The Macromolecular Route to Chiral Amplification

Abstract

Cooperative phenomena, described by one-dimensional statistical physical methods, are observed between the enantiomeric characteristics of monomeric materials and the polymers they produce. The effect of minute energies associated with this amplified chirality, although currently not interpretable, can be easily measured. Nonlinear relationships between enantiomeric excess or enantiomeric content and polymer properties may offer the possibility of developing chiral catalysts and chiral chromatographic materials in which the burden of large enantiomeric excess or content may be considerably alleviated. New approaches to information and sensor technology may become possible.

Molecular chirality at surfaces

“…The small chiral bias and the tendency to avoid energetically unfavorable helix reversals were sufficient to cause this homochirality in the entire polymer. This kind of chiral amplification was coined the ''sergeants-and-soldiers'' principle, because a few units (chiral side chain sergeants) rule the global outcome (single helicity) by cooperatively influencing the sense of helicity of the turns (soldiers) in the entire chain [158]. A similar observation was made for small enantiomeric excess in the side chains and named ''majority rule''.…”

Double screw-sense inversions of helical chiral-achiral random copolymers of fluorene derivatives in phase separating solutions

“…Helical chiral-achiral random copolymers often exhibit interesting chiroptical properties, for example, sergeants-and-soldiers behavior, [18][19][20] composition-driven helical screw-sense inversion, 21,22 and so on. Therefore, the CD induction study in phase separating solution was recently extended to a helical chiral-achiral random copolymer of fluorene derivatives, poly(2,7-[9,9-bis((S)-citronellyl)]-fluorene-random-9,9-di-n-octyl fluorene), as shown in Scheme 1, and double screw-sense inversions were found by changing the chiral monomer content x.…”

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.…”

“…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.…”