In this manuscript, we will illustrate a new idea for narrowing energy gaps between frontier molecular orbitals (FMOs) by selectively perturbing the levels of highest occupied molecular orbitals (HOMOs) and/or lowest unoccupied molecular orbitals (LUMOs). Initially, the basic concept of the isolated FMOs is explained by employing pentaazaphenalene (5AP) derivatives. It was found that electronic structures of the isolated LUMO of 5AP can be preserved even when incorporated into polymer chains if the connecting points are separated from the isolated LUMO. The mechanism and their unique electronic properties are summarized. Next, conversely, isolated HOMO and LUMO can be perturbed by conjugation effects independently. On the basis of this fact, near infrared (NIR)-absorbing molecules can be obtained by selectively elevating HOMO and lowering LUMO energy levels. We also mention strategies for enhancing luminescent properties of 5AP derivatives. Finally, we demonstrate that the isolated LUMO can be found in commodity luminescent dyes, such as boron dipyrromethene (BODIPY). By selectively lowering the LUMO energy level through the aza-substitution at the skeletal carbon where the isolated LUMO is distributed, NIR-emissive polymers can be obtained. Versatility of the isolated FMOs for obtaining optoelectronic organic materials is explained in this review.

中文翻译：

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通过一个前沿分子轨道的选择性摄动来缩小能隙的新思想

在本手稿中，我们将通过选择性地扰动最高占据分子轨道（HOMOs）和/或最低未占据分子轨道（LUMOs）的水平，来缩小前沿分子轨道（FMO）之间的能隙的新思想。最初，通过使用五氮杂萘（5AP）衍生物解释了分离的FMO的基本概念。已经发现，即使连接点与分离的LUMO分开，即使将5AP的分离的LUMO的电子结构结合到聚合物链中也可以保留。总结了其机理及其独特的电子性能。接下来，相反地，分离的HOMO和LUMO可以被共轭效应独立地扰动。基于这个事实，可以通过选择性地提高HOMO和降低LUMO能级来获得近红外（NIR）吸收分子。我们还提到了增强5AP衍生物发光性能的策略。最后，我们证明了分离出的LUMO可以在商品发光染料中发现，例如硼二吡咯亚甲基（BODIPY）。通过选择性地通过分布孤立LUMO的骨架碳上的氮杂取代来降低LUMO能级，可以获得NIR发射聚合物。这篇综述解释了分离的FMOs获得光电有机材料的多功能性。通过选择性地通过分布孤立LUMO的骨架碳上的氮杂取代来降低LUMO能级，可以获得NIR发射聚合物。这篇评论解释了分离的FMOs获得光电有机材料的多功能性。通过选择性地通过分布孤立LUMO的骨架碳上的氮杂取代来降低LUMO能级，可以获得NIR发射聚合物。这篇综述解释了分离的FMOs获得光电有机材料的多功能性。