Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Chemistry. 2022 Sep 1;28(49):e202201398. doi: 10.1002/chem.202201398. Epub 2022 Jul 13.
The reaction of a cyclic alkyl(amino)carbene (CAAC)-stabilized thiazaborolo[5,4-d]thiazaborole (TzbTzb) with strong Brønsted acids, such as HCl, HOTf (Tf=O SCF ) and [H(OEt ) ][BAr ] (Ar =3,5-(CF ) C H ), results in the protonation of both TzbTzb nitrogen atoms. In each case X-ray crystallographic data show coordination of the counteranions (Cl , OTf , BAr ) or solvent molecules (OEt ) to the doubly protonated fused heterocycle via hydrogen-bonding interactions, the strength of which strongly influences the H NMR shift of the NH protons, enabling tuning of both the visible (yellow to red) and fluorescence (green to red) colors of these salts. DFT calculations reveal that the hydrogen bonding of the counteranion or solvent to the protonated nitrogen centers affects the intramolecular TzbTzb-to-CAAC charge transfer character involved in the S →S transition, ultimately enabling fine-tuning of their absorption and emission spectral features.
环状烷基（氨基）卡宾（CAAC）稳定的噻唑硼杂[5,4-d]噻唑硼杂（TzbTzb）与强布朗斯特酸（如 HCl、HOTf（Tf=OSCF ）和 [H(OEt)][BAr]（Ar=3,5-(CF) 2C 6H 3））反应，导致 TzbTzb 的两个氮原子都质子化。在每种情况下，X 射线晶体学数据表明，抗衡阴离子（Cl -、OTf -、BAr -）或溶剂分子（OEt ）通过氢键相互作用与双质子化的稠合杂环配位，其强度强烈影响 NH 质子的 1H NMR 位移，从而能够调节这些盐的颜色（从黄色到红色）和荧光（从绿色到红色）。DFT 计算表明，抗衡阴离子或溶剂与质子化氮中心的氢键影响涉及 S →S 跃迁的 TzbTzb 到 CAAC 电荷转移特性，最终能够精细调整它们的吸收和发射光谱特征。
