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Spectra and photophysics of new organic fluorophores: 2,3-di(phenylethenyl)benzofuran derivatives

Conformations, spectra and photophysics of a series of new organic fluorophores, 2, 3-distyrylbenzofuran derivatives, have been studied by a combined theoretical and experimental approach. Ground electronic state geometries have been investigated by Hartree-Fock ab initio methods and Density Functional Theory. Electronic spectra have been calculated with the CS INDO S-CI and SDT-CI procedures. Spectral and photophysical behaviour has been investigated by stationary and time-resolved techniques. Solvatochromism of these compounds has been analyzed. The UV-Vis absorption spectra of the substituted compounds are very similar, showing a red shift in the series H < Cl < OCH3 < NH2 < NO2. The CS INDO CI analysis of the electronic spectra of all rotamers shows coherence with the prevalent presence of one non planar conformer. These compounds are very stable and show an intense and structured fluorescence indicating that the emitting state is the same as that reached by absorption, i.e. the singlet state. The nitro-derivative behaviour is exceptional if compared to the other compounds since it displays a strong fluorosolvatochromism, due to an intramolecular charge transfer state.

absorption and emission spectra ; intramolecular charge transfer states ; distyrylbenzofurans ; fluorophores ; molecular quantum mechanics ; photophysics ; fluorosolvatochromism

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