Described here are the synthesis and photophysical and photochemical characterization of osmium complexes including [Os(bpy)2(sulf-dpp)]Cl2, [Os(phen)2(sulf-dpp)]Cl2, [Os(dpp)2(sulf-dpp)]Cl2, and [Os(CO)2Cl2(sulf-dpp)] where bpy is 2,2'-bipyridine, phen is 1,10-phenanthroline, dpp is 4,7-diphenyl-1,10-phenanthroline, and sulf-dpp is sulfonated 4,7-diphenyl-1,10-phenanthroline. The complexes are investigated for potential use in luminescence-based, hydrogel-supported sensors designed to measure analytes of clinical and environmental significance.  The analyte sensing approach requires an environment-sensitive luminophore embedded within a �smart� hydrogel that swells and contracts in response to the binding of analyte.  Upon swelling of the hydrogel, the luminophore experiences a change in local environment which can be detected through changes in luminescence intensity, maximum emission wavelength, and fluorescence anisotropy.  Osmium complexes are of particular interest because they are photochemically robust and have long excited state lifetimes and reasonable quantum yields, thus making them relatively easy to measure.  In addition, longer wavelength absorptions and emissions allow for inexpensive excitation and minimize interferences from autofluorescence in clinical samples.  Results are reported for the homologous series of osmium complexes measured in solvents of varying viscosity, and apparent trends are rationalized based on differences in dipole moment, size, and extent of conjugation.  The most promising environment-sensitive osmium complexes are identified, and recommendations are made for the rational design of improved luminophores.

Synthesis and characterization of osmium complexes for use in luminescence-based, hydrogel-supported sensors

247th National Meeting (2014)

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