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

摘要

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 T-2 (pi, pi*) state was stabilized by the pi-stacking interactions of the phosphorescent group tynca(-), which contributed to enhancing their luminescence lifetimes. In contrast, when the pi-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 [T-1 (n, pi*), short lifetime] and green [T-2 (pi, pi*), 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.