Synthesis and functionalization of heteroatom-bridged bicyclocalixaromatics, large molecular triangular prisms with electron-rich and -deficient aromatic interiors.

The synthesis and functionalization of oxygen and nitrogen atom bridged bicyclocalixaromatics of triangular prism structures are reported. By means of a fragment coupling approach, molecular triangular prisms of electron-rich and electron-deficient aromatic interiors were prepared using 1,3,5-tri(p-hydroxyphenyl)benzene and 2,4,6-tri(p-aminophenyl)triazine as base units and chlorotriazines as pillars. Aromatic nucleophilic substitution reaction of chlorotriazine moieties with functionalized amines led to triangular prisms with functionalizations on the peripheral edge positions, while functionalized triangular prisms on the vertex nitrogen positions were obtained using 2,4,6-tri[(p-allylamino)phenyl]triazine derivative as a starting material. Symmetrical and distorted molecular triangular prisms in the solid state were revealed by X-ray crystallography. As evidenced by NMR spectroscopic data, however, all cage molecules synthesized most probably adopted highly symmetric triangular prism structures in solution phase. The functionalized shape-persistent triangular prism structures might find applications in molecular recognition and in the construction of higher and more sophisticated molecular architectures in supramolecular chemistry.