The direct synthesis of a substituted naphthopentathiepin for selective Co2+ ion recognition in aqueous solution

Abstract

A new pentahiepin based on 1-naphthol unit was synthesized by direct condensation method, which on crystallization yielded triclinic crystals in the P-1 space group. The crystal structure was analyzed computationally through Gaussian and CrystalExplorer software. An unusually high degree of short contacts originating from sulfur were observed. The intermolecular interaction investigations revealed that the sulfur atoms take a chair form suitable for metal coordination. Investigation of the affinity of the naphthopentathiepin towards metal ions revealed that the receptor forms a complex with Co2+ ions in 50% aqueous acetonitrile. By virtue of the cage type cavity offered by the pentathiepin derivative, it can form a complex with Co2+ ions in a sandwich fashion. The Job’s plot confirmed 2:1 binding stoichiometry.