Wang Lei, Xiong Zuping, Zhi Sun Jing, Huang Feihe, Zhang Haoke, Zhong Tang Ben
MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310058, China.
Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 311215, China.
Angew Chem Int Ed Engl. 2024 Feb 19;63(8):e202318245. doi: 10.1002/anie.202318245. Epub 2024 Jan 16.
The length and mode of conjugation directly affect the molecular electronic structure, which has been extensively studied in through-bond conjugation (TBC) systems. Corresponding research greatly promotes the development of TBC-based luminophores. However, how the length and mode of through-space conjugation (TSC), one kind of weak interaction, influence the photophysical properties of non-conjugated luminophores remains a relatively unexplored field. Here, we unveil a non-linear relationship between TSC length and emission characteristics in non-conjugated systems, in contrast to the reported proportional correlation in TBC systems. More specifically, oligo(phenylene methylene)s (OPM[4]-OPM[7]) exhibit stronger TSC and prominent blue clusteroluminescence (CL) (≈440 nm) compared to shorter counterparts (OPM[2] and OPM[3]). OPM[6] demonstrates the highest solid-state quantum yield (40 %), emphasizing the importance of balancing flexibility and rigidity. Further theoretical calculations confirmed that CL of these oligo(phenylene methylene)s was determined by stable TSC derived from the inner rigid Diphenylmethane (DPM) segments within the oligomers instead of the outer ones. This discovery challenges previous assumptions and adds a new dimension to the understanding of TSC-based luminophores in non-conjugated systems.
共轭的长度和方式直接影响分子电子结构，这在通过键共轭（TBC）体系中已得到广泛研究。相应的研究极大地推动了基于TBC的发光体的发展。然而，作为一种弱相互作用的空间共轭（TSC）的长度和方式如何影响非共轭发光体的光物理性质，仍然是一个相对未被探索的领域。在此，我们揭示了非共轭体系中TSC长度与发射特性之间的非线性关系，这与报道的TBC体系中的比例相关性形成对比。更具体地说，与较短的同系物（OPM[2]和OPM[3]）相比，亚苯基甲烷低聚物（OPM[4]-OPM[7]）表现出更强的TSC和显著的蓝色聚集发光（CL）（≈440 nm）。OPM[6]表现出最高的固态量子产率（40%），强调了平衡柔韧性和刚性的重要性。进一步的理论计算证实，这些亚苯基甲烷低聚物的CL是由低聚物内部刚性二苯甲烷（DPM）片段而非外部片段产生的稳定TSC所决定的。这一发现挑战了先前的假设，并为理解非共轭体系中基于TSC的发光体增添了新的维度。
