Optical and electrochemical properties of novel fused tricyclic thiophene–15-crown-5 systems and their complexes with Mg and Ba ions

New polycyclic aromatic derivatives annulated both with thiophene and with 15-crown-5 ether moieties, crown naphthothiophenes, were synthesized via the Mallory photocyclization with the use of iodine as the mild oxidizer, while two isomeric products were readily separated by column chromatography. Their complexation with Ba²⁺ and Mg²⁺ cations was examined by both optical and electrochemical methods. Spectroelectrochemical studies indicate that the obtained compounds, depending on their structure, can be chemically stable in the oxidized state