Computer simulation and spectroscopic study of inclusion complexes of cyclodextrins with luminescent porphyrins

Here we report a computational study of the structure, thermodynamic and spectroscopic properties of 1:1 and 2:1 inclusion complexes of luminescent porphyrins in β-cyclodextrin. Semiempirical PM6 (Parametric Method 6) calculation allowed the optimization of the structure of the complexes, showing that the inclusion in the CD cavity changes significantly the porphyrin ring planarity for the 2:1 complexes. Thermodynamic calculations evidenced that the inclusion complex formation is slightly endothermic and that it is a non-spontaneous process in the absence of water molecules. Finally the calculated spectra were found to be in very good agreement to previously reported experimental ones.