Lacunar derivatives of dibenzotetraaza[14]annulene: synthesis and crystal structure of new receptors produced via bis-alkylation of the macrocyclic precursor

The bis(2-hydroxybenzoyl) derivative of dibenzotetraaza[14]annulene was employed as a substrate for producing new lacunar-type receptors. Alkylation of both phenolic OH groups using aliphatic dibromides and ditosylates efficiently leads to the expected bridged products without recourse to a high dilution procedure. Four new dibenzotetraaza[14]annulene-based lacunar receptors, and one unbridged open-chain bis-octoxy analogue have been synthesized. Synthetic procedures, analytical and spectroscopic characterization are reported. Conformations of the macrocyclic rings in the products as well as non-covalent interactions are discussed on the basis of their crystal structures.