DATA [1,6-Diazapyrene: A Well-Defined Small-Size Prototype System for Nitrogen-containing PAHs]

The quest for nitrogen-doped (N-doped) polycyclic aromatic hydrocarbons (PAHs) requires well-defined prototype systems to understand the relationship between the structure and the resulting photophysical and photochemical properties. To this end, a novel, simple, and small compound, 1,6-diazapyrene, was synthesized. In-depth analysis, employing optical spectroscopy and (time-dependent) density functional theory, (TD-)DFT, elucidates the optical excitations on the basis of MO symmetry, energy, and topology considerations; the study further unveils the photophysical and photochemical deactivation kinetics after photoexcitation, revealing extreme changes against pyrene as well as against the well-known 2,7-diazapyrene isomer. The high sensitivity of the aza-substitution position to generate such changes is considered as highly relevant for the targeted design of N-doped PAHs in general.对氮掺杂（nitrogen-doped, N-doped）多环芳烃（polycyclic aromatic hydrocarbons, PAHs）的研究亟需构建结构明确的原型体系，以厘清其分子结构与所得光物理、光化学性质之间的构效关系。为此，本研究合成了一种结构新颖、简洁小巧的化合物1,6-二氮杂芘。本研究采用光谱学与（含时）密度泛函理论[(time-dependent) density functional theory, (TD-)DFT]开展深入分析，基于分子轨道（molecular orbital, MO）的对称性、能量及拓扑学特征阐明了其光激发过程；此外还揭示了光激发后的光物理与光化学失活动力学，发现相较于芘以及经典的2,7-二氮杂芘异构体，该化合物的相关性质发生了显著变化。氮取代位点对这类性质变化的高度敏感性，总体而言对于氮掺杂多环芳烃的定向设计具有重要指导意义。