Department of Chemistry, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
J Phys Chem B. 2020 Nov 5;124(44):9921-9930. doi: 10.1021/acs.jpcb.0c07532. Epub 2020 Oct 21.
A series of azaperylene derivatives such as monoazaperylene (MAPery), 1,6-diazaperylene (1,6-DiAPery), 1,7-diazaperylene (1,7-DiAPery), 1,12-diazaperylene (1,12-DiAPery), triazaperylene (TriAPery), and tetraazaperylene (TetAPery) was synthesized by changing the position and number of nitrogen atoms at the bay region of a perylene skeleton in 1, 6, 7, and 12 positions. The density functional theory (DFT) calculations and electrochemical measurements suggested that the energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states significantly become stabilized with increasing the number of nitrogen atoms, whereas the estimated HOMO-LUMO gaps approximately remain constant. This result is in good agreement with the absorption and fluorescence spectral measurements. Additionally, these steady-state spectroscopic measurements demonstrate the broadened spectra as compared to pristine perylene (Pery). In photophysical measurements, the fluorescence quantum yields (Φ) significantly decreased as the number of nitrogen atoms increased, whereas much enhanced quantum yields and rate constants of internal conversion (Φ and ) were observed. Especially, the increased values of TriAPery (: ∼10 s) and TetAPery (: ∼10 s) are much larger than those of diazaperylene and monoazaperylene derivatives (: ∼10 s). These photophysical trends were successfully explained by time-dependent DFT (TD-DFT) calculations. Finally, the characteristic protonated and deprotonated processes of nitrogen atoms in azaperylenes under acidic conditions were monitored utilizing absorption and fluorescence measurements. The binding constants demonstrate that the nitrogen atoms at 1 and 12 positions of a perylene skeleton are essential for the increased values.
一系列氮杂并苯衍生物，如单氮杂并苯（MAPery）、1,6-二氮杂并苯（1,6-DiAPery）、1,7-二氮杂并苯（1,7-DiAPery）、1,12-二氮杂并苯（1,12-DiAPery）、三氮杂并苯（TriAPery）和四氮杂并苯（TetAPery），是通过改变并苯骨架中 1、6、7 和 12 位氮原子的位置和数量合成的。密度泛函理论（DFT）计算和电化学测量表明，最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能级的能量随着氮原子数量的增加而显著稳定，而估计的 HOMO-LUMO 能隙大致保持不变。这一结果与吸收和荧光光谱测量结果一致。此外，这些稳态光谱测量表明，与原始并苯（Pery）相比，这些衍生物的光谱拓宽。在光物理测量中，随着氮原子数量的增加，荧光量子产率（Φ）显著降低，而内部转换的量子产率和速率常数（Φ和）则大大提高。特别是，TriAPery（Φ：∼10 s）和 TetAPery（Φ：∼10 s）的增加值远远大于二氮杂并苯和单氮杂并苯衍生物（Φ：∼10 s）。这些光物理趋势通过时间相关的密度泛函理论（TD-DFT）计算得到了成功的解释。最后，利用吸收和荧光测量监测了酸性条件下氮杂并苯中氮原子的特征质子化和去质子化过程。结合常数表明，氮原子在并苯骨架的 1 和 12 位对于增加值是必不可少的。
