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 dyedoped
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.