Photolytic release of bioactive carboxylic acids from fused pyran conjugates

- Coumarins with amino and aryl substituents were synthesized and used in the derivatization of glycine and β-alanine.
- The new ester cages, as models of carboxylic acid bioactive molecules, revealed to be interesting photo-responsive units.
- A remarkable behaviour towards irradiation at higher wavelengths occurred in conjugates bearing the styryl-coumarin.
- Time-resolved fluorescence studies revealed different fluorescing species by the determination of decay associated spectra.
- This study shows new promising alternative moieties for the development of photoactivable fluorescent acid prodrugs.

New ester cages bearing the coumarin (2H-benzopyran-2-one) skeleton with extended π-systems as phototriggers, for glycine and β-alanine, as models of carboxylic acid bifunctional molecules with biological relevance, were evaluated under photolysis conditions at 254, 300, 350 and 419 nm of irradiation in a RPR-100 photochemical reactor. The processes were followed by HPLC-UV detection and 1H NMR with collection of kinetic data. The results showed a correlation between the photolysis efficiency and the increasing extension of the conjugation for both glycine and β-alanine, showing that the 7-aminocoumarin afforded the best results at all wavelengths tested.From a study of the time-resolved fluorescence behaviour, these compounds were also found to exhibit more complex fluorescence decay kinetics. This was attributed to the presence of conjugated and non-conjugated coumarin species.

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