meta-dihalogenated benzene and heterocycles. Single-crystal X-ray analysis revealed that oxacalix[2]terphenylene[2]pyrazine 13 adopts a chair conformation, forming a molecular cavity to trap an ethyl acetate guest molecule in the solid state. 1,3-Alternate conformations are adopted by other oxacalix[2]terphenylene[2]aromatics (11, 12 and 15), which form a narrow tweezer-like molecular cavity that is incapable