Photophysical properties of fluorescent pyrido[2,1-i]purines

Abstract

7-0~0-3-(tetrahydropyranyI-2-yl) -7H-pyrido[2,1 -;]purines (1 ) are highly fluorescent molecules with absorption and emission in the visible region. Quantum yields range from 0.33 to 0.64, while fluorescence lifetimes are rather short (2-6 ns). An increase in solvent polarity shifts absorption to shorter and emission t o longer wavelengths. From this a change in dipole moment of 5.5 D could be estimated between ground and excited states of (1 b). Fluorescence is quenched by tertiary amines via electron transfer. Hydrolysis of the protecting tetrahydropyranyl function results in a pyridopurine with somewhat different properties.