Luminescent difluoroboron β-diketonate (BF<sub>2</sub>bdk) compounds exhibit many environment-sensitive properties, such as solvatochromism and viscochromism. In this study, a series of dimethylamino-substituted BF<sub>2</sub>bdk dyes were synthesized, and showed full-color emissions in 1,4-dioxane (from blue to red: D1–D5). Density functional theory (DFT) calculations displayed intramolecular charge transfer (ICT) from the dimethylamino-substituted phenyl ring to the difluoroboron moiety for all the dyes. Environment-sensitive properties for all the boron complexes were investigated in solution, including solvatochromism and viscochromism. All the dyes showed positive solvatochromism with bathochromic emission shifts in more polar solvents. In viscochromic studies, the dyes exhibited increased fluorescence intensity in more viscous media. Furthermore, lipid model studies were conducted to explore the sensing and probing properties of the boron dyes in lipid environments. Here, saturated lipids such as dipalmitoylphosphatidylcholine (DPPC) and unsaturated lipids such as dioleoylphosphatidylcholine (DOPC) were used, and lipid vesicles were prepared using the extrusion method. For all the dyes, the emission spectra of the dye lipid blends in phosphate buffer solution (pH 7.4) showed red-shifted emission when mixed with DOPC vesicles. In addition, different sized lipid vesicles were obtained and mixed with the dyes, and the emission spectra indicate the sensitivity of the dyes to vesicle size. Emission spectra of different dye/lipid ratios were also collected and analyzed.

Full-color luminescent dimethylamino-substituted difluoroboron β-diketonate complexes as environment-sensitive probes

2019 Fall National Meeting

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