Room-temperature phosphorescence of acenaphthene in aerated solutions in the presence of bromoalcohols and γ-cyclodextrin

The inclusional complexation between gamma-cyclodextrin and acenaphthene in aqueous solution was investigated by spectroscopic techniques. A 1:1 complex was detected and its formation constant was determined. After adding bromoalcohols such as 2,3-dibramopropane-1-ol or 2-bromoethanol both a decrease of the fluorescence and an enhancement of the room-temperature phosphorescence (RTP) of acenaphthene were observed. The RTP signals from acenaphthene included in gamma-cyclodextrin were optimized. The apparent formation constant of the ternary gamma-cyclodextrin-acenaphthene-2,3-dibromopropane-1-ol complex was determined from RTP data. On the other hand, the inclusion complex formed between gamma-cyclodextrin, acenaphthene and 2-bromoethanol was found to be very labile and its equilibrium constant could not be determined with accuracy. Large RTP signals were obtained in both ternary systems, even in the absence of sodium sulfite as deoxygenant agent. This fact would indicate that in these complexes the acenaphthene is protected from the action of quenchers such oxygen. (C) 1998 Elsevier Science B.V. All rights reserved.