Philippine Journal of Science
151 (5): 1647-1656, October 2022
ISSN 0031 – 7683
Date Received: 24 Mar 2022

Microwave-promoted Synthesis and Optoelectronic
Properties of Ethoxycarbonyl-substituted
Coumarin and Benzo[f]coumarin

Shinje Miñoza, Joshua Andrew P. Nillama*, and Evelyn C. Creencia

Department of Chemistry, College of Science and Mathematics,
Mindanao State University–Iligan Institute of Technology, Iligan City 9200 Philippines

*Corresponding author: joshuaandrew.nillama@g.msuiit.edu.ph

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Miñoza S et al. 2022. Microwave-promoted Synthesis and Optoelectronic Properties of Ethoxycarbonyl-
substituted Coumarin and Benzo[f]coumarin. Philipp J Sci 151(5): 1647–1656. https://doi.org/10.56899/151.05.09

 

ABSTRACT

Microwave-assisted potassium fluoride-catalyzed synthesis of coumarin derivatives via tandem Knoevenagel condensation and intramolecular cyclization was established under solvent-free conditions. Satisfactory product yields were obtained with 67.87 and 90.21% as the highest recorded yields for the target compounds 3a (ethyl 2-oxo-2H-chromen-3-carboxylate) and 3b (ethyl 2-oxo-2H-benzo[f]chromen-3-carboxylate), respectively. The changes in the optoelectronic properties of the synthesized coumarin derivatives relative to the parent coumarin (2H-chromen2-one) molecule were also characterized to study, to some degree, the structure-to-property relationship of the compounds. Generally, extending the π-conjugation at position-3 by adding the ethoxycarbonyl group and expanding the π-system of the coumarin molecule at position-f shifts the absorption maxima to longer wavelengths, decreases the HOMO-LUMO energy band gap, and increases the light absorptivity of the coumarin compound.