The effects of β-cyclodextrin (β-CD) complexation on the absorption and emission properties of
the non-steroidal anti-inflammatory drugs tolmetin (TM), diflunisal (DF), and fenbufen (FB) have been investigated.
The absorption spectra of all these compounds are only slightly affected by the addition of β-CD. In
contrast, the emission properties were markedly influenced by CD complexation and in a different manner
for the three compounds due to a differentiated sensitivity of the excited drugs to the microenvironment.
The complexes are all characterised by a 1: 1 stoichiometry and two different inclusion geometries for TM-
β-CD complexes have been observed. Induced circular dichroism (icd) is observed due to the interaction of
the compounds with the CD chiral cavity. The icd spectra are characterized by maxima well corresponding
to those of the absorption spectra. A nonlinear analysis of the dependence of the icd signal magnitude on
the CD concentration provided association constants values Kass=1400±100M−1, and 2600±150M−1 for TM, DF, and FB respectively.
