Fluorescence and Phosphorescence Properties of Naphthalene in Aqueous D-Glucose Solutions Containing 6-Deoxy-6-iodo-β-cyclodextrin at Room Temperature

Abstract In aqueous solutions, 6-deoxy-6-iodo-β-cyclodextrin (β-CDI) forms a 1 : 1 inclusion complex with naphthalene. The naphthalene fluorescence is quenched upon the formation of the inclusion complex with β-CDI. The room-temperature phosphorescence of naphthalene has been observed from aqueous naphthalene solutions containing both d-glucose and β-CDI. Although the room-temperature phosphorescence has also been observed from aqueous naphthalene solutions containing both d-glucose (5.0 g/5.0 mL) and β-cyclodextrin (1.0 × 10−2 mol dm−3), its intensity amounts to at most 9% of that containing d-glucose (5.0 g/5.0 mL) and β-CDI (1.0 × 10−3mol dm−3). In addition to the high viscosities of d-glucose solutions, the external heavy atom effects of β-CDI cause the appearance of the room-temperature phosphorescence. The room-temperature phosphorescence quantum yield of naphthalene in d-glucose (5.0 g/5.0 mL) solution containing β-CDI (1.0 × 10−3 mol dm−3) has been estimated to be 2.2 × 10−3, which is around 1.8% of the intrinsic phosphorescence quantum yield of naphthalene in ethanol at 77 K.