[Studies on the effects of steric hindrance of guest molecule on the formation of inclusion complexes by molecular luminescence].

Fluorescence and room temperature phosphoresce (CD-RTP) induced by cyclodextrin methods were employed to investigate the effects of steric hindrance of guest molecule on the formation of inclusion complexes of beta-cylcodextrin (beta-CD) and bromonaphthalene (BrN). It has been found that the RTP intensity of 2-BrN/beta-CD/n-Bu/ph was less than one third of that of 1-BrN/beta-CD/n-Bu/ph and fluorescence emission spectra of 2-BrN/beta-CD/n-Bu/ph had a red shift of 5-10 nm comparing with that of 1-BrN/beta-CD/n-Bu/ph under the optimum experimental conditions, respectively. These results exhibited that the steric locations of bromine in BrN strongly influenced the formation of inclusion complexes. The determination of the two quadri-inclusion complexes constants further demonstrated that the steric hindrance has a great effect on the formation of inclusion complexes. According to the above experimental results, the mechanism of formation of inclusion complexes were discussed briefly.