A Pair of Interconverting Cages Formed from Achiral Precursors Spontaneously Resolve into Homochiral Conformers

Abstract

Without chiral induction the emergence of homochirality from achiral molecules is rather serendipitous, as the rationale is somewhat ambiguous. We herein provide a plausible solution. From achiral precursors are formed a pair of interconverting cage conformers that exhibit a C 3 -axis as the only symmetry element. When their interconversion is impeded with intramolecular H-bonding, each conformer self-sorts into a homochiral crystal, which is driven by a helical network of multivalent intermolecular interactions during the self-assembly of homochiral cage conformers. As no chiral induction is involved throughout, we believe our study could enlighten the rational design for the emergence of homochirality with several criteria: 1) formation of a molecule without inversion center or mirror plane; 2) suppression of the enantiomeric interconversion, and introduction of multivalent interactions along the helical trajectory of screw symmetry within the resulting superstructure.

Spontaneous Symmetry Breaking of Achiral Molecules Leading to the Formation of Homochiral Superstructures that Exhibit Mechanoluminescence

“…Each Around the crystallographic b-axis, each FPy molecule rotates by 180° with respect to another, so that they are packed in a head-to-tail manner along the helical trajectory, forming a chiral supramolecular 21-helix, in line with our previously proposed strategy of "go with the flow". 18 The helices are extended on the ac plane to afford the chiral polar monoclinic crystalline phase (Figure S9).…”

“…Given over 60% of noncentrosymmetric crystals (41/65 Sohncke space groups) exhibit screw symmetry, we recently proposed a strategy that favors spontaneous chiral resolution of racemic molecules, which we termed "go with the flow": 18 When rational molecular design facilitates the exerting of multivalent intermolecular interactions along the helical trajectory of screw symmetry of the molecular packing, the racemates could experience narcissistic self-sorting during crystallization, leading to the formation of homochiral conglomerates. We also applied this strategy to a series of achiral D-A molecules.…”

Double winding vine-shaped biphenyl with molecular asymmetry. Synthesis, structure, and properties

“…Accordingly, chirality switching employing organic compounds involving molecular asymmetry can be translated into digital information without changing its chemical property except the absolute configuration. [6][7][8][9][10] We have reported that the ring-closing metathesis (RCM) of (hetero)biaryl bearing a terminal alkenyl substituent at each aromatic ring undergoes a cyclization reaction and the thus formed product indicates molecular asymmetry. We have been studying the thus obtained cyclized product, which we call such a kind of chirality as the winding vine-shaped molecular asymmetry.…”