<i>ansa</i>-Ferrocene-Incorporated Calixpyrroles and Calixphyrins: Syntheses and Spectral/Structural Characterization

The syntheses and spectral/structural characterization of <i>ansa</i>-ferrocene-incorporated <i>normal</i> calixphyrins and <i>core-modified</i> calixpyrroles and calixphyrins are reported. Acid-promoted dehydrative condensation of 1,1′-bis­(dimethylpyrrolylmethyl)­ferrocene and 2,5-bis­(dimethylhydroxymethyl)­thiophene/furan yielded <i>ansa</i>-ferrocene-based <i>core-modified</i> calixpyrroles, while acid-catalyzed dehydrative condensation of 1,1′-bis­(diphenylpyrrolylmethyl)­ferrocene with the aryl aldehydes and 2,5-bis­(phenylhydroxymethyl)­thiophene followed by DDQ oxidation resulted in the formation of <i>ansa</i>-ferrocene-appended <i>normal</i> and <i>core-modified</i> calixphyrins, respectively. The newly synthesized macrocycles were characterized by FAB-MS, NMR, and UV–vis spectral analyses and finally confirmed by single-crystal X-ray structural analysis. All these studies clearly revealed the introduction of ferrocene in the main framework of the corresponding macrocycles in an <i>ansa</i>-type way. The <i>core-modified</i> calixpyrroles adopt a 1,3-alternate conformation, while the corresponding calixphyrins maintained partial planarity along the tripyrrin plane due to the presence of <i>meso</i> sp² carbon and generated curved staircase conformation. In addition to the intramolecular hydrogen-bonding interactions, calixphyrins generate self-assembled dimers, one- and two-dimensional supramolecular assemblies through intermolecular hydrogen bonding in the solid state