Zhou Yichen, Huang Junxiang, Ghosh Animesh, Grimsdale Andrew C, Long Saran, Tao Qi, Gurzadyan Gagik G
School of Light Industry and Chemical Engineering, Dalian Polytechnic University, Dalian, 116024, China.
State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, China.
Chem Asian J. 2025 Sep;20(17):e00658. doi: 10.1002/asia.202500658. Epub 2025 Jun 20.
The photophysical properties and excited-state dynamics of the nonlinear heteroacene derivative DBP6 (bis-phenylethynyl-substituted dibenzophenanthroline) were systematically investigated through steady-state spectroscopy, time-resolved fluorescence measurements, and density functional theory (DFT) calculations. This study focuses on the competitive relaxation pathways after excitation to the lowest excited band of phenanthroline, that is, charge-transfer (CT), and intramolecular benzene excimer formation, which govern its dual-emission behavior. After excitation of the lowest excited band of dibenzophenanthroline, with λ= 500 nm DBP6 in DCM exhibits dominant excimer emission at 570 nm with a long-lived fluorescence lifetime of 12 ns. This emission is attributed to stable π-π interactions between side phenyl rings. In contrast, excitation λ= 440 nm leads, in addition to excimer formation, also to weak S emission at 480 nm (t = 0.34 ns). Higher-energy excitation λ< 370 nm reveals ultrafast CT state formation as an intermediate bridging S depopulation and excimer generation. Solvent polarity-dependent studies demonstrate a progressive red-shift in S emission (455 nm in toluene to 515 nm in ethanol) confirming CT state stabilization in polar environments. DFT simulations corroborate experimental results, predicting S emission at 495 nm. By varying excitation wavelength and solvent polarity, DBP6's dual emission can be tuned, highlighting its potential for ratiometric sensing, stable organic light-emitting diodes (OLEDs), and energy conversion systems. This work advances the understanding of nonlinear heteroacenes and provides a framework for designing optoelectronic materials with tailored excited-state interactions.
通过稳态光谱、时间分辨荧光测量和密度泛函理论（DFT）计算，系统地研究了非线性并苯衍生物DBP6（双苯乙炔基取代的二苯并菲咯啉）的光物理性质和激发态动力学。本研究聚焦于菲咯啉激发到最低激发带后的竞争弛豫途径，即电荷转移（CT）和分子内苯准分子形成，它们决定了其双发射行为。在二苯并菲咯啉的最低激发带激发后，在二氯甲烷中λ = 500 nm的DBP6在570 nm处表现出占主导地位的准分子发射，荧光寿命长达12 ns。这种发射归因于侧苯环之间稳定的π-π相互作用。相比之下，激发波长λ = 440 nm除了导致准分子形成外，还在480 nm处产生弱的S发射（t = 0.34 ns）。更高能量的激发λ < 370 nm揭示了超快CT态的形成，它是连接S态去极化和准分子产生的中间体。溶剂极性相关研究表明S发射有逐渐的红移（在甲苯中为455 nm，在乙醇中为515 nm），证实了极性环境中CT态的稳定。DFT模拟证实了实验结果，预测S发射在495 nm。通过改变激发波长和溶剂极性，可以调节DBP6的双发射，突出了其在比率传感、稳定有机发光二极管（OLED）和能量转换系统方面的潜力。这项工作推进了对非线性并苯的理解，并为设计具有定制激发态相互作用的光电子材料提供了框架。
