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

Abstract

Photophysical characteristics and emission based response of tris(2,2′-bipyridyl)ruthenium(II)chloride (Ru(bipy)32+) 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 O2 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 23nm in the emission wavelength and an enhanced Stoke's shift value of (Ru(bipy)32+) with respect to ionic liquid free sol–gel composites. The response and regeneration times were 5 and 10s after exposure to 100% O2 and 100% N2, respectively. The offered composite is only available for gas phase measurements.