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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 16, Number 10
BKCSDE 16(10)
October 20, 1995 

Twisted Intramolecular Charge-Transfer Behavior of a Pre-Twisted Molecule, 4-Biphenylcarboxylate Bonded to Poly(Methyl Methacrylate)
Seong Gwan Kang, Kyo Duck Ahn, Dae Won Cho, Minjoong Yoon*
A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.
972 - 976
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