Yamada Hiroko, Hayashi Hironobu
Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
Photochem Photobiol Sci. 2022 Aug;21(8):1511-1532. doi: 10.1007/s43630-022-00235-x. Epub 2022 Jun 7.
Acenes, which are hydrocarbons comprising linearly fused benzene rings, have attracted considerable attention owing to their electronic structures and utility as organic electronic materials. However, the ease with which oligoacenes undergo oxidation increases with the number of linearly fused benzene rings owing to the increased energy of the highest occupied molecular orbital. The synthesis of naked oligoacenes with seven or more benzene rings is difficult because their open-shell structure renders them unstable. The recent development of a precursor method has enabled the in situ synthesis of oligoacenes under specific conditions and the spectroscopic observation of oligoacene in single crystals, in film matrices and under cryogenic conditions. Scanning tunneling microscopy and non-contact atomic force microscopy under ultra-high vacuum conditions have also made significant advances in the study of oligoacenes and oligoazaacenes. This paper reviews the recent progress in the synthesis of oligoacenes using precursors, with a particular focus on the chemical structures, synthesis, and reactivity of the precursors. The electronic properties of oligoacenes are also discussed in relation to the number of fused benzene rings, including their energy levels and spin states. These results will contribute to the synthesis and development of carbon nanomaterials with applications in the field of organic electronics.
并苯是由线性稠合苯环组成的碳氢化合物，因其电子结构以及作为有机电子材料的用途而备受关注。然而，由于最高占据分子轨道能量的增加，低聚并苯发生氧化的难易程度会随着线性稠合苯环数量的增加而提高。具有七个或更多苯环的裸低聚并苯的合成很困难，因为它们的开壳层结构使其不稳定。前驱体方法的最新发展使得在特定条件下原位合成低聚并苯以及对单晶、薄膜基质和低温条件下的低聚并苯进行光谱观察成为可能。在超高真空条件下的扫描隧道显微镜和非接触原子力显微镜在低聚并苯和低聚氮杂并苯的研究方面也取得了重大进展。本文综述了使用前驱体合成低聚并苯的最新进展，特别关注前驱体的化学结构、合成和反应性。还讨论了低聚并苯的电子性质与稠合苯环数量的关系，包括它们的能级和自旋态。这些结果将有助于有机电子领域应用的碳纳米材料的合成与开发。
