Fluorescent Sensing Of Water Content In Organic Solvent By An Organic-inorganic Hybrid Film Based On [Ru（Bpy）₃]²⁺

Water in organic solvents usually has a great influence on organic chemical reactions, which can even determine product yield and selectivity of the reaction. Determination of water content in organic solvents is a very important issue, and it is one of most commonly encountered analytical points. Water molecule is not fluorescent itself, so that fluorescence detection of water cannot be carried out directly. It is known that fluorescence of a number of ruthenium complexes are very sensitive to water content. Thus, these complexs are expected to be used as water probes. Given that the ruthenium complexs are soluble only in water, some matrix is needed to carrier the water probes to sense water, while the matrix can absorb water or admit the penetration of water molecules to the probes.Organics-inorganic hybrid materials provide a good substrate for the fluorescent sensor of water, because hybrid materials can possess advantages of organic materials and inorganic materials. Organic compositions in the film can absorb water molecules, while inorganic compositions can immobilize fluorescent indicator through electrostatic attraction.In this paper, ruthenium complexes are adopted as fluorescence sensing indicator, silica and polyurethane (PU) hybrid organic-inorganic composite film as a substrate, and scratch method is used to prepare a water-sensitive film. The film has not only ideal flexibility and transparency, but also stability against water, acetone and tetrahydrofuran. What’s more, the film can response to the water content in acetone and tetrahydrofuran by fluorescence. Therefore, the water content sensing films can effectively response to water content in some of organic solvents with fluorescence detection. The main contributions as listed as follows:1.[Ru(bpy)3]2+energy level structure and fluorescence properties were summarized, the relationship between ruthenium complexes’fluorescence intensity and water content was analyzed, and precautions in the detection of water content were given.2. The organic-inorganic hybrid sensing film was prepared by sol-gel method. In order to improve fluorescence response of the sensing film, optimization of the organic-inorganic hybrid film is performed.3. Chemical bond structure of the sensing film and its internal structure were characterized by infrared spectroscopy and scanning electron microscopy. The relationship between ruthenium complexes and sensing film was researched by the absorption spectra and excitation spectrum; and the response of the film to water content was studied by both steady-state fluorescence spectra and dynamic spectra.