Syntheses, Structures, and Anion-Binding Properties of Two Novel Calix[2]benzo[4]pyrroles

Calix[2]benzo[4]pyrrole m‐6 and p‐6, each containing two dipyrromethane moieties and two m‐phenylene or p‐phenylene units, respectively, were readily synthesised from pyrrole, 1,3‐ and 1,4‐bis(1,1′‐dimethylhydroxymethyl)benzene, (m‐4 and p‐4, respectively) and acetone. Macrocycles m‐6 and p‐6 were tested as receptors for a selection of anions, such as acetate, dihydrogenphosphate and fluoride. The X‐ray structures of m‐6 and p‐6 and those of the complexes m‐6⋅F−, m‐6⋅Cl− and m‐6⋅CH3COO− (with an nBu4N+ counterion) were also determined. Novel expanded and hybrid calixpyrroles 1 and 2 were synthesised and tested as hosts for anions. Compound 2 formed 1:1 inclusion complexes with fluoride, chloride, dihydrogenphosphate and acetate (X‐ray structure of 2⋅AcO− is shown here), and it was generally a better host than 1 and the smaller, related calix[4]pyrrole.