Ratiometic sensing is a useful method for quantifying oxygen in biological systems. Typically, ratiometric sensing materials combine a fluorescent reference dye and an oxygen sensitive metal-complex phosphor embedded in a polymer matrix. Single component, dual-emissive difluoroboron �-dibenzoylmethane-poly(lactic acid) (BF2dbmPLA) materials, in contrast, incorporate all of these features in one macromolecular material. When fabricated as nanoparticles, heavy atom substituted luminescent boron polymers have been successfully employed in tumor hypoxia, brain, and wound imaging with excellent spatial and temporal resolution. Intense emission, photostability, and two photon-absorbing properties make these materials attractive for imaging applications. To further optimize difluoroboron �-diketonate dyes for biomedical imaging applications, to enable multiplexing, and greater tissue penetration of light, it is advantageous to develop materials with red-shifted emission. One way to achieve this is by increasing the p-conjugation of the �-diketonate ligand. To this end, a series of naphthyl-substituted dyes was synthesized. Building on results from previous studies modulating phosphorescence with heavy atom placement and polymer molecular weight, effects of bromide location in these new naphthyl-phenyl and dinaphthyl dye polymer conjugates were investigated. Luminescence properties of these materials were studied in CH2Cl2 solution and as polymer films and computational studies of dyes were performed. The effects of extended conjugation, bromide heavy atom substitution, and polymer molecular weight on fluorescence and phosphorescence wavelengths and relative intensities will be discussed.

Effects of heavy atom placement and polymer molecular weight on dual emissive difluoroboron naphthyl �-diketonate polylactide materials

247th National Meeting (2014)

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