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.
Tetrakis(4-pyridyl)phorphyrin supramolecular complexes with cyclodextrins in aqueous solution
CATUCCI, Lucia;AGOSTIANO, Angela;
2006-01-01
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
