Fig. 2: Representative of the self-assembly process and crystal structure analysis.

a Self-assembly of the hexagonal ring with chiral BINOL-phosphate acid under the basic condition in aqueous solution. b The crystal structure of the hexagon viewed along the c axis with labelled inner size (R-nanotube). c The hexagonal ring packing to the nanotube viewed along the b axis (the yellow color represents the interior channel). d The space-filling nanotube holding two screw axes across the inner center viewed along the a axis (the red color highlights a hexagon or single helix chain corresponding to the screw axis).