Solvent Effect on the Sergeants-and-Soldiers Effect Leading to Bidirectional Induction of Single-Handed Helical Sense of Poly(quinoxaline-2,3-diyl)s Copolymers in Aromatic Solvents

Abstract

3d(15/85), 93d(20/80), 9 3d(40/60), 9 3d(60/40), 9 and 3d(80/20) 9 and dimethyl(1-bromonaphthalen-2-yl)phophonate (5) 10 were prepared according to the reported procedures. 4-Methyl-1-naphthaleneboronic acid (6) and other chemical reagents were purchased from the commercial sources and were used without further purification. Experimental Procedures and Spectral Data for New CompoundsSynthesis of Polymer 2b(5/100): Qb (1.64 mg, 5.0 µmol) and Q2 (30.04 mg, 100.0 µmol) were dissolved in THF (2 mL). A THF solution of o-TolNiCl(PMe 3 ) 2 (6.43 mM, 156 µL, 1.0 µmol) was added to the monomer solution with vigorous stirring. After 16 h, NaBH 4 (7.94 mg, 210 µmol) was added to the reaction mixture and stirred for 1 h. Water (10 mL) was added to the solution and extracted with CH 2 Cl 2 (15 ml). The organic extract was washed with brine (10 mL), dried over Na 2 SO 4 , and the solvent was

Inducing Enantioselectivity in a Dynamic Catalyst by Supramolecular Interlocking

“…[12] Other examples include enantioselective hydrocyanation reactions reported by Danda et al [13] and Shvo et al [14] as well as as elf-amplifying hydrogenation reaction by our own group. [16] Most commonly found in larger self-assembling structures [17] or helical polymers, [18] it is based on chirality transfer along ac hain of subunits where only few chiral sergeants are needed to align amuch greater number of achiral soldiers to build structures with ahigh degree of stereoselectivity. [16] Most commonly found in larger self-assembling structures [17] or helical polymers, [18] it is based on chirality transfer along ac hain of subunits where only few chiral sergeants are needed to align amuch greater number of achiral soldiers to build structures with ahigh degree of stereoselectivity.…”

“…[15] Another form of chiral amplification, referred to as the sergeants-and-soldiers principle,r elies on the self-organizational ability of supramolecular systems. [16] Most commonly found in larger self-assembling structures [17] or helical polymers, [18] it is based on chirality transfer along ac hain of subunits where only few chiral sergeants are needed to align amuch greater number of achiral soldiers to build structures with ahigh degree of stereoselectivity.…”

Chiral Conflict as a Method to Create Stimuli‐Responsive Materials Based on Dynamic Helical Polymers

“…The design of this material has taken into account not only the opposite helical senses induced by the two chiral monomers in the copolymer,b ut also their dynamic behavior.T he induced helical sense can thus be enhanced, diminished, or inverted by interaction with different stimuli (that is,m etal ions). [16][17][18][19][20][21][22][23][24][25][26][27][28] In such acase,the presence of asmall amount of the chiral monomer (minor component, sergeant) commands the secondary structure of the whole copolymer chain, that is,e ither M or P helices,b yi nducing ac ertain spatial orientation in the achiral units (major component, soldier). [1][2][3][4][5][6][7][8][9][10] Controlled conformational changes at the pendant groups modulate these supramolecular and/or steric interactions, resulting in variations on the helical structure of the polymer, that is,e longation [11][12][13] and/or helical sense.…”

“…[14,15] Thus,c hiral amplification, helical enhancement, or helix inversion can be induced by the action of appropriate external stimuli. [16][17][18][19][20][21][22][23][24][25][26][27][28] In such acase,the presence of asmall amount of the chiral monomer (minor component, sergeant) commands the secondary structure of the whole copolymer chain, that is,e ither M or P helices,b yi nducing ac ertain spatial orientation in the achiral units (major component, soldier). [16][17][18][19][20][21][22][23][24][25][26][27][28] In such acase,the presence of asmall amount of the chiral monomer (minor component, sergeant) commands the secondary structure of the whole copolymer chain, that is,e ither M or P helices,b yi nducing ac ertain spatial orientation in the achiral units (major component, soldier).…”

“…[1][2][3][4][5][6][7][8][9][10] In the case of copolymers formed by the combination of chiral and achiral monomers,t he modulation of the helical structure may occur through ac onformational communication mechanism (going from the chiral to the achiral pendants) that originates ac hiral amplification phenomenon denoted as the sergeants and soldiers effect. [16][17][18][19][20][21][22][23][24][25][26][27][28] In such acase,the presence of asmall amount of the chiral monomer (minor component, sergeant) commands the secondary structure of the whole copolymer chain, that is,e ither M or P helices,b yi nducing ac ertain spatial orientation in the achiral units (major component, soldier). Recently,our group extended the concept of the sergeants and soldiers effect to am ore complex situation of PPAc opolymers;s pecifically, bipolymers,that is,c opolymers derived from two monomers, in which the two components are chiral.…”