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Excited-State Dynamics of Pyrene Incorporated into Poly(substituted methylene)s: Effects of Dense Packing of Pyrenes on Excimer Formation
journal contribution
posted on 2018-07-13, 18:31 authored by Tomohisa Takaya, Tatsuya Oda, Yuki Shibazaki, Yumiko Hayashi, Hiroaki Shimomoto, Eiji Ihara, Yukihide Ishibashi, Tsuyoshi Asahi, Koichi IwataThe
excited-state dynamics of pyrene incorporated into poly(substituted
methylene)s is investigated by picosecond time-resolved fluorescence
spectroscopy and femtosecond time-resolved near-IR absorption spectroscopy
in the 900–1400 nm region. The pyrene rings in poly(substituted
methylene)s are photoexcited to the monomer excited state immediately
after UV irradiation, followed by prompt excimer formation with time
constants of a few picoseconds to a few hundred picoseconds. The excimer
formation in poly(substituted methylene)s proceeds with much shorter
time constants than that in pyrene-incorporated polyacrylates, vinyl
polymer counterparts with the same side-chain structures, indicating
the presence of stronger electronic interaction between the pyrene
rings in poly(substituted methylene)s. The effects of every methylene
substitution hold when each pyrene ring is connected to the polymer
backbone with a monomethylene linker, while the effects are observed
only weakly when a tetramethylene linker is employed. The results
demonstrate the effectiveness of every methylene substitution in the
prompt excimer formation of pyrene connected to the polymer backbone
either directly or with the monomethylene linker.