Poly[methyl(phenyl)silanediyl] modified with dansyl fluorophore: Synthesis and photophysics

The syntheses and photophysical properties of novel luminescent polysilanes modified with dansyl fluorophores on various spacer (PMPSi‐n‐DNS) are reported. The modified polysilanes were prepared by condensation reaction of dansyl amines, such as 5‐(dimethylamino)naphthalene‐1‐sulfonohydrazide or N‐(ω‐aminoalkyl)‐5‐(dimethylamino)naphthalene‐1‐sulfonamides with formylated polymethyl(phenyl)silanediyl], yielding Schiff bases. The aldehyde groups were incorporated into the parent polymer by a one‐step reaction with dichloromethyl methyl ether in the presence of Lewis acid. Influence of the alkyl chain length (n) on the photophysical properties was investigated using absorption, steady‐state, and time‐resolved photoluminescence (PL) spectroscopy. The excitation energy transfer from the polysilane backbone to dansyl fluorophore was proved. PL decay dynamics revealed the existence of more than one excited species. In solution, the decay curves of PMPSi‐DNS (no spacer) were double exponential, whereas for PMPSi‐n‐DNS (with spacer), and, in thin films, the decays were three‐exponential. Polymer light‐emitting devices (LEDs) were prepared from the blends of modified polysilane with electroluminescent polymer poly2,5‐dimethoxy‐1,4‐phenylene‐1,2‐ethenylene‐2‐methoxy‐5‐(2‐ethylhexyloxy)‐(1,4‐phenylene‐1,2‐ethenylene)] (M3EH‐PPV). Compared with LED made of neat electroluminescent polymer, a significant performance improvement of blend LEDs was demonstrated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011