Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state

The formation of complex superstructures via hydrogen bonding of two ditopic building blocks, diazadibenzoperylenes 1a,b and isophthalic acid 2, has been investigated. It was found that only the phenoxy-substituted diazadibenzoperylene 1a forms extended assemblies with 2 in complexes of a 1:1 stoichiometry, whereas for the 4-tert-butylphenoxy-substituted analogue 1b, no indications for superstructure formation with 2 were found. The different behavior is explained by the presence of additional pi-pi interactions, which are only observed for [1a x 2], as revealed by concentration-dependent optical absorption and fluorescence spectroscopy. Based on variable temperature x-ray diffraction studies, a lamellar structure for [1a x 2] is proposed that takes into account the concept of microphase-segregation.