Bhatia Harsh, Dey Suvendu, Ray Debdas
Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar University, NH-91, Tehsil Dadri, Gautam Buddha Nagar 201314, Uttar Pradesh, India.
ACS Omega. 2021 Jan 28;6(5):3858-3865. doi: 10.1021/acsomega.0c05666. eCollection 2021 Feb 9.
Organic room-temperature phosphorescence (RTP) materials with persistent RTP (PRTP) have attracted huge interest in inks, bioimaging, and photodynamic therapy. However, the design principle to increase the lifetime of organic molecules is underdeveloped. Herein, we show donor(D)-acceptor(A) molecules (, , , and ) with similar orientation of donor rings in aggregates that cause a large number of noncovalent interactions. We observed that , , and showed PRTP, whereas showed only phosphorescence emission (Φ = ∼11%) with no PRTP property at ambient conditions. The spectroscopic and single-crystal X-ray analyses confirm the molecular assembly via -aggregation with a face-to-face orientation of the donor rings. The crystal structure analysis (, , , ) reveals that moderate π···π interactions (3.706 to 4.065 Å) between the donor rings cause the enhancement of the phosphorescence lifetime (26 to 245 ms), whereas the short phosphorescence lifetime (12 ms) of was observed because of the absence of π···π interactions. We found that shows a long lifetime (245 ms) as compared to other derivatives because of the presence of ethoxy (-OEt) groups that enables spin-orbit coupling caused by strong lone pair (O)···π interactions present in the molecule. Utilizing the PRTP feature of and the fluorescence emission of , we have shown data security applications in poly(methyl methacrylate).
具有持久室温磷光（PRTP）的有机室温磷光（RTP）材料在油墨、生物成像和光动力疗法方面引起了极大的关注。然而，增加有机分子寿命的设计原理仍不完善。在此，我们展示了供体（D）-受体（A）分子（、、、和），其在聚集体中的供体环具有相似的取向，从而导致大量的非共价相互作用。我们观察到、、和表现出PRTP，而在环境条件下仅表现出磷光发射（Φ = ∼11%），不具有PRTP特性。光谱和单晶X射线分析证实了通过供体环面对面取向的-聚集形成的分子组装。晶体结构分析（、、、）表明，供体环之间适度的π···π相互作用（3.706至4.065 Å）导致磷光寿命延长（26至245 ms），而由于不存在π···π相互作用，观察到的磷光寿命较短（12 ms）。我们发现，由于存在乙氧基（-OEt）基团，使得分子中存在的强孤对（O）···π相互作用引起自旋-轨道耦合，与其他衍生物相比，表现出较长的寿命（245 ms）。利用的PRTP特性和的荧光发射，我们展示了在聚甲基丙烯酸甲酯中的数据安全应用。
