Peterson Eric, Maust Ruth L, Jasti Ramesh, Kertesz Miklos, Tovar John D
Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Department of Chemistry and Biochemistry, Materials Science Institute, and Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, Oregon 97403, United States.
J Am Chem Soc. 2022 Mar 16;144(10):4611-4622. doi: 10.1021/jacs.2c00419. Epub 2022 Mar 4.
In this report, we describe the synthesis and electronic properties of small-molecule and polymeric [8]cycloparaphenylenes ([8]CPPs) with disjointed pi-conjugated substituents. Arylene-ethynylene linkers were installed on opposite sides of the [8]CPP nanohoop as separated by three phenyl units on either side such that the monomer systems have (C symmetry) and (C symmetry) conformers with a small energy gap (0.1-0.6 kcal/mol). This disjoined substitution pattern necessarily forces delocalization through and around the CPP radial structure. We demonstrate new electronic states from this radial/linear mixing in both the small molecules and the pi extended polymers. Quantum chemical calculations reveal that these electronic processes arise from multiple operative radial/linear conjugation pathways, as the disjoint pattern results in both and connections to the CPP ring. These results affirm the unique nature of hybrid radial and linear pi electron delocalization operative in these new conjugation pathways.
在本报告中，我们描述了具有不连续π共轭取代基的小分子和聚合物[8]环对亚苯基（[8]CPPs）的合成及其电子性质。亚芳基乙炔连接基安装在[8]CPP纳米环的相对两侧，两侧各由三个苯基单元隔开，使得单体体系具有（C对称性）和（C对称性）构象异构体，且能隙较小（0.1 - 0.6千卡/摩尔）。这种不连续的取代模式必然会迫使电子离域穿过并围绕CPP的径向结构。我们在小分子和π扩展聚合物中均展示了这种径向/线性混合产生的新电子态。量子化学计算表明，这些电子过程源于多种有效的径向/线性共轭途径，因为这种不连续模式导致了与CPP环的和连接。这些结果证实了在这些新共轭途径中起作用的混合径向和线性π电子离域的独特性质。
