helical polymers, some polyacetylenes undergo helix/random coil transition and/or helix inversion by external stimuli such as temperature, light, and change of medium conditions including polarity and pH.…”