Synthesis and electronic spectra of 3-hetaryl substituted coumarin derivatives 7-hydroxy-2H-chromen-2-on and 9-hydroxy-2H-benzo(f)chromen-2-on

The synthesis of 3-hetaryl substituted coumarin derivatives [7-hydroxy-2H-chromen-2-on and 9-hydroxy-2H-benzo(f)chromen-2-on] containing a hydroxyl group by reacting 2,4-dihydroxybenzaldehyde and 2,4-dihydroxynaphtaldehydes with 2-cyanomethylbenzothiazole, 2-cyanomethylbenzimidazole, 1-methyl-2-cyanomethylbenzimidazole and 2-cyanomethyl-4-phenylthiazole is presented. The absorption and steady-state fluorescence characteristics of the synthesised 3-hetaryl substituted 7-hydroxy-2H-chromen-2-on and 9-hydroxy-2H-benzo(f)chromen-2-on in a solution of ethanol and at different pH values are studied to assess their possible application as fluorescent probes for use in molecular biology and medicine.