Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
Chem Commun (Camb). 2018 Jul 26;54(61):8490-8493. doi: 10.1039/c8cc04916e.
We report the visible-light circular dichroism (CD) of colourless organic compounds based on interfacial charge-transfer (ICT) transitions with TiO2 nanoparticles. We employed three kinds of colourless chiral compounds, l-ascorbic acid, d-ascorbic acid, and l-noradrenaline. These compounds showed a broad ICT band in the visible region between 400 and 600 nm upon their chemisorption on TiO2 nanoparticles. l-Ascorbic acid and l-noradrenaline adsorbed on the TiO2 nanoparticles showed positive and negative CD signals in the visible region, respectively. d-Ascorbic acid, which is the enantiomer of l-ascorbic acid, exhibited positive CD signals in the visible region, but different g factors (Δε/ε) from those of TiO2-l-ascorbic acid, well reflecting the different chirality of the substituent group. The visible-light CD based on ICT transitions enables selective visible-light CD sensing and imaging of colourless chiral biomolecules even if coexisting with other colourless chiral compounds such as proteins and DNA. Furthermore, the molecular dependence of the g factor allows us to identify chiral molecules.
我们报告了基于 TiO2 纳米粒子界面电荷转移（ICT）跃迁的无色有机化合物的可见圆二色性（CD）。我们采用了三种无色手性化合物，L-抗坏血酸、D-抗坏血酸和 L-去甲肾上腺素。这些化合物在化学吸附到 TiO2 纳米粒子上后，在 400 至 600nm 的可见光区域显示出宽 ICT 带。L-抗坏血酸和 L-去甲肾上腺素在可见光区域分别表现出正和负的 CD 信号。D-抗坏血酸，它是 L-抗坏血酸的对映体，在可见光区域表现出正的 CD 信号，但与 TiO2-L-抗坏血酸的 g 因子（Δε/ε）不同，很好地反映了取代基的不同手性。基于 ICT 跃迁的可见光 CD 能够选择性地对无色手性生物分子进行可见光 CD 传感和成像，即使与其他无色手性化合物如蛋白质和 DNA 共存也是如此。此外，g 因子的分子依赖性允许我们识别手性分子。
