Photophysical and optical oxygen sensing properties of tris(bipyridine)ruthenium(II) in ionic liquid modified sol-gel matrix

Photophysical characteristics and emission based response of tris(2,2'-bipyridyl)ruthenium(II)chloride (Ru(bipy)(3)(2+)) to gaseous oxygen was investigated in ionic liquid modified sol-gel matrix. The ionic liquid; 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) was used for the first time in acid-catalyzed tetraethyl orthosilicate (TEOS) based sol-gel matrix. Effects of the ionic liquid to the oxygen sensitivity and to surface characteristics were examined. EMIMBF4 doped sol-gel slides exhibited enhanced O-2 sensitivity, larger Stern-Volmer constants, linear Stern-Volmer plots with respect to classical acid catalyzed sol-gel monoliths and completely crack-free surfaces. The utilization of EMIMBF4 in sol-gel matrix also caused a red shift of 23 nm in the emission wavelength and an enhanced Stoke's shift value of (Ru(bipy)(3)(2+)) with respect to ionic liquid free sol-gel composites. The response and regeneration times were 5 and 10 s after exposure to 100% O-2 and 100% N-2, respectively. The offered composite is only available for gas phase measurements. (C) 2008 Elsevier B.V. All rights reserved.