Tetrakis(4-pyridyl)porphyrin supramolecular complexes with cyclodextrins in aqueous solution.
The formation of inclusion complexes of hydroxypropyl-beta-cyclodextrin, heptakis(2,6-di-O-methyl)-beta-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin with 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TpyP) has been studied in aqueous buffer solution (phosphate buffer pH = 7 and I = 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)-beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin, while 1:2 complexes are obtained with heptakis(2,6-di-O-methyl)-beta-cyclodextrin.
Cosma
Pinalysa
P
Dipartimento di Chimica, Università di Bari, Bari, Italy. p.cosma@chimica.uniba.it
Catucci
Lucia
L
Fini
Paola
P
Dentuto
Pasquale L
PL
Agostiano
Angela
A
Angelini
Nicola
N
Scolaro
Luigi Monsù
LM