Crystal Engineering and Photophysical Properties of Phenyl-Pyrenoimidazole Systems

A series of π-conjugated phenyl-pyrenoimidazole (Py-Im) systems was synthesized through a one-pot condensation reaction between 4,5-pyrenedione and various benzaldehyde derivatives. The single crystal structures of these Py-Im compounds were determined and the results showed that Py-Ims can serve as versatile supramolecular synthons for the formation of diverse solid-state structures, ranging from linear hydrogen bonded networks to complex helical hydrogen bonded networks and layered π--π stacking assemblies. The crystallographic structures exhibit correlation to the nature of substituent groups attached to the Py-Im systems, while the dominant intermolecular forces that dictate their solid-state packing can be reasonably accounted for by molecular electrostatic potential (MEP) analysis. Photophysical properties of these Py-Im derivatives were examined by UV-Vis absorption and fluorescence spectroscopy. Our studies disclosed that weak-to-moderate electron-donating/withdrawing groups have insignificant eff...