Kato Tomoki, Imoto Daiki, Yagi Akiko, Itami Kenichiro
Department of Chemistry, Graduate School of Science, Nagoya University Chikusa Nagoya 464-8602 Japan
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University Nagoya 464-8602 Japan.
Chem Sci. 2025 Sep 11. doi: 10.1039/d5sc04694g.
We report the unexpected discovery that non-emissive [6]cycloparaphenylene ([6]CPP) can be made fluorescent by multiple additions of simple methyl groups. Dodecamethyl[6]CPP (Me[6]CPP) was synthesized using a gold-based macrocyclization method and isolated as a pair of isomers (rotamers), both of which fluoresce at 510-540 nm. Experimental and theoretical investigations revealed that multiple methyl substitutions suppress rotation around the phenylene units, enabling the individual rotamers to be isolated and their interconversion to be studied. This simple yet significant "methyl effect" in CPPs not only enhances our basic understanding of stereoelectronic effects in CPPs, but should also facilitate the design and application of CPP-based materials in various fields.
我们报告了一项意外发现，即通过多次添加简单的甲基，可以使非发光的[6]环对亚苯基（[6]CPP）产生荧光。使用基于金的大环化方法合成了十二甲基[6]CPP（Me[6]CPP），并分离得到一对异构体（旋转异构体），二者均在510 - 540 nm处发出荧光。实验和理论研究表明，多个甲基取代抑制了亚苯基单元周围的旋转，使得各个旋转异构体能够被分离，并对它们之间的相互转化进行研究。CPPs中这种简单而重要的“甲基效应”不仅增强了我们对CPPs中立体电子效应的基本理解，而且还应有助于基于CPP的材料在各个领域的设计和应用。
