Photochemistry and Mechanism Study of Coumarin-3-carboxylic Acid as a PhotoCORM

                             Qiuyun Yang,^1 Jiří Váňa,^2 Petr Klán*^,1

 ^1Department of Chemistry and RECETOX, Masaryk University, Kamenice 5, 62500 Brno, Czech Republic

  ^2Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of
                    Pardubice, Studentská 573, 53210 Pardubice, Czech Republic

Coumarins belong to a large family of chemically active compounds. They are widely found in nature,
and thousands of coumarin derivatives have been isolated or synthesized up to now. Coumarin
derivatives exhibit diverse biological activities, such as anticancer, antioxidant, or
antibacterial effects.^1 In addition, the photochemical properties of coumarins have also
extensively been explored and utilized in optical bleaching agents, fluorescent sensors, and
photosensitizers.^2

 In the past decade, therapeutic effects of carbon monoxide (CO) in biological tissues have
extensively been studied. The light-triggered CO liberation from CO releasing molecules
(photoCORMs) is one of the most promising ways, providing a high temporal and spatial release
control. Two promising photoCORMs based on xanthene and BODIPY (Figure 1a and b, respectively)
chromophores have been designed and studied recently by our group.^3

To understand the mechanism of CO release, we decided to use a coumarin moiety as a simplification
of the xanthene photoCORM (a) to extensively study the mechanism of CO release under different
experimental conditions.

Herein, the photochemistry of coumarin-3-carboxylic acid (Figure 1c) as a potential photoCORM has
been investigated. Our study includes the determination of CO release after irradiation at 355 or
420 nm in acetonitrile and methanol. The details about this reaction and the proposed mechanisms of
photolysis will be discussed.

 Figure 1. Structure of photoCOMRs based on a) xanthene, b) BODIPY, c) coumarin-3-carboxylic acid.


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    (b)Kasperkiewicz, K., et al. Lett. Drug. Des. Discovery 2016, 13, 465-474.

3. (a) Palao E., et al. J. Am. Chem. Soc. 2016, 138, 126-133.

    (b) Lovely Angel P. A., et al. Org. Lett. 2013, 15, 4552-4555.