title: Colorless, transparent, dye-doped polymer films exhibiting tunable luminescence color: controlling the dual-color luminescence of 2-(2'-hydroxyphenyl)imidazo[1,2-a]pyridine derivatives with the surrounding matrix.
abstract: Colorless, transparent, polymer films including 2-(2'-hydroxyphenyl)imidazo[1,2-a]pyridine (HPIP) derivatives, 1 and 2, are prepared by a spin-coating method. The observed emission spectra upon photoexcitation of these polymer films were composed of dual emission bands: the normal luminescence at 370-410 nm (purple) and the greatly Stokes-shifted emission at 520-580 nm (yellow) assigned as the excited-state intramolecular proton transfer (ESIPT) luminescence. Relative intensity of the two emissions varied according to the polymer matrices, resulting in change in the luminescent color of the dye-doped polymer films. Particularly, the luminescence properties of 6-cyano HPIP, 2, are highly susceptible to the surrounding environment, and therefore successfully tuned to produce a wide range of colors, from purple to orange, by changing its concentration within and the type of the polymer matrix. This observation can be ascribed to the formation of a relatively weak intramolecular hydrogen bond resulting from the electron-withdrawing 6-cyano group. Thus, we demonstrate large variations in emission color can be achieved using interactions of the single component with the surrounding matrix. These results offer promise as a convenient and effective method for a wide-range tuning the luminescence colors of dye-doped polymer films.
authors.affiliation: Department of Materials and Environmental Science, Institute of Industrial Science, the University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Furukawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shono
authors.forename: Toshiki
authors.initials: T
authors.lastname: Mutai
authors.forename: Koji
authors.initials: K
authors.lastname: Araki
keywords: ESIPT; dye-doped polymer; fluorescence; hydrogen bond; luminescence; transparent film