Independently Tuned Frontier Orbital Energy Levels of 1,3,4,6,9b-Pentaazaphenalene Derivatives by the Conjugation Effect
Independently Tuned Frontier Orbital Energy Levels of 1,3,4,6,9b-Pentaazaphenalene Derivatives by the Conjugation Effect
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DOI：
10.1021/acs.joc.8b03161
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发表时间：
2019-03-01
影响因子：
3.6
通讯作者：
Chujo, Yoshiki
中科院分区：
文献类型：
--
作者：
Watanabe, Hiroyuki;Tanaka, Kazuo;Chujo, Yoshiki
本文报道了1,3,4,6,9b-五氮杂烯（5AP）衍生物的合成及其独特的取代基效应。我们通过（N，N-吡啶-2,6-二酰基）双酰胺开发了新的合成路线，使我们能够制备各种取代的5ap，并利用紫外-可见吸收光谱、循环伏安法和密度泛函理论计算系统地研究取代对多N-杂环5ap电子结构的影响。从分析中，我们发现取代基对5APs电子态的影响随着取代位置的不同而显著变化。结果表明，取代基的共轭效应通过改变5AP环上的取代位置特异性地表达为最高占据分子轨道（HOMOs）或最低未占据分子轨道（LUMOs）。因此，只有通过提高homo或降低lumo才能实现较小的HOMO-LUMO间隙。5AP固有分离的HOMO和LUMO是这种独特取代基效应的起源。这些结果表明，HOMOs和LUMOs可以通过5APs中的共轭效应独立调节。这种前沿轨道的选择性可调性是有机分子作为现代光电器件和先进有机电子材料的应用所需要的特性。
Herein reported are syntheses and the unique substituent effect in 1,3,4,6,9b-pentaazaphenalene (5AP) derivatives. We developed the new synthetic route via (N,N-pyridine-2,6-diyl)bisamides, which enabled us to prepare a variety of substituted 5APs and to systematically investigate the substituent effects on the electronic structures of the multi-N-heterocyclic 5APs using UV-vis absorption spectroscopy, cyclic voltammetry, and density functional theory calculations. From the analyses, we found that the substituent effects regarding the electronic states of 5APs drastically varied depending on the substitution position. It was revealed that the conjugation effects from the substituents were specifically expressed either highest occupied molecular orbitals (HOMOs) or lowest unoccupied molecular orbitals (LUMOs) by altering the substitution position at the 5AP ring. As a result, small HOMO-LUMO gaps were accomplished only by elevating HOMOs or by lowering LUMOs. The intrinsically separated HOMO and LUMO of 5AP are the origin of this unique substituent effect. These results suggested that HOMOs and LUMOs can be independently tuned by the conjugation effects in 5APs. This selective tunability of either frontier orbital is a desired character for application of organic molecules as modern optoelectronic devices and advanced organic electronic materials.