The photophysical properties of a series of heteroatom substituted indoles are explored to identify chemical means to control their emissive activity. In particular, we consider impacts of changes in the conjugated backbone, where the C═N bonds of benzoxazoles are replaced by C═P bonds (benzoxaphospholes). The effects of extending the π-conjugation, incorporating various secondary heteroatoms (X–C═P), and enforcing planar rigidity are also examined. Our computational analysis explains the higher fluorescence efficiency observed with extended π-conjugation and highlights the importance of maintaining molecular planarity at both ground- and emissive-state geometries.

中文翻译：

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控制带有C═P键的杂环系统的发射活性

探索了一系列杂原子取代的吲哚的光物理性质，以鉴定控制其发射活性的化学方法。特别是，我们考虑了共轭骨架变化的影响，共轭骨架中的苯并恶唑的C═N键被C═P键（苯并恶唑）取代。还研究了扩展π共轭，结合各种次级杂原子（X–C═P）和增强平面刚度的效果。我们的计算分析解释了在扩展的π共轭下观察到的更高的荧光效率，并强调了在基态和发射态几何结构上保持分子平面性的重要性。