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Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064


FERREIRA, Luis Filipe Vieira; LEMOS, Maria João; WINTGENS, Veronique  and  NETTO-FERREIRA, José Carlos. Diffuse reflectance technique applied to a fluorescence study of n-alkyl substituted 2,3-naphthalimides included in b-ciclodextrin and adsorbed in microcrystalline cellulose. Quím. Nova [online]. 1999, vol.22, n.4, pp.522-528. ISSN 0100-4042.

The solution fluorescence of N-alkyl-2,3-naphthalimides (1-4) in polar protic and aprotic solvents was compared to the emission from solid samples resulting from the imide complexation with b-cyclodextrin or adsorption on the surface of microcrystalline cellulose. Solid samples of the inclusion complex 2,3-naphthalimides/b-cyclodextrin show maximum for fluorescence emission significantly different to the observed in methanolic solution. Beside this, a clear effect on the alkyl chain length could be observed for these samples which is probably due to differences in probe location inside the cyclodextrin cavity. The constancy for fluorescence quantum yield and fluorescence lifetime for the imides 1 - 4 adsorbed on microcrystalline cellulose suggests that, independently of the polarity of the solvent used for sample preparation, the probe is preferentially located on the cellulose surface. An increase of fluorescence quantum yield and fluorescence lifetime for solid samples, when compared to the values obtained in solution for the different solvents employed in this study (acetonitrile, methanol and water), is fully in accordance with a decrease of the probe mobility due to inclusion in b-cyclodextrin or to adsorption on cellulose.

Keywords : b -cyclodextrin; naphthalimides; microcrystalline cellulose; diffuse reflectance; pulsed laser induced emission.

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