Thienyl Difluoroboron β-Diketonates in Solution and Polylactide Media

Ditluoroboron p-diketonates (BF,bdks) have impressive optical properties in both solution and the solid state. In particular, both fluorescence and room-temperature phosphorescence are present when the dyes are confined to a rigid matrix, such as poly(lactic acid) (PLA). To expand the current knowledge and colour range capabilities of this unique type of multi-emitting chromophore, a series of thienyl-substituted BF(2)bdk complexes have been synthesized. The photophysical properties were investigated in dichloromahane solution and in the solid state as dyc/PLA blends. By varying donor ability, i.e. methyl, phenyl, methoxy, and thienyl substituents, and by changing the dye loading in the PLA media (0.1-10 % dye loading) red-shifted emission was achieved, which is important for biological imaging applications. In dilute CH2Cl2 solution, complexes exhibited absorptions ranging from 350 to 420 nm, solid-state fluorescence in PLA ranging from 390 to 500 nm, and oxygen sensitive phosphorescence ranging from 540 to 585 nm in PLA blends. Promising candidates as dye/PLA blends serve as models for dye polymer conjugates for application as biological oxygen nanoprobes.