Synthesis and Polycyclic Aromatic Hydrocarbons Binding Study of Protonated Polyaza Macrocycles

Posted: 2 Dec 2019

See all articles by IR Fernando

IR Fernando

Department of Chemistry, Faculty of Applied Sciences, University of Sri Jayewardenepura

WMDM Kumarasinghe

Faculty of Graduate Studies, University of Sri Jayewardenepura

Date Written: December 2, 2019

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a group of hydrogen and carbon-containing organic compounds which consist of two or more fused aromatic rings. The PAHs originate from the natural- as well as anthropogenic- sources are accumulated in the environment while causing adverse effects on the human health. Among the chemical methods that are employed to detect and sequester the PAHs, the host-guest complex formation between PAHs ‘guests’ and macrocyclic ‘hosts’ are yet to be explored. Therefore, the main objective of this research project was to develop a donor-acceptor interaction driven host-guest chemistry-based method to scavenge a range of electron-rich PAH ‘guests’ using a series of electron-deficient protonated polyaza macrocyclic ‘hosts’ which possess different cavity sizes. The synthetic design of the electron-deficient protonated polyaza macrocyclic ‘hosts’ starts with the synthesis of a series of macrocycles of Schiff-bases (MSB 1-3) by reacting a dialdehyde, terephthalaldehyde with three different terminal diamines, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, followed by the reduction of MSBs with NaBH4 and the protonation with HBr to obtain the corresponding polyaza macrocycles (PAZ 1-3) and protonated polyaza macrocycles (PPAZ 1-3), respectively. In the Fourier transform infrared spectrum of MSB 1, the disappearance of a –C=O peak of terephthaldehyde around 1730 cm-1 and the appearance of a new –C=N peak around 1640 cm-1 confirmed the macrocyclic Schiff-base formation. The peaks at H 8.297 (–CH=N), 7.537 (aromatic H), 3.797 (–CH2-N=), 3.005 (–CH2-NH) ppm of the Proton Nuclear Magnetic Resonance Spectra of MSB 1 further confirmed the cyclization. Preliminary qualitative binding studies between PPAZ 1 with PAHs — naphthalene, anthracene and phenanthrene — were monitored using UV-visible spectroscopy and results suggest that some of the PAHs in the organic layer transferred to the aqueous layer. In order to confirm the host-guest inclusion complex formation in aqueous layer, further studies need to be carried out.

Keywords: polycyclic aromatic hydrocarbons, host-guest chemistry, macrocyclic schiff-bases, polyaza macrocycles, inclusion complexes

Suggested Citation

Fernando, IR and Kumarasinghe, WMDM, Synthesis and Polycyclic Aromatic Hydrocarbons Binding Study of Protonated Polyaza Macrocycles (December 2, 2019). Proceedings of the 6th International Conference on Multidisciplinary Approaches (iCMA) 2019 | Faculty of Graduate Studies, University of Sri Jayewardenepura. Available at SSRN: https://ssrn.com/abstract=3496512

IR Fernando (Contact Author)

Department of Chemistry, Faculty of Applied Sciences, University of Sri Jayewardenepura ( email )

Sri Lanka

WMDM Kumarasinghe

Faculty of Graduate Studies, University of Sri Jayewardenepura ( email )

Sri Lanka

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