Complexation of Selected Polycyclic Aromatic Hydrocarbons with Hexaprotonated Hexaazacyclophane Macrocycles


Keywords: Supramolecular chemistry, Host-guest chemistry, Job’s plot, Benesi-Hildebrand method, Stern-Volmer plot.

How to Cite

M. Kumarasinghe, D. ., D. Lekamge, D. ., P. Rajapaksha, S. ., & R. Fernando, I. . (2023). Complexation of Selected Polycyclic Aromatic Hydrocarbons with Hexaprotonated Hexaazacyclophane Macrocycles. Jordan Journal of Chemistry (JJC), 18(1), 33-42. Retrieved from


Abstract: This research focused on the host-guest complexation-driven detection of three selected polycyclic aromatic hydrocarbons (PAHs), naphthalene, anthracene and phenanthrene, in solution using two protonated hexaazacyclophane macrocycles (16+), specifically 1a6+ and 1b6+. The geometry optimization of PAHs and 16+ performed using quantum chemical density functional theory calculations demonstrated their electronic compatibility to undergo host-guest complexation. The macrocycles 1a6+ and 1b6+, which possess different cavity geometries, were synthesized using [2+2] Schiff-base cyclization of diethylenetriamine separately with terephthalaldehyde and isophthalaldehyde, respec­tively, followed by reduction and protonation. After spectroscopic characterization of the macrocycles, the fluorescence spectroscopic determination of stoichiometry, binding constant and quenching constant between 1a6+/1b6+ and PAH was performed using the Job’s plot method, Benesi-Hildebrand method and Stern-Volmer plot, respectively. The stoichiometry of each combination of 16+ with PAH exhibits a 1:1 complexation. Among the PAHs studied, phenanthrene demonstrated the highest binding and quenching constants with both 16+, while anthracene and naphthalene showed the lowest binding and quenching constants, respectively, with both 16+. The cavity geometry of 16+ and the shape and number of fused rings of PAHs contributed to the binding constant.