物理化学学报 >> 2020, Vol. 36 >> Issue (1): 1907078.doi: 10.3866/PKU.WHXB201907078

所属专题： 庆祝唐有祺院士百岁华诞专刊

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四卤化锰(Ⅱ)配合物的结构调控及力致发光性能

秦妍妍1,佘鹏飞1,郭颂1,黄晓萌1,刘淑娟1,赵强1,*(),黄维1,2,*()   

  1. 1 南京邮电大学信息材料与纳米技术研究院，有机电子与信息显示国家重点实验室培育基地，南京 210023
    2 西北工业大学柔性电子研究院，西安 710072
  • 收稿日期:2019-07-25 录用日期:2019-09-03 发布日期:2019-09-10
  • 通讯作者: 赵强,黄维 E-mail:iamqzhao@njupt.edu.cn;provost@nwpu.edu.cn
  • 基金资助:
    国家杰出青年科学基金(61825503);中国博士后科学基金(2018M642282);江苏省自然科学基金(BK20180760);江苏省博士后科研资助计划(2018K155C)

Structural Manipulation and Triboluminescence of Tetrahalomanganese(Ⅱ) Complexes

Yanyan Qin1,Pengfei She1,Song Guo1,Xiaomeng Huang1,Shujuan Liu1,Qiang Zhao1,*(),Wei Huang1,2,*()   

  1. 1 Institute of Advanced Materials, Key Laboratory for Organic Electronics and Information Displays, Nanjing University of Posts & Telecommunications, Nanjing 210023, P. R. China
    2 Shaanxi Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an 710072, P. R. China
  • Received:2019-07-25 Accepted:2019-09-03 Published:2019-09-10
  • Contact: Qiang Zhao,Wei Huang E-mail:iamqzhao@njupt.edu.cn;provost@nwpu.edu.cn
  • Supported by:
    the National Funds for Distinguished Young Scientists, China(61825503);the China Postdoctoral Science Foundation(2018M642282);the Natural Science Foundation of Jiangsu Province, China(BK20180760);the Jiangsu Planned Projects for Postdoctoral Research Funds, China(2018K155C)

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摘要：

力致发光是一种力刺激诱导的发光现象。由于其独特的发光方式，使得力致发光材料在结构损伤检测、压力传感、显示和安全标记等方面展现出了巨大的应用价值。目前已报道的力致发光材料大多基于无机材料体系，而有机力致发光材料体系相对较少，并且人们对其发光机理的认识仍不清晰。在本文中，我们发现锰(Ⅱ)配合物[BPP]2[MnBr4]具有力致发光特性，并在此基础上设计合成了一系列具有力致发光性质的四卤化锰(Ⅱ)配合物。改变有机阳离子配体或者卤素阴离子可对其光物理性质进行有效调控。固态下，这些锰(Ⅱ)配合物均显示出了较强的光致发光现象，同时表现出了明显的力致发光特性。晶体结构分析表明，分子内/分子间强的C-H…X (X = Br或Cl)相互作用对锰(Ⅱ)配合物的力致发光起到了至关重要的作用，它可在较大程度上降低由分子振动和旋转造成的能量损失。本工作将为力刺激响应型材料体系的拓展提供一定的参考价值。

关键词: 力致发光, 锰(Ⅱ)配合物, 绿光发射, 磷光, 分子内/分子间相互作用

Abstract:

Triboluminescence is a fascinating luminescence phenomenon induced by mechanical stimuli. Triboluminescent materials have potential applications in lighting, displays, and sensing, owing to their distinctive modes of light generation. However, organic triboluminescent materials are severely limited, and their luminescence mechanism remains unclear. Herein, we found that the luminescent manganese(Ⅱ) complex [BPP]2[MnBr4] displayed interesting triboluminescence performance. A series of green emissive tetrahalomanganese(Ⅱ) complexes was rationally designed and synthesized. The associated single crystal structures revealed that all complexes consisted of one [MnX4]2− (X = Br or Cl) ion and two organic cationic ligands per unit cell, with a tetrahedral geometrical symmetry around the Mn(Ⅱ) ion. In addition, the photophysical properties of tetrahalomanganese(Ⅱ) complexes were easily tuned by varying the organic ligands or halogen ions, which is beneficial for these organic-inorganic hybrid structures. Under UV light irradiation, all tetrahalomanganese(Ⅱ) complexes in the solid state exhibited bright green luminescence and a broad featureless emission band at 450–650 nm. The time-resolved photoluminescent decay curves demonstrated that the emission lifetimes of the prepared tetrahalomanganese(Ⅱ) complexes ranged from 260.5 μs to 1.95 ms, which was attributed to phosphorescence. The long-lived emission was mainly due to the spin-forbidden nature of the metal center d–d (4T1(G)→ 6A1) radiative transition. Thermogravimetric analysis was performed to examine the thermodynamic stabilities of the tetrahalomanganese(Ⅱ) complexes. The thermal stabilities of manganese(Ⅱ) complexes with P-based ligands were higher than those of the complexes containing N-based ligands. Upon applying a force to the crystals, the tetrahalomanganese(Ⅱ) complexes all exhibited prominent triboluminescence that could be observed by the naked eye in the dark. Systematic analysis of the crystals showed that the TL activities of the manganese(Ⅱ) complexes were related to the intra- and inter-molecular C-H···X (X = Br or Cl) interactions. The intra- and inter-molecular C-H···X interactions significantly reduced the possible energy loss caused by molecular vibrations and rotations in the [MnX4]2− unit under mechanical stress, improving TL emission. Moreover, a comparison of photoluminescence and triboluminescence indicated that different excitation sources yielded two distinct luminescence processes: transition of excitons excited by illumination and recombination of electrons and holes on the surface driven by polarization charges. Overall, the results presented herein new opportunities for fundamental research based on the developed class of triboluminescent materials.

Key words: Triboluminescence, Manganese(Ⅱ) complex, Green-light emission, Phosphorescence, Intra-/inter-molecular interaction