Rational design of dual-emissive luminescent materials plays an important role in ratiometric oxygen sensing. Fluorescent diflouroboron β-diketonates (BF<sub>2</sub>bdks) show two-photon absorption, strong emission, good photostability, and demonstrated utility for bioimaging applications. When coupled with biocompatible poly(lactic acid) (PLA), BF<sub>2</sub>bdks exhibit intense fluorescence and room temperature phosphorescence (RTP) in the solid state. These single component, biodegradable materials minimize dye heterogeneity and dye-matrix leaching and can be easily fabricated into nanoparticles suitable for cellular uptake and oxygen-sensing applications. For increased tissue penetration of light and multiplexing applications, red-shifted dyes with different emission wavelengths are desirable. To this end, a new series of thiophene-substituted model complexes were synthesized and luminescence was investigated in methylene chloride solution and dye/PLA blends. Under UV irradiation, all materials showed blue light absorbance and intense emission in air and under nitrogen. Also RTP (afterglow) was observed when UV excitation had ceased. By varying bdk donor ability (Me, Ph, PhOMe) and heavy atom substitution (Br, I) on the thiophene ring, red shifted RTP was achieved (RTP &gt; 600 nm). Promising model candidates inspired synthesis of dye- polymer conjugates made from hydroxyl-functionalized dye initiators via ring opening polymerization of DL-lactide. Additionally, nanoparticles were fabricated from these polymers to calibrate oxygen sensitivity. Synthesis, characterization and potential applications of these materials will be discussed.

Synthesis and dual-emissive properties of thiophene-substituted difluoroboron β-diketonates in poly(lactic acid)

249th National Meeting (2015)

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