Department of Chemistry, University of Virginia , Charlottesville, Virginia 22904, United States.
ACS Appl Mater Interfaces. 2017 Sep 20;9(37):32008-32017. doi: 10.1021/acsami.7b06910. Epub 2017 Sep 6.
The optical properties of meta-alkoxy-substituted difluoroboron dibenzoylmethane dyes were investigated in solution and in the solid state. Meta-alkoxy substitution induced strong intramolecular charge transfer (ICT) from the oxygen-donating substituent to the halide and boron acceptors in the excited state, as compared to the π-π* transition that is observed with para-alkoxy substitution. The optical properties of para- and meta-substituted alkoxy boron dyes were evaluated by calculations, in dilute solution, and in solid-state films. When embedded in amorphous matrixes (e.g., PLA, PMMA, PS, cholesterol), all dyes showed fluorescence (F) and phosphorescence (P) emission. In this report, we show that meta-substitution resulted in enhanced solvatochromism and an increased phosphorescence-to-fluorescence ratio in solid-state films compared to analogous para-substituted samples. With enhanced phosphorescence intensity via the heavy-atom effect, iodo-substituted dyes were further studied in PLA-PEG nanoparticles. Oxygen calibrations revealed stronger phosphorescence and a greater oxygen-sensing range for the meta- versus para-alkoxy-substituted dyes, features that are important for oxygen-sensing materials design.
间烷氧基取代二氟硼二苯甲酰甲烷染料的光学性质在溶液中和固态中进行了研究。与对位烷氧基取代的π-π*跃迁相比，间烷氧基取代在激发态下诱导了从给电子取代基到卤化物和硼受体的强烈分子内电荷转移（ICT）。通过计算、稀溶液和固态薄膜评估了对位和间位取代烷氧基硼染料的光学性质。当嵌入非晶基质（例如 PLA、PMMA、PS、胆固醇）中时，所有染料都显示出荧光（F）和磷光（P）发射。在本报告中，我们表明与类似的对位取代样品相比，间位取代导致固态薄膜中溶剂化变色增强和磷光与荧光的比例增加。通过重原子效应增强磷光强度，碘取代染料在 PLA-PEG 纳米粒子中进一步研究。氧校准表明，间烷氧基取代的染料具有比对位烷氧基取代的染料更强的磷光和更大的氧感应范围，这些特性对于氧感应材料设计很重要。
