Excited state vs. photoinduced charge separation in bundles of a polyamide containing

G. T. RUIZ; A.G. LAPPIN; G. FERRAUDI

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

Elsevier

Año: 2009 vol. 206 p. 1 - 9

1010-6030

A new polyimide containing pendent AlIIIphthalocyaninetetrasulfonate groups, [HOAlIII(pc)(SO3-)3(SO2N<)], was synthesized and the morphology of the polymer, poly(HOAlIIItspc), in aqueous solutions was investigated using transmision electron microscopy and UV-vis absorption and emision spectroscopies. The strands of poly(HOAlIIItspc) are associated in near spherical bundles with ~ 150 nm diameter in aqueous solutions. Most of the pendants in the bundles are forming p-stacks where the largest fraction of them must be dimers. Flash photochemical observations in a 0.15 ps to 100 ms time domain revealed the photogeneration of pendent radicals, [HOAlIII(pc•)(SO3-)3(SO2N<)]- and [HOAlIII(pc•)(SO3-)3(SO2N<)]-. This process stands in contrast with the photochemistry that AlIII tetrasulfonatedphthalocyanine shows under the same experimental conditions of poly(HOAlIIItspc). The kinetics of the phthalocyanine radicals formation and disappearance is consistent with energy and charge transfers between phthalocyanine pendants in the bundle. Radical scavengers (methylviologen, O2, cathecol, lignine) present in the solutions of poly(HOAlIIItspc) trapped the phthalocyanine radicals demonstrating that scavenging reactions can compete with the slow radical-radical annihilation process.