Triboluminescent materials that generate emission of light in response to mechanical stimulus attract significant attention due to their applications in development of "smart materials" and damage sensors. Among metal complexes, rare-earth europium and terbium complexes are most widely used, while there is no systematic data on triboluminescence in more readily available and inexpensive Cu complexes, with only a few scattered examples reported in the literature. We report a new family of photoluminescent Cu-NHC complexes that show bright triboluminescence (TL) in crystal state visible even in ambient light under air upon grinding or crushing the crystalline sample. Moreover, when these complexes are dispersed into amorphous polymethylmethacrylate (PMMA) films even at small concentrations, TL is easily observed. In Cu-containing polymer films, surrounding gas discharge is likely involved in excitation of brightly luminescent Cu-NHC complexes. Observation of TL in polymer films overcomes limitations of using crystalline phase for mechanoresponse and opens up possibilities for development of mechanoresponsive coatings and materials based on inexpensive metals such as Cu.
产生光发射以响应机械刺激的
发光材料吸引了很大的关注,因为它们在“智能材料”和损伤传感器的开发中具有应用。在
金属配合物中,稀土
铕和
铽配合物被广泛使用,而在更易获得和廉价的
铜配合物中,尚无系统的触发发光数据,只有少数零星的例子报道在文献中。我们报告了一类新的具有明亮发光的
铜-氮杂环卡宾配合物家族,在晶体状态下,即使在空气下,通过研磨或压碎晶体样品也可以看到明亮的发光。此外,当这些配合物分散到无定形
聚甲基丙烯酸甲酯(P
MMA)薄膜中,即使在低浓度下,也很容易观察到发光。在含
铜聚合物薄膜中,周围气体放电可能参与激发明亮发光的
铜-氮杂环卡宾配合物。在聚合物薄膜中观察到发光克服了使用晶体相进行机械响应的限制,并为基于廉价
金属如
铜的机械响应涂层和材料的开发打开了可能性。