7-oxo-pyrido[2,1-i]-purine nucleosides 1a and 1b are highly fluorescent molecules with absorptions and emissions in the visible region. They show little or no cytotoxicity; interactions with isolated enzyme systems could not be detected, and these molecules appear to enter the cell via a purine nucleoside-specific carrier. We demonstrate for one case a specific interaction with cell components. The fluorescence of pyrido[2,1-i]-purine 2 is solvent-dependent and stains the lipophilic parts of a cell.
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.
Abstract6‐Chlorpurin (I) reagiert mit den Estern (II) zu den Derivaten (III), von denen sich (II Ia) in den Ester (IV) überführen läßt. Dieser wird, jeweils in situ hergestellt, mit den Alkinen (V) bzw. (VIII) und (IX) zu den Pyridopurinen (VI) (grüne Fluoreszenz in Lösung) und (VII) bzw. (X) (fluoreszierend) umgesetzt.
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