COMBO, ICPEES-UMR 7515, CNRS-Université de Strasbourg, 25 rue Becquerel, 67087, Strasbourg Cedex 02, France.
Laboratoire de Chimie Bioorganique et Médicinale, LIMA, UMR 7042, CNRS-Université de Strasbourg, 25 rue Becquerel, 67087, Strasbourg Cedex 02, France.
Chemistry. 2018 Aug 1;24(43):11119-11130. doi: 10.1002/chem.201801540. Epub 2018 Jul 3.
We describe here the synthesis of water-soluble red/NIR-emissive, boron-dipyrromethene (BODIPY) derivatives displaying optical (absorption and emission) responses in pH range of 4-8. Substitution close to the tertiary aniline or the phenol subunits selected as the proton-sensitive sites allowed us to finely tune the pH ranges. Furthermore, the introduction of sulfobetaine functions at the boron centre of these pH-responsive BODIPYs afforded valuable fluorescent dyes in the red/NIR region in aqueous media, for which the steric hindrance and electrostatic repulsions prevent their non-emissive aggregation. All the absorption and emission studies, as well as the protonation properties were investigated in aqueous, ethanolic and saline solutions (mimicking physiological conditions). Interestingly, the systems present a fluorescent ratiometric protonation response in EtOH, but the non-protonated form is almost a non-fluorescent species under quasi-physiological conditions (saline aqueous solutions) due to the fading of the emissive character of the low-lying charge-transfer transition in the presence of a supporting electrolyte.
我们在这里描述了水溶性红光/近红外发光的硼二吡咯甲川（BODIPY）衍生物的合成，这些衍生物在 pH 值为 4-8 的范围内显示出光学（吸收和发射）响应。靠近叔胺或苯酚取代基的取代被选为质子敏感位点，使我们能够精细地调整 pH 值范围。此外，在这些对 pH 敏感的 BODIPY 中引入磺酸甜菜碱官能团，在水相介质中提供了有价值的红光/近红外区域的荧光染料，其中空间位阻和静电斥力阻止了它们无辐射的聚集。所有的吸收和发射研究以及质子化性质都在水相、乙醇相和盐溶液（模拟生理条件）中进行了研究。有趣的是，这些体系在乙醇中呈现出荧光比率质子化响应，但在准生理条件（盐溶液）下，未质子化的形式几乎是一种非荧光物质，因为在存在支持电解质的情况下，低能电荷转移跃迁的发射特性会消失。
