Photophysical properties of single bondRe(I)(CO)3(phen) pendants grafted to a poly-4-vinylpyridine backbone. A correlation between photophysical properties and morphological changes of the backbone

ALEJANDRA SAAVEDRA MONCADA; GUSTAVO T. RUIZ; EZEQUIEL WOLCAN; GUILLERMO J. FERRAUDI

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2016 vol. 321 p. 284 - 296

1010-6030

Photochemical and photophysical properties of a polymer, Re-P4VP, consisting of single bondRe(I)(CO)3(phen) pendants grafted to a poly-4-vinylpyridine backbone, P4VP, were interpreted on the bases of morphological transformations. These transformations are responsible of a significant increase of the MLCTRe(I)→phen excited state luminescence lifetime when the polymer concentration is increased. Also a nearly 8-fold increase in the luminescence quantum yield resulted from the protonation of Re-P4VP with consequent changes of the excited state decay kinetics. Results of TEM and AFM morphological studies on P4VP and Re-P4VP in the presence of HClO4 acid, i.e., to form Re-P4VPHnn+, revealed that they have concentration dependent morphologies. From low to large concentrations of the Re-P4VP polymer, the morphology of Re-P4VP varies from a nonhomogeneous distribution of spherical nanoaggregates coexisting with micrometer size fibers to an homogeneous distribution of spherical nanoaggregates with diameters around 25 nm. The Re-P4VP morphology is also altered when the polymer pyridines are protonated. Protonation of diluted solutions of Re-P4VP polymers decrease the sizes of the nanoaggregates and small objects with diameters smaller than 10 nm appear.