Enhanced photoemission of the complex Eu(III)/poly(4-vinyl pyridine)-pyridine photoproduct

Liquid pyridine and polymeric solutions of poly(4-vinyl pyridine)/pyridine/water doped with Europium exhibit a broad blue emission centered at 460 nm with low intensities emissions at 590 and 614 nm under excitation of 380 nm wavelength via a pyridine electronic state. Under excitation of 395 nm wavelength to the ⁵L₆ state effective quenching of Eu(III) ⁵D₀ emission in both cases was observed. The polymeric solution is a photosensitive material and becomes a gel under UV-irradiation. In a gel the longer-wavelength yellow-colored emission under excitation of 460-480 nm appears. The presence of Eu(III) significantly increases the intensity of this emission. The maximum of the peak position is blue shifted from 524 to 504 nm and its quantum efficiency is higher by a factor of five. We make a first effort to interpret the results.