Sensing water in organic solvent using a polyurethane-silica hybrid membrane doped with a luminescent ruthenium complex

摘要

We have prepared an ～1.4 μm thin hybrid film from polyurethane (PU) hydrogel and tetraethylorthosilicate (TEOS) by a sol-gel method, and have incorporated the red-luminescent ruthenium-tris-bipyridyl complex. At an optimized ratio of PU/TEOS (1.5:1; w/w) and annealing temperature (60 °C), the membrane sensor exhibits good capability to extract water from organic solvents but also can well retain the ruthenium dye. If contacted with water-containing organic solvents such as acetone or THF, both the luminescence intensity and wavelength change significantly. The response of luminescence intensity to the water fraction in organics is sigmoidal, which can be well fitted with a modified Stern-Volmer equation. The sensor works in the ranges of 0-6 % and 0-12 % (v/v) of water in acetone and THF, respectively, with detection limits of 0.13 % and 0.486 % (v/v).