Artículos de revistas
Static and dynamic bimolecular fluorescence quenching of porphyrin dendrimers in solution
Fecha
2008Registro en:
JOURNAL OF FLUORESCENCE, v.18, n.5, p.821-826, 2008
1053-0509
10.1007/s10895-007-0309-7
Autor
MATOS, Mauricio S.
HOFKENS, Johan
GEHLEN, Marcelo H.
Institución
Resumen
The fluorescence quenching kinetics of two porphyrin dendrimer series (GnTPPH(2) and GnPZn) by different type of quenchers is reported. The microenvironment surrounding the core in GnPZn was probing by core-quencher interactions using benzimidazole. The dependence of quencher binding constant (K(a) ) on generation indicates the presence of a weak interaction between branches and the core of the porphyrin dendrimer. The similar free volume in dendrimers of third and fourth generation suggests that structural collapse in high generations occurs by packing of the dendrimer peripheral layer. Dynamic fluorescence quenching of the porphyrin core by 1,3-dicyanomethylene-2-methyl-2-pentyl-indan (PDCMI) in GnTPPH(2) is a distance dependent electron transfer process with an exponential attenuation factor beta=0.33 angstrom(-1). The quenching by 1,2-dibromobenzene occurs by diffusion process of the quencher toward to the porphyrin core, and its rate constant is practically independent of dendrimer generation.