Single‐Handed Double Helix and Spiral Platelet Formed by Racemate of Dissymmetric Cages

Abstract

Spontaneous deracemization has been used to separate homochiral domains from the racemic system. However, homochirality can only be referred to when the scales of these domains and systems are specified. To clarify this, we report self‐assembly of racemates of dissymmetric cages DC‐1 with a cone‐shape propeller geometry, forming a centrosymmetric columnar crystalline phase (racemic at crystallographic level). Owing to their anisotropic geometry, the two enantiomers are packed in a frustrated fashion in this crystalline phase; single‐handed double helices are observed (single‐handedness at supramolecular level). The frustrated packing (layer continuity break‐up) in turn facilitates screw dislocation during the crystal growth, forming left‐ or right‐handed spiral platelets (symmetry‐breaking at morphological level), although each platelet is composed of DC‐1 racemates. The symmetry correlation between DC‐1 molecules, the crystalline phase and spiral platelets, all exhibit C3 symmetry.

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

“…From achiral precursors triamino‐functionalized TABPB and trialdehyde‐containing TP, we synthesized a series of DC molecules with different alkyloxy groups on each terphenyl pillar (Figure 1b), except for DC‐1 without lateral moiety [30] . Each DC molecule is composed of a benzene roof (in blue), a tris( N ‐salicylideneamine) bottom (in yellow), and three terphenyl pillars.…”

Preferential molecular recognition of heterochiral guests within a cyclophane receptor

“…Narcissistic self-sorting, is a well-known phenomenon for supramolecular entities 1,2 and can in most cases be explained by a better shape complementarity between the corresponding molecules of the same configuration, leading to less steric hinderance 3 or increased intermolecular interactions, e.g., dispersion interactions [4][5][6][7][8][9][10] or other driving forces [11][12][13] . In contrast, if enantiomers prefer to bind their mirror image, this is called chiral self-discrimination or heterochiral self-sorting [14][15][16][17][18][19] .…”