Fiber-optic oxygen sensor based on the fluorescence quenching of tris (5-acrylamido, 1,10 phenanthroline) ruthenium chloride

Leaking of immobilized fluorescent indicators from the sensing matrix affect the stability of optochemical sensors and, therefore, presents a major problem in this field. When a polymer is used as a matrix support, a covalent bonding of the fluorescence indicator to the matrix eliminates the leaking problem. However, covalent bonding of the indicator to the support cannot be used as a general approach since it may modify the spectral properties of the indicator and its sensing response toward the analyte. This paper describes the synthesis of a modified ruthenium phenanthroline complex which is suitable for acryl co-polymerization with acrylamide. The newly synthesized dye, tris (5 acrylamido, 1,10 phenanthroline) ruthenium chloride, Ru(5-acrylamido-phen)3, maintains its full oxygen response with a slight decrease in its quantum yield for emission. Leaking measurements show a significant improvement in the stability of fiber-optic oxygen sensors that use Ru(5-acrylamido-phen)3 as an oxygen sensitive fluorescence indicator, over previous fiber-optic oxygen sensors that make use of other ruthenium diimine complexes for oxygen measurement. The improvement in stability is particularly noticeable in samples of increased hydrophobicity.