Eight Cd(ii) coordination polymers with persistent room-temperature phosphorescence: intriguing dual emission and time-resolved afterglow modulation

• Published in: Inorganic chemistry frontiers 2020-02, Vol.7 (3), p.777-785
• Main Authors: Li, Yajie, Gai, Tianyu, Lin, Yuejin, Zhang, Wenjing, Li, Kai, Liu, Yan, Duan, Yanquan, Li, Baojun, Ding, Jie, Li, Jinpeng
• Format: Article
• Language: English
• Subjects: Coordination polymers; Crystallography; Encryption; Inorganic chemistry; Logos; Modulation; New technology; Optical properties; Phosphorescence; Room temperature; Stacking; Ultraviolet radiation
• ISSN: 2052-1545; 2052-1553
• DOI: 10.1039/c9qi01273g

In this work, a new series of coordination polymers (CPs) 1–8 were designed and successfully synthesized; they displayed typical afterglow at room temperature under ambient conditions. In 1–4, single green phosphorescence was observed, where the T2 (π, π*) state was stabilized by the π-stacking interactions of the phosphorescent group tynca−, which contributed to enhancing their luminescence lifetimes. In contrast, when the π-stacking interaction of the phosphorescent group tynca− was absent in the rigid matrix, 5–8 exhibited an intriguing time-resolved afterglow modulation, in which yellow [T1 (n, π*), short lifetime] and green [T2 (π, π*), long lifetime] phosphorescences were sequentially observed during the decay process when the common UV light was turned off. As one of the representatives of long-lived dual phosphorescent CPs, the promising optical properties of 8 allowed it to be used in logos for advanced anti-counterfeiting systems. To the best of our knowledge, this special and rare afterglow modulation has not been reported in the literature for persistent RTP (p-RTP) CP systems, and further exploration in this area may open a new door for newly emerging technologies such as optical recording and encryption or multimodal bio-imaging.