✦ LIBER ✦

Influence of the solvent on the emission of 3-(N,N-dimethylamino)-2H-1-benzopyran-2-one

✍ Scribed by A. Gáplovský; P. Hrdlovič; J. Donovalová; P. Hrnčiar

Publisher: Elsevier Science
Year: 1991
Tongue: English
Weight: 661 KB
Volume: 59
Category: Article
ISSN: 1010-6030
DOI: 10.1016/1010-6030(91)87010-s

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✦ Synopsis

3-(iV,ZV-dimethylamino)-2H-1-benzopyran-2-one (DMAC) exhibits a relatively strong shortlived emission (A,, ~460 nm; lifetime, 0.2 ns) in non-polar solvents with a Stokes? shift of about 8000 cm-'. In more polar solvents, the emission shifts, bathochromically (Stokes' shift up to 10 000 cm-' and lifetime of 0.5 ns). Polar protic solvents quench the fluorescence and the quenching can be quantitatively described by a Stern-Volmer dependence. The bimolecular quenching rate constants are lower than those controlIed by diffusion. The monomethyl derivative 3-(N-methylamino)-2H-l-benzopyran-Zone (MAC) exhibits emission in non-polar and polar solvents which is hypsochromically shifted with respect to DMAC (&x = 400 nm; Stokes' shift around 4000 cm-')

and is short-lived (less than 0.1 ns). The fluorescence of DMAC and MAC originates in the intramolecular charge-'tradsfer state.

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