Chong Hui, Fron Eduard, Liu Zhen, Boodts Stijn, Thomas Joice, Harvey Jeremy N, Hofkens Johan, Dehaen Wim, Van der Auweraer Mark, Smet Mario
Division of Polymer Chemistry and Materials, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
Division of Molecular Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
Chemistry. 2017 Apr 3;23(19):4687-4699. doi: 10.1002/chem.201700015. Epub 2017 Mar 15.
A novel palladium-catalyzed direct C(sp )-H arylation of the methyl group at the 8-position of BODIPY by bromoarenes was established. A deprotonative cross-coupling process was supposed to be involved in the reaction. This approach allowed us to attach electron-donating/withdrawing, halogen substituted aryls and a heteroaryl with a yield running from 55 to 99 %. Novel pH sensors, which in the absence of acid showed the occurrence of photoinduced electron transfer, were synthesized by attaching dimethylaniline to the methyl at the C8-position of BODIPY. The reference compounds with dimethylaniline directly attached to the C8-position were also synthesized and besides photoinduced electron transfer also showed a charge-transfer emission. Their photophysical properties were investigated by steady-state fluorescence, time-correlated single-photon counting and femtosecond fluorescence up-conversion. Time-dependent density functional (TD-DFT) electronic-structure calculations on the properties of the excited states corresponding to local excitation of the BODIPY core and to charge transfer were conducted. Upon addition of trifluoroacetic acid in toluene and ethanol, the partial fluorescence intensity recovery was at least an order of magnitude more efficient with the newly synthesized sensors compared to the traditional reference sensors. The improved sensitivity of these novel BODIPY-based pH sensors was attributed to less efficient proton-coupled electron transfer of the protonated species.
建立了一种新颖的钯催化溴代芳烃与BODIPY 8位甲基的直接C(sp) -H芳基化反应。该反应可能涉及去质子交叉偶联过程。这种方法使我们能够连接供电子/吸电子、卤素取代的芳基和杂芳基，产率在55%至99%之间。通过将二甲基苯胺连接到BODIPY的C8位甲基上，合成了新型pH传感器，在无酸条件下，这些传感器显示出光诱导电子转移现象。还合成了二甲基苯胺直接连接到C8位的参考化合物，它们除了光诱导电子转移外，还显示出电荷转移发射。通过稳态荧光、时间相关单光子计数和飞秒荧光上转换对它们的光物理性质进行了研究。对与BODIPY核心的局部激发和电荷转移相对应的激发态性质进行了含时密度泛函(TD-DFT)电子结构计算。在甲苯和乙醇中加入三氟乙酸后，与传统参考传感器相比，新合成的传感器的部分荧光强度恢复效率至少高出一个数量级。这些基于BODIPY的新型pH传感器灵敏度的提高归因于质子化物种的质子耦合电子转移效率较低。
