STEADY-STATE FLUORESCENCE STUDIES OF THE COMPLEXES BETWEEN PYRENE ANDPER-6-O-TERT-BUTYLDIMETHYLSILYL ALPHA-CYCLODEXTRINS, BETA-CYCLODEXTRINS AND GAMMA-CYCLODEXTRINS

The complexation of pyrene by alpha-, beta- and gamma-cyclodextrins (C Ds), persubstituted at the 6 position by tert-butyldimethylsilyl group s, has been investigated using steady state fluorescence spectroscopy, The alpha-CD derivative does not, as would be expected from steric con siderations, form complexes. The beta- and gamma-CD derivatives form 1 :1 host-guest complexes which show high association constants in 90:10 H2O-DMF solution [i.e. beta-CD(SiR)(7), 4.85 x 10(5) M(-1); gamma-CD( SiR)(8), 4.91 x 10(5) M(-1)]. Analysis of the polarity of the microenv ironment by means of the I/III peak ratios shows a more polar cavity i n the case of gamma-CD(SiR)(8). The concentration dependence of I/III suggests that a weak supramolecular complex gamma-CD(SiR)(8)-pyrene-n . DMF, may exist.