Room-temperature phosphorescence of 6-bromo-2-naphthol included in beta-cyclodextrin in the presence of cyclohexane.
The formation constant for a 1:1 binary complex between 6-bromo-2-naphthol (6B2N) and beta-cyclodextrin (CD) in aqueous solution was determined by both absorptimetric and fluorimetric methods. Room-temperature phosphorescence (RTP) was induced by adding small amounts of different apolar liquids as the third component, with cyclohexane producing the strongest enhancement effect. Microcrystals formed in the ternary system seem to be necessary for obtaining phosphorescence emission. The deoxygenation by flowing nitrogen does not improve the RTP signals, while the addition of sodium sulfite as chemical deoxygenant produces quenching of the signals. The calibration graph for 6-bromo-2-naphthol in the presence of beta-CD and cyclohexane was linear for the range of concentrations between 0.04 and 1 mug ml(-1), with a detection limit of 0.04 mug ml(-1).
Escandar
G M
GM
Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
Boldrini
M A
MA