2-Methylnaphthalene (MN) exhibits MN excimer fluorescence in both beta-cyclodextrin (beta-CD) and gamma-cyclodextrin (gamma-CD) neutral aqueous solutions. beta-CD forms a 1:1 inclusion complex with MN, which self-associates to form a 2:2 inclusion complex emitting the MN excimer fluorescence. In 0.4 mol dm(-3) NaOH solutions, no excimer fluorescence has been observed, indicating that the 2:2 inclusion complex dissociates to two 1:1 inclusion complexes because of an electrostatic repulsion between the negatively charged hydroxy groups of the two beta-CD molecules contained in the 2:2 inclusion complex. For the gamma-CD-MN system as well as the beta-CD-MN system, the excimer fluorescence can be explained in terms of the formation of a 2:2 inclusion complex through a self-association of 1:1 inclusion complexes.
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[Anonymous], 1984, J INCLUSION PHENOM M, DOI DOI 10.1007/BF00662250