A series of triptycene-derived diazadioxacalixarenes were synthesized by two-step S_NAr reactions from 2,7-diaminotriptycene, 2,7-dihydroxytriptycene with heterocyclic compounds such as cyanuric chloride, 1,5-difluoro- 2,4-dinitrobenzene and 2,6-dichloropyridine-3,5-dicarbonitrile, respectively. X-Ray crystallographic analysis of the trimer obtained by reaction of 2,7-diaminotriptycene with 2,6-dichloropyridine-3,5-dicarbonitrile showed that the two pyridine rings are in the same side of the triptycene unit and the two residual chloride atoms point to the same direction, which greatly favors the subsequent cyclization reactions with 2,7-dihydroxytriptycene. Due to the 3D characteristic of triptycene unit, the synthetic macrocyclic molecules are pairs of diastereomers. Their structures and self-assembled properties were studied by NMR spectra and X-ray crystallographic analysis. The results showed that the diazadioxacalixarenes have some different properties from those of tetraazacalixarenes and tetraoxacalixarenes. The triptycene-derived tetra-NH-bridged azacalixarenes obtained from the reaction of 2,7-diaminotriptycene with 2,6-dichloropyridine-3,5-dicarbonitrile can self-assemble into a large square-shaped organic nanotube with aromatic single-walled surfaces by four in?nite one-dimensional H-bond chains, and the nanotubes could further assemble into a 3D honeycombed architecture. However, the diazadioxacalixarene analog could not self-assemble into such architecture due to the structural and conformational changes made by the displacement of two bridging nitrogen atoms with oxygen atoms, which led to the destroy of the H-bond chains formed from the bridging NH groups with the cyano groups. Our results also showed that the trimer of 2,7-diaminotriptycene and 2,6-dichloropyridine- 3,5-dicarbonitrile could self-assemble into a nanotube architecture with a hole diameter of 8.16 Å×8.95 Å through C—H…Cl H-bond (d_H…Cl＝2.87 Å, θ_C—H…Cl＝149.31°), π…π (d_π…π＝3.67 Å) stacking and C—H…π (d_C—H…π＝2.86 Å) interactions.

Key words: triptycene, heteracalixarenes, synthesis and structures, molecular assembly, diazadioxacalixarenes