Oxygen Sensors Based On Fluorescence Quenching Of Ru-Dppz Complexes

In recent years, the discoveries of sensing materials and devices have become extremely important in environmental and biological fields. A remarkable development of luminescent chemosensing materials has already been made because of their high sensitivity and selectivity. Oxygen sensing material is usually composed of two parts, a support matrix and functional molecules of which the luminescent intensity is depended on the oxygen concentration. Oxygen molecule can quench the luminescence of the functional molecules through the pore of the matrix.Three diimine ruthenium complexes containing dppz as the second ligand [Ru(bpy)2(dppz)]2+,[Ru(phen)2(dppz)]2+ and [Ru(dphphen)2(dppz)]2+ have been synthesized and used in luminescent oxygen sensing study as sensing molecules. The fluorescent properties and the quenching intensity to molecular oxygen of those diimine ruthenium complexes are investigated. We assembled these complexes in different matrices to obtain the oxygen sensing system and did a comparative study between those systems.We fabricated two kinds of materials with oxygen sensing properties by incorporating [Ru(bpy)2(dppz)]2+ into MCM-41 and organically modified silicates (ormosil) sol-gel matrix. We did a comparative study between above two sensing materials in oxygen sensing performance. The results show that the oxygen sensing performance of oxygen sensing materials are influenced by the structure of supports. The oxygen sensing materials using ormosil as matrix have long-term stability and linear Stern-Volmer plot because the sensing molecules have the same microenvironment in ormosil matrix; the oxygen sensing performance of assemble systems are great enhanced using mesoporous molecular sieve as support duo to their high surface areas mesoporous molecular sieves and ordered pore structure.We obtained the oxygen sensing materials with high performance by assembling above three Ru-Dppz complexes into mesoporous molecular sieves MCM-41 and SBA-15 respectively. The Uv-vis spectra, fluorescent behaviors, oxygen sensing properties and the effect of pore size for oxygen materials were investigated. The experimental data show that luminescence of all assembly systems can be extremely quenched by molecular oxygen. The sensitivity of all multi-materials are more than 7, and [Ru(phen)2]dppz2+/ MCM-41 demonstrated the best performance, the sensitivity is 32.44, the quenching time is 2 s. The same luminescent sensing molecule, MCM-41-based composite materials demonstrate the higher performance than that of SBA-15-based in the same concentration. It is proved that the oxygen sensing properties of assembled systems are connected with the mesoporous and channel structure of the matrices.