The formation of inclusion complexes of hydroxypropyl-bcyclodextrin,
heptakis(2,6-di-O-methyl)-b-cyclodextrin and
heptakis(2,3,6-tri-O-methyl)-b-cyclodextrin with 5,10,15,20-
tetrakis(4-pyridyl)porphyrin (TpyP) has been studied in
aqueous buffer solution (phosphate buffer pH 5 7 and I 5
0.01 M) to give a structural and spectroscopic characterization
of a new class of potential sensitizers for photodynamic
therapy. The interaction was investigated by a combination of
UV/Vis absorption, fluorescence anisotropy, time-resolved
fluorescence and circular dichroism. The experimental results
point to the presence of the pigment in water in a monomeric
complexed form. The fluorescence anisotropy measurements
suggest that TpyP forms 1:1 complexes with heptakis(2,3,6-tri-
O-methyl)-b-cyclodextrin and hydroxypropyl-b-cyclodextrin,
while 1:2 complexes are obtained with heptakis(2,6-di-Omethyl)-
b-cyclodextrin
